Package javassist

Class CtClass

  • Direct Known Subclasses:
    CtPrimitiveType

    public abstract class CtClass
    extends java.lang.Object
    An instance of CtClass represents a class. It is obtained from ClassPool.
    See Also:
    ClassPool.get(String)
    • Field Summary

      Fields 
      Modifier and Type Field Description
      static CtClass booleanType
      The CtClass object representing the boolean type.
      static CtClass byteType
      The CtClass object representing the byte type.
      static CtClass charType
      The CtClass object representing the char type.
      static java.lang.String debugDump
      If the value of this field is not null, then all class files modified by Javassist are saved under the directory specified by this variable.
      static CtClass doubleType
      The CtClass object representing the double type.
      static CtClass floatType
      The CtClass object representing the float type.
      static CtClass intType
      The CtClass object representing the int type.
      static CtClass longType
      The CtClass object representing the long type.
      static CtClass shortType
      The CtClass object representing the short type.
      static java.lang.String version
      The version number of this release.
      static CtClass voidType
      The CtClass object representing the void type.
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods Deprecated Methods 
      Modifier and Type Method Description
      void addConstructor​(CtConstructor c)
      Adds a constructor.
      void addField​(CtField f)
      Adds a field.
      void addField​(CtField f, java.lang.String init)
      Adds a field with an initial value.
      void addField​(CtField f, CtField.Initializer init)
      Adds a field with an initial value.
      void addInterface​(CtClass anInterface)
      Adds an interface.
      void addMethod​(CtMethod m)
      Adds a method.
      void debugWriteFile()
      Writes a class file as writeFile() does although this method does not prune or freeze the class after writing the class file.
      void debugWriteFile​(java.lang.String directoryName)
      Writes a class file as writeFile() does although this method does not prune or freeze the class after writing the class file.
      void defrost()
      Defrosts the class so that the class can be modified again.
      void detach()
      Removes this CtClass object from the ClassPool.
      void freeze()
      Makes the class frozen.
      javassist.compiler.AccessorMaker getAccessorMaker()
      Undocumented method.
      java.lang.Object getAnnotation​(java.lang.Class<?> clz)
      Returns the annotation if the class has the specified annotation type.
      java.lang.Object[] getAnnotations()
      Returns the annotations associated with this class.
      byte[] getAttribute​(java.lang.String name)
      Obtains an attribute with the given name.
      java.lang.Object[] getAvailableAnnotations()
      Returns the annotations associated with this class.
      ClassFile getClassFile()
      Returns a class file for this class.
      ClassFile getClassFile2()
      Returns a class file for this class (read only).
      CtConstructor getClassInitializer()
      Gets the class initializer (static constructor) declared in the class.
      ClassPool getClassPool()
      Returns a ClassPool for this class.
      CtClass getComponentType()
      If this object represents an array, this method returns the component type of the array.
      CtConstructor getConstructor​(java.lang.String desc)
      Returns the constructor with the given signature, which is represented by a character string called method descriptor.
      CtConstructor[] getConstructors()
      Returns an array containing CtConstructor objects representing all the non-private constructors of the class.
      CtBehavior[] getDeclaredBehaviors()
      Gets all the constructors and methods declared in the class.
      CtClass[] getDeclaredClasses()
      Returns an array of nested classes declared in the class.
      CtConstructor getDeclaredConstructor​(CtClass[] params)
      Returns a constructor receiving the specified parameters.
      CtConstructor[] getDeclaredConstructors()
      Gets all the constructors declared in the class.
      CtField getDeclaredField​(java.lang.String name)
      Retrieves the field with the specified name among the fields declared in the class.
      CtField getDeclaredField​(java.lang.String name, java.lang.String desc)
      Retrieves the field with the specified name and type among the fields declared in the class.
      CtField[] getDeclaredFields()
      Gets all the fields declared in the class.
      CtMethod getDeclaredMethod​(java.lang.String name)
      Retrieves the method with the specified name among the methods declared in the class.
      CtMethod getDeclaredMethod​(java.lang.String name, CtClass[] params)
      Retrieves the method with the specified name and parameter types among the methods declared in the class.
      CtMethod[] getDeclaredMethods()
      Gets all methods declared in the class.
      CtMethod[] getDeclaredMethods​(java.lang.String name)
      Retrieves methods with the specified name among the methods declared in the class.
      CtClass getDeclaringClass()
      If this class is a member class or interface of another class, then the class enclosing this class is returned.
      CtBehavior getEnclosingBehavior()
      Returns the immediately enclosing method of this class.
      CtMethod getEnclosingMethod()
      Deprecated.
      The enclosing method might be a constructor.
      CtField getField​(java.lang.String name)
      Returns the field with the specified name.
      CtField getField​(java.lang.String name, java.lang.String desc)
      Returns the field with the specified name and type.
      CtField[] getFields()
      Returns an array containing CtField objects representing all the non-private fields of the class.
      java.lang.String getGenericSignature()
      Returns the generic signature of the class.
      CtClass[] getInterfaces()
      Obtains the class objects representing the interfaces implemented by the class or, if this object represents an interface, the interfaces extended by that interface.
      CtMethod getMethod​(java.lang.String name, java.lang.String desc)
      Returns the method with the given name and signature.
      CtMethod[] getMethods()
      Returns an array containing CtMethod objects representing all the non-private methods of the class.
      int getModifiers()
      Returns the modifiers for this class, encoded in an integer.
      java.lang.String getName()
      Obtains the fully-qualified name of the class.
      CtClass[] getNestedClasses()
      Returns an array of nested classes declared in the class.
      java.lang.String getPackageName()
      Obtains the package name.
      java.util.Collection<java.lang.String> getRefClasses()
      Returns a collection of the names of all the classes referenced in this class.
      java.lang.String getSimpleName()
      Obtains the not-qualified class name.
      CtClass getSuperclass()
      Obtains the class object representing the superclass of the class.
      java.net.URL getURL()
      Returns the uniform resource locator (URL) of the class file.
      boolean hasAnnotation​(java.lang.Class<?> annotationType)
      Returns true if the class has the specified annotation type.
      boolean hasAnnotation​(java.lang.String annotationTypeName)
      Returns true if the class has the specified annotation type.
      void instrument​(CodeConverter converter)
      Applies the given converter to all methods and constructors declared in the class.
      void instrument​(ExprEditor editor)
      Modifies the bodies of all methods and constructors declared in the class.
      boolean isAnnotation()
      Determines whether this object represents an annotation type.
      boolean isArray()
      Returns true if this object represents an array type.
      boolean isEnum()
      Determines whether this object represents an enum.
      boolean isFrozen()
      Returns true if the class has been loaded or written out and thus it cannot be modified any more.
      boolean isInterface()
      Determines whether this object represents a class or an interface.
      boolean isModified()
      Returns true if the definition of the class has been modified.
      boolean isPrimitive()
      Returns true if this object represents a primitive Java type: boolean, byte, char, short, int, long, float, double, or void.
      static void main​(java.lang.String[] args)
      Prints the version number and the copyright notice.
      CtConstructor makeClassInitializer()
      Makes an empty class initializer (static constructor).
      CtClass makeNestedClass​(java.lang.String name, boolean isStatic)
      Makes a new public nested class.
      java.lang.String makeUniqueName​(java.lang.String prefix)
      Makes a unique member name.
      void prune()
      Discards unnecessary attributes, in particular, CodeAttributes (method bodies) of the class, to minimize the memory footprint.
      void rebuildClassFile()
      If this method is called, the class file will be rebuilt when it is finally generated by toBytecode() and writeFile().
      void removeConstructor​(CtConstructor c)
      Removes a constructor declared in this class.
      void removeField​(CtField f)
      Removes a field declared in this class.
      void removeMethod​(CtMethod m)
      Removes a method declared in this class.
      void replaceClassName​(java.lang.String oldName, java.lang.String newName)
      Substitutes newName for all occurrences of a class name oldName in the class file.
      void replaceClassName​(ClassMap map)
      Changes class names appearing in the class file according to the given map.
      void setAttribute​(java.lang.String name, byte[] data)
      Adds a named attribute.
      void setGenericSignature​(java.lang.String sig)
      Sets the generic signature of the class.
      void setInterfaces​(CtClass[] list)
      Sets implemented interfaces.
      void setModifiers​(int mod)
      Sets the modifiers.
      void setName​(java.lang.String name)
      Sets the class name
      void setSuperclass​(CtClass clazz)
      Changes a super class unless this object represents an interface.
      boolean stopPruning​(boolean stop)
      Disallows (or allows) automatically pruning this CtClass object.
      boolean subclassOf​(CtClass superclass)
      Determines whether the class directly or indirectly extends the given class.
      boolean subtypeOf​(CtClass clazz)
      Returns true if this class extends or implements clazz.
      byte[] toBytecode()
      Converts this class to a class file.
      void toBytecode​(java.io.DataOutputStream out)
      Converts this class to a class file.
      java.lang.Class<?> toClass()
      Converts this class to a java.lang.Class object.
      java.lang.Class<?> toClass​(java.lang.Class<?> neighbor)
      Converts this class to a java.lang.Class object.
      java.lang.Class<?> toClass​(java.lang.ClassLoader loader)
      Deprecated.
      java.lang.Class<?> toClass​(java.lang.ClassLoader loader, java.security.ProtectionDomain domain)
      Converts this class to a java.lang.Class object.
      java.lang.Class<?> toClass​(java.lang.invoke.MethodHandles.Lookup lookup)
      Converts this class to a java.lang.Class object.
      java.lang.String toString()
      Converts the object to a string.
      void writeFile()
      Writes a class file represented by this CtClass object in the current directory.
      void writeFile​(java.lang.String directoryName)
      Writes a class file represented by this CtClass object on a local disk.
      • Methods inherited from class java.lang.Object

        equals, getClass, hashCode, notify, notifyAll, wait, wait, wait
    • Field Detail

      • debugDump

        public static java.lang.String debugDump
        If the value of this field is not null, then all class files modified by Javassist are saved under the directory specified by this variable. For example, if the value is "./debug", then all class files are saved there. The directory name must not end with a directory separator such as /.

        The default value is null.

        Since:
        3.16
        See Also:
        debugWriteFile(String)
      • version

        public static final java.lang.String version
        The version number of this release.
        See Also:
        Constant Field Values
      • booleanType

        public static CtClass booleanType
        The CtClass object representing the boolean type.
      • charType

        public static CtClass charType
        The CtClass object representing the char type.
      • byteType

        public static CtClass byteType
        The CtClass object representing the byte type.
      • shortType

        public static CtClass shortType
        The CtClass object representing the short type.
      • intType

        public static CtClass intType
        The CtClass object representing the int type.
      • longType

        public static CtClass longType
        The CtClass object representing the long type.
      • floatType

        public static CtClass floatType
        The CtClass object representing the float type.
      • doubleType

        public static CtClass doubleType
        The CtClass object representing the double type.
      • voidType

        public static CtClass voidType
        The CtClass object representing the void type.
    • Method Detail

      • main

        public static void main​(java.lang.String[] args)
        Prints the version number and the copyright notice.

        The following command invokes this method:

        java -jar javassist.jar
      • toString

        public java.lang.String toString()
        Converts the object to a string.
        Overrides:
        toString in class java.lang.Object
      • getClassPool

        public ClassPool getClassPool()
        Returns a ClassPool for this class.
      • getClassFile

        public ClassFile getClassFile()
        Returns a class file for this class.

        This method is not available if isFrozen() is true.

      • getClassFile2

        public ClassFile getClassFile2()
        Returns a class file for this class (read only). Normal applications do not need calling this method. Use getClassFile().

        The ClassFile object obtained by this method is read only. Changes to this object might not be reflected on a class file generated by toBytecode(), toClass(), etc.

        This method is available even if isFrozen() is true. However, if the class is frozen, it might be also pruned.

        See Also:
        getClassFile(), isFrozen(), prune()
      • getAccessorMaker

        public javassist.compiler.AccessorMaker getAccessorMaker()
        Undocumented method. Do not use; internal-use only.
      • isModified

        public boolean isModified()
        Returns true if the definition of the class has been modified.
      • isFrozen

        public boolean isFrozen()
        Returns true if the class has been loaded or written out and thus it cannot be modified any more.
        See Also:
        defrost(), detach()
      • freeze

        public void freeze()
        Makes the class frozen.
        Since:
        3.6
        See Also:
        isFrozen(), defrost()
      • defrost

        public void defrost()
        Defrosts the class so that the class can be modified again.

        To avoid changes that will be never reflected, the class is frozen to be unmodifiable if it is loaded or written out. This method should be called only in a case that the class will be reloaded or written out later again.

        If defrost() will be called later, pruning must be disallowed in advance.

        See Also:
        isFrozen(), stopPruning(boolean), detach()
      • isPrimitive

        public boolean isPrimitive()
        Returns true if this object represents a primitive Java type: boolean, byte, char, short, int, long, float, double, or void.
      • isArray

        public boolean isArray()
        Returns true if this object represents an array type.
      • getComponentType

        public CtClass getComponentType()
                                 throws NotFoundException
        If this object represents an array, this method returns the component type of the array. Otherwise, it returns null.
        Throws:
        NotFoundException
      • subtypeOf

        public boolean subtypeOf​(CtClass clazz)
                          throws NotFoundException
        Returns true if this class extends or implements clazz. It also returns true if this class is the same as clazz.
        Throws:
        NotFoundException
      • getName

        public java.lang.String getName()
        Obtains the fully-qualified name of the class.
      • getSimpleName

        public final java.lang.String getSimpleName()
        Obtains the not-qualified class name.
      • getPackageName

        public final java.lang.String getPackageName()
        Obtains the package name. It may be null.
      • setName

        public void setName​(java.lang.String name)
        Sets the class name
        Parameters:
        name - fully-qualified name
      • getGenericSignature

        public java.lang.String getGenericSignature()
        Returns the generic signature of the class.

        The generics of Java is implemented by the erasure technique. After compilation, all type parameters are dropped off from the main part of a class file. However, for reflection, the type parameters are encoded into generic signatures and attached to a class file.

        Returns:
        null if the generic signature is not included.
        Since:
        3.17
        See Also:
        SignatureAttribute.toClassSignature(String), CtMember.getGenericSignature()
      • setGenericSignature

        public void setGenericSignature​(java.lang.String sig)
        Sets the generic signature of the class.

        The generics of Java is implemented by the erasure technique. After compilation, all type parameters are dropped off from the main part of a class file. However, for reflection, the type parameters must be encoded into generic signatures and attached to a class file.

        For example,

        class List<T> {
             T value;
             T get() { return value; }
             void set(T v) { value = v; }
         }
         

        this class is generated by the following code:

         ClassPool pool = ClassPool.getDefault();
         CtClass cc = pool.makeClass("List");
         CtClass objectClass = pool.get(CtClass.javaLangObject);
         ClassSignature cs = new ClassSignature(
                                 new TypeParameter[] { new TypeParameter("T") });
         cc.setGenericSignature(cs.encode());    // <T:Ljava/lang/Object;>Ljava/lang/Object;
        
         CtField f = new CtField(objClass, "value", cc);
         TypeVariable tvar = new TypeVariable("T");
         f.setGenericSignature(tvar.encode());   // TT;
         cc.addField(f);
        
         CtMethod m = CtNewMethod.make("public Object get(){return value;}", cc);
         MethodSignature ms = new MethodSignature(null, null, tvar, null);
         m.setGenericSignature(ms.encode());     // ()TT;
         cc.addMethod(m);
        
         CtMethod m2 = CtNewMethod.make("public void set(Object v){value = v;}", cc);
         MethodSignature ms2 = new MethodSignature(null, new Type[] { tvar },
                                                   new BaseType("void"), null);
         m2.setGenericSignature(ms2.encode());   // (TT;)V;
         cc.addMethod(m2);
        
         cc.writeFile();
         

        The generated class file is equivalent to the following:

        class List {
             Object value;
             Object get() { return value; }
             void set(Object v) { value = v; }
         }

        but it includes generic signatures for the class, the field, and the methods so that the type variable T can be accessible through reflection.

        MethodSignature is a utility class. You can directly pass the signature string to the setGenericSignature method. For the specification of the signatures, see Section 4.7.9.1 Signatures of The Java Virtual Machine Specification (Java SE 8).

        Parameters:
        sig - a generic signature.
        Since:
        3.17
        See Also:
        SignatureAttribute.ClassSignature.encode(), SignatureAttribute.MethodSignature.encode(), CtMember.setGenericSignature(String)
      • replaceClassName

        public void replaceClassName​(java.lang.String oldName,
                                     java.lang.String newName)
        Substitutes newName for all occurrences of a class name oldName in the class file.
        Parameters:
        oldName - replaced class name
        newName - substituted class name
      • replaceClassName

        public void replaceClassName​(ClassMap map)
        Changes class names appearing in the class file according to the given map.

        All the class names appearing in the class file are tested with map to determine whether each class name is replaced or not. Thus this method can be used for collecting all the class names in the class file. To do that, first define a subclass of ClassMap so that get() records all the given parameters. Then, make an instance of that subclass as an empty hash-table. Finally, pass that instance to this method. After this method finishes, that instance would contain all the class names appearing in the class file.

        Parameters:
        map - the hashtable associating replaced class names with substituted names.
      • getRefClasses

        public java.util.Collection<java.lang.String> getRefClasses()
        Returns a collection of the names of all the classes referenced in this class. That collection includes the name of this class.

        This method may return null.

        Returns:
        a Collection<String> object.
      • isInterface

        public boolean isInterface()
        Determines whether this object represents a class or an interface. It returns true if this object represents an interface.
      • isAnnotation

        public boolean isAnnotation()
        Determines whether this object represents an annotation type. It returns true if this object represents an annotation type.
        Since:
        3.2
      • isEnum

        public boolean isEnum()
        Determines whether this object represents an enum. It returns true if this object represents an enum.
        Since:
        3.2
      • getModifiers

        public int getModifiers()
        Returns the modifiers for this class, encoded in an integer. For decoding, use javassist.Modifier.

        If the class is a static nested class (a.k.a. static inner class), the returned modifiers include Modifier.STATIC.

        See Also:
        Modifier
      • hasAnnotation

        public boolean hasAnnotation​(java.lang.Class<?> annotationType)
        Returns true if the class has the specified annotation type.
        Parameters:
        annotationType - the annotation type.
        Returns:
        true if the annotation is found, otherwise false.
        Since:
        3.11
      • hasAnnotation

        public boolean hasAnnotation​(java.lang.String annotationTypeName)
        Returns true if the class has the specified annotation type.
        Parameters:
        annotationTypeName - the name of annotation type.
        Returns:
        true if the annotation is found, otherwise false.
        Since:
        3.21
      • getAnnotation

        public java.lang.Object getAnnotation​(java.lang.Class<?> clz)
                                       throws java.lang.ClassNotFoundException
        Returns the annotation if the class has the specified annotation type. For example, if an annotation @Author is associated with this class, an Author object is returned. The member values can be obtained by calling methods on the Author object.
        Parameters:
        clz - the annotation type.
        Returns:
        the annotation if found, otherwise null.
        Throws:
        java.lang.ClassNotFoundException
        Since:
        3.11
      • getAnnotations

        public java.lang.Object[] getAnnotations()
                                          throws java.lang.ClassNotFoundException
        Returns the annotations associated with this class. For example, if an annotation @Author is associated with this class, the returned array contains an Author object. The member values can be obtained by calling methods on the Author object.
        Returns:
        an array of annotation-type objects.
        Throws:
        java.lang.ClassNotFoundException
        Since:
        3.1
        See Also:
        CtMember.getAnnotations()
      • getAvailableAnnotations

        public java.lang.Object[] getAvailableAnnotations()
        Returns the annotations associated with this class. This method is equivalent to getAnnotations() except that, if any annotations are not on the classpath, they are not included in the returned array.
        Returns:
        an array of annotation-type objects.
        Since:
        3.3
        See Also:
        getAnnotations(), CtMember.getAvailableAnnotations()
      • getDeclaredClasses

        public CtClass[] getDeclaredClasses()
                                     throws NotFoundException
        Returns an array of nested classes declared in the class. Nested classes are inner classes, anonymous classes, local classes, and static nested classes. This simply calls getNestedClasses().
        Throws:
        NotFoundException
        Since:
        3.15
        See Also:
        getNestedClasses()
      • getNestedClasses

        public CtClass[] getNestedClasses()
                                   throws NotFoundException
        Returns an array of nested classes declared in the class. Nested classes are inner classes, anonymous classes, local classes, and static nested classes.
        Throws:
        NotFoundException
        Since:
        3.2
      • setModifiers

        public void setModifiers​(int mod)
        Sets the modifiers.

        If the class is a nested class, this method also modifies the class declaring that nested class (i.e. the enclosing class is modified).

        Parameters:
        mod - modifiers encoded by javassist.Modifier
        See Also:
        Modifier
      • subclassOf

        public boolean subclassOf​(CtClass superclass)
        Determines whether the class directly or indirectly extends the given class. If this class extends a class A and the class A extends a class B, then subclassof(B) returns true.

        This method returns true if the given class is identical to the class represented by this object.

      • getSuperclass

        public CtClass getSuperclass()
                              throws NotFoundException
        Obtains the class object representing the superclass of the class. It returns null if this object represents the java.lang.Object class and thus it does not have the super class.

        If this object represents an interface, this method always returns the java.lang.Object class. To obtain the super interfaces extended by that interface, call getInterfaces().

        Throws:
        NotFoundException
      • setSuperclass

        public void setSuperclass​(CtClass clazz)
                           throws CannotCompileException
        Changes a super class unless this object represents an interface. The new super class must be compatible with the old one; for example, it should inherit from the old super class.

        If this object represents an interface, this method is equivalent to addInterface(); it appends clazz to the list of the super interfaces extended by that interface. Note that an interface can extend multiple super interfaces.

        Throws:
        CannotCompileException
        See Also:
        replaceClassName(String, String), replaceClassName(ClassMap)
      • getInterfaces

        public CtClass[] getInterfaces()
                                throws NotFoundException
        Obtains the class objects representing the interfaces implemented by the class or, if this object represents an interface, the interfaces extended by that interface.
        Throws:
        NotFoundException
      • setInterfaces

        public void setInterfaces​(CtClass[] list)
        Sets implemented interfaces. If this object represents an interface, this method sets the interfaces extended by that interface.
        Parameters:
        list - a list of the CtClass objects representing interfaces, or null if the class implements no interfaces.
      • addInterface

        public void addInterface​(CtClass anInterface)
        Adds an interface.
        Parameters:
        anInterface - the added interface.
      • getDeclaringClass

        public CtClass getDeclaringClass()
                                  throws NotFoundException
        If this class is a member class or interface of another class, then the class enclosing this class is returned.
        Returns:
        null if this class is a top-level class or an anonymous class.
        Throws:
        NotFoundException
      • getEnclosingBehavior

        public CtBehavior getEnclosingBehavior()
                                        throws NotFoundException
        Returns the immediately enclosing method of this class. It might be not a method but a constructor. This method works only with JDK 1.5 or later.
        Returns:
        null if this class is not a local class or an anonymous class.
        Throws:
        NotFoundException
      • makeNestedClass

        public CtClass makeNestedClass​(java.lang.String name,
                                       boolean isStatic)
        Makes a new public nested class. If this method is called, the CtClass, which encloses the nested class, is modified since a class file includes a list of nested classes.

        The current implementation only supports a static nested class. isStatic must be true.

        Parameters:
        name - the simple name of the nested class.
        isStatic - true if the nested class is static.
      • getFields

        public CtField[] getFields()
        Returns an array containing CtField objects representing all the non-private fields of the class. That array includes non-private fields inherited from the superclasses.
      • getField

        public CtField getField​(java.lang.String name)
                         throws NotFoundException
        Returns the field with the specified name. The returned field may be a private field declared in a super class or interface.
        Throws:
        NotFoundException
      • getField

        public CtField getField​(java.lang.String name,
                                java.lang.String desc)
                         throws NotFoundException
        Returns the field with the specified name and type. The returned field may be a private field declared in a super class or interface. Unlike Java, the JVM allows a class to have multiple fields with the same name but different types.
        Parameters:
        name - the field name.
        desc - the type descriptor of the field. It is available by CtField.getSignature().
        Throws:
        NotFoundException
        See Also:
        CtField.getSignature()
      • getDeclaredFields

        public CtField[] getDeclaredFields()
        Gets all the fields declared in the class. The inherited fields are not included.

        Note: the result does not include inherited fields.

      • getDeclaredField

        public CtField getDeclaredField​(java.lang.String name)
                                 throws NotFoundException
        Retrieves the field with the specified name among the fields declared in the class.

        Note: this method does not search the super classes.

        Throws:
        NotFoundException
      • getDeclaredField

        public CtField getDeclaredField​(java.lang.String name,
                                        java.lang.String desc)
                                 throws NotFoundException
        Retrieves the field with the specified name and type among the fields declared in the class. Unlike Java, the JVM allows a class to have multiple fields with the same name but different types.

        Note: this method does not search the super classes.

        Parameters:
        name - the field name.
        desc - the type descriptor of the field. It is available by CtField.getSignature().
        Throws:
        NotFoundException
        See Also:
        CtField.getSignature()
      • getDeclaredBehaviors

        public CtBehavior[] getDeclaredBehaviors()
        Gets all the constructors and methods declared in the class.
      • getConstructors

        public CtConstructor[] getConstructors()
        Returns an array containing CtConstructor objects representing all the non-private constructors of the class.
      • getConstructor

        public CtConstructor getConstructor​(java.lang.String desc)
                                     throws NotFoundException
        Returns the constructor with the given signature, which is represented by a character string called method descriptor. For details of the method descriptor, see the JVM specification or javassist.bytecode.Descriptor.
        Parameters:
        desc - method descriptor
        Throws:
        NotFoundException
        See Also:
        Descriptor
      • getDeclaredConstructors

        public CtConstructor[] getDeclaredConstructors()
        Gets all the constructors declared in the class.
        See Also:
        CtConstructor
      • getClassInitializer

        public CtConstructor getClassInitializer()
        Gets the class initializer (static constructor) declared in the class. This method returns null if no class initializer is not declared.
        See Also:
        makeClassInitializer(), CtConstructor
      • getMethods

        public CtMethod[] getMethods()
        Returns an array containing CtMethod objects representing all the non-private methods of the class. That array includes non-private methods inherited from the superclasses.
      • getMethod

        public CtMethod getMethod​(java.lang.String name,
                                  java.lang.String desc)
                           throws NotFoundException
        Returns the method with the given name and signature. The returned method may be declared in a super class. The method signature is represented by a character string called method descriptor, which is defined in the JVM specification.
        Parameters:
        name - method name
        desc - method descriptor
        Throws:
        NotFoundException
        See Also:
        CtBehavior.getSignature(), Descriptor
      • getDeclaredMethods

        public CtMethod[] getDeclaredMethods()
        Gets all methods declared in the class. The inherited methods are not included.
        See Also:
        CtMethod
      • getDeclaredMethod

        public CtMethod getDeclaredMethod​(java.lang.String name,
                                          CtClass[] params)
                                   throws NotFoundException
        Retrieves the method with the specified name and parameter types among the methods declared in the class.

        Note: this method does not search the superclasses.

        Parameters:
        name - method name
        params - parameter types
        Throws:
        NotFoundException
        See Also:
        CtMethod
      • getDeclaredMethods

        public CtMethod[] getDeclaredMethods​(java.lang.String name)
                                      throws NotFoundException
        Retrieves methods with the specified name among the methods declared in the class. Multiple methods with different parameters may be returned.

        Note: this method does not search the superclasses.

        Parameters:
        name - method name.
        Throws:
        NotFoundException
        Since:
        3.19
      • getDeclaredMethod

        public CtMethod getDeclaredMethod​(java.lang.String name)
                                   throws NotFoundException
        Retrieves the method with the specified name among the methods declared in the class. If there are multiple methods with the specified name, then this method returns one of them.

        Note: this method does not search the superclasses.

        Throws:
        NotFoundException
        See Also:
        CtMethod
      • removeConstructor

        public void removeConstructor​(CtConstructor c)
                               throws NotFoundException
        Removes a constructor declared in this class.
        Parameters:
        c - removed constructor.
        Throws:
        NotFoundException - if the constructor is not found.
      • removeMethod

        public void removeMethod​(CtMethod m)
                          throws NotFoundException
        Removes a method declared in this class.
        Parameters:
        m - removed method.
        Throws:
        NotFoundException - if the method is not found.
      • addField

        public void addField​(CtField f,
                             java.lang.String init)
                      throws CannotCompileException
        Adds a field with an initial value.

        The CtField belonging to another CtClass cannot be directly added to this class. Only a field created for this class can be added.

        The initial value is given as an expression written in Java. Any regular Java expression can be used for specifying the initial value. The followings are examples.

         cc.addField(f, "0")               // the initial value is 0.
         cc.addField(f, "i + 1")           // i + 1.
         cc.addField(f, "new Point()");    // a Point object.
         

        Here, the type of variable cc is CtClass. The type of f is CtField.

        Note: do not change the modifier of the field (in particular, do not add or remove static to/from the modifier) after it is added to the class by addField().

        Parameters:
        init - an expression for the initial value.
        Throws:
        CannotCompileException
        See Also:
        CtField.Initializer.byExpr(String), CtField(CtField,CtClass)
      • addField

        public void addField​(CtField f,
                             CtField.Initializer init)
                      throws CannotCompileException
        Adds a field with an initial value.

        The CtField belonging to another CtClass cannot be directly added to this class. Only a field created for this class can be added.

        For example,

         CtClass cc = ...;
         addField(new CtField(CtClass.intType, "i", cc),
                  CtField.Initializer.constant(1));
         

        This code adds an int field named "i". The initial value of this field is 1.

        Parameters:
        init - specifies the initial value of the field.
        Throws:
        CannotCompileException
        See Also:
        CtField(CtField,CtClass)
      • removeField

        public void removeField​(CtField f)
                         throws NotFoundException
        Removes a field declared in this class.
        Parameters:
        f - removed field.
        Throws:
        NotFoundException - if the field is not found.
      • getAttribute

        public byte[] getAttribute​(java.lang.String name)
        Obtains an attribute with the given name. If that attribute is not found in the class file, this method returns null.

        This is a convenient method mainly for obtaining a user-defined attribute. For dealing with attributes, see the javassist.bytecode package. For example, the following expression returns all the attributes of a class file.

         getClassFile().getAttributes()
         
        Parameters:
        name - attribute name
        See Also:
        AttributeInfo
      • setAttribute

        public void setAttribute​(java.lang.String name,
                                 byte[] data)
        Adds a named attribute. An arbitrary data (smaller than 64Kb) can be saved in the class file. Some attribute name are reserved by the JVM. The attributes with the non-reserved names are ignored when a class file is loaded into the JVM. If there is already an attribute with the same name, this method substitutes the new one for it.

        This is a convenient method mainly for adding a user-defined attribute. For dealing with attributes, see the javassist.bytecode package. For example, the following expression adds an attribute info to a class file.

         getClassFile().addAttribute(info)
         
        Parameters:
        name - attribute name
        data - attribute value
        See Also:
        AttributeInfo
      • instrument

        public void instrument​(CodeConverter converter)
                        throws CannotCompileException
        Applies the given converter to all methods and constructors declared in the class. This method calls instrument() on every CtMethod and CtConstructor object in the class.
        Parameters:
        converter - specifies how to modify.
        Throws:
        CannotCompileException
      • instrument

        public void instrument​(ExprEditor editor)
                        throws CannotCompileException
        Modifies the bodies of all methods and constructors declared in the class. This method calls instrument() on every CtMethod and CtConstructor object in the class.
        Parameters:
        editor - specifies how to modify.
        Throws:
        CannotCompileException
      • toClass

        public java.lang.Class<?> toClass()
                                   throws CannotCompileException
        Converts this class to a java.lang.Class object. Once this method is called, further modifications are not allowed any more. To load the class, this method uses the context class loader of the current thread. If the program is running on some application server, the context class loader might be inappropriate to load the class.

        Warning: In Java 11 or later, the call to this method will print a warning message:

         WARNING: An illegal reflective access operation has occurred
         WARNING: Illegal reflective access by javassist.util.proxy.SecurityActions$3 ...
         WARNING: Please consider reporting this to the maintainers of javassist.util.proxy.SecurityActions$3
         WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
         WARNING: All illegal access operations will be denied in a future release
         

        To avoid this message, use toClass(Class) or toClass(java.lang.invoke.MethodHandles.Lookup). toClass() will be unavailable in a future release.

        Warning: A Class object returned by this method may not work with a security manager or a signed jar file because a protection domain is not specified.

        Note: this method calls toClass() in ClassPool.

        Throws:
        CannotCompileException
        See Also:
        toClass(java.lang.invoke.MethodHandles.Lookup), toClass(Class), ClassPool.toClass(CtClass)
      • toClass

        public java.lang.Class<?> toClass​(java.lang.Class<?> neighbor)
                                   throws CannotCompileException
        Converts this class to a java.lang.Class object. Once this method is called, further modifications are not allowed any more.

        This method is provided for convenience. You should use toClass(Lookup) for better compatibility with the module system.

        Note: this method calls toClass() in ClassPool.

        Warning: A Class object returned by this method may not work with a security manager or a signed jar file because a protection domain is not specified.

        Parameters:
        neighbor - A class belonging to the same package that this class belongs to. It is used to load the class.
        Throws:
        CannotCompileException
        Since:
        3.24
        See Also:
        ClassPool.toClass(CtClass,Class), toClass(java.lang.invoke.MethodHandles.Lookup)
      • toClass

        public java.lang.Class<?> toClass​(java.lang.invoke.MethodHandles.Lookup lookup)
                                   throws CannotCompileException
        Converts this class to a java.lang.Class object. Once this method is called, further modifications are not allowed any more.

        This method is provided for convenience. If you need more complex functionality, you should write your own class loader.

        Note: this method calls toClass() in ClassPool.

        Warning: A Class object returned by this method may not work with a security manager or a signed jar file because a protection domain is not specified.

        Parameters:
        lookup - used when loading the class. It has to have an access right to define a new class.
        Throws:
        CannotCompileException
        Since:
        3.24
        See Also:
        ClassPool.toClass(CtClass,java.lang.invoke.MethodHandles.Lookup)
      • toClass

        public java.lang.Class<?> toClass​(java.lang.ClassLoader loader,
                                          java.security.ProtectionDomain domain)
                                   throws CannotCompileException
        Converts this class to a java.lang.Class object. Once this method is called, further modifications are not allowed any more.

        The class file represented by this CtClass is loaded by the given class loader to construct a java.lang.Class object. Since a private method on the class loader is invoked through the reflection API, the caller must have permissions to do that.

        An easy way to obtain ProtectionDomain object is to call getProtectionDomain() in java.lang.Class. It returns the domain that the class belongs to.

        This method is provided for convenience. If you need more complex functionality, you should write your own class loader.

        Note: this method calls toClass() in ClassPool.

        Parameters:
        loader - the class loader used to load this class. If it is null, the class loader returned by ClassPool.getClassLoader() is used.
        domain - the protection domain that the class belongs to. If it is null, the default domain created by java.lang.ClassLoader is used.
        Throws:
        CannotCompileException
        Since:
        3.3
        See Also:
        ClassPool.toClass(CtClass,java.lang.ClassLoader)
      • toClass

        @Deprecated
        public final java.lang.Class<?> toClass​(java.lang.ClassLoader loader)
                                         throws CannotCompileException
        Deprecated.
        Converts this class to a java.lang.Class object.

        Warning: A Class object returned by this method may not work with a security manager or a signed jar file because a protection domain is not specified.

        Throws:
        CannotCompileException
      • detach

        public void detach()
        Removes this CtClass object from the ClassPool. After this method is called, any method cannot be called on the removed CtClass object.

        If get() in ClassPool is called with the name of the removed method, the ClassPool will read the class file again and constructs another CtClass object representing the same class.

      • stopPruning

        public boolean stopPruning​(boolean stop)
        Disallows (or allows) automatically pruning this CtClass object.

        Javassist can automatically prune a CtClass object when toBytecode() (or toClass(), writeFile()) is called. Since a ClassPool holds all instances of CtClass even after toBytecode() (or toClass(), writeFile()) is called, pruning may significantly save memory consumption.

        If ClassPool.doPruning is true, the automatic pruning is on by default. Otherwise, it is off. The default value of ClassPool.doPruning is false.

        Parameters:
        stop - disallow pruning if true. Otherwise, allow.
        Returns:
        the previous status of pruning. true if pruning is already stopped.
        See Also:
        detach(), prune(), ClassPool.doPruning
      • prune

        public void prune()
        Discards unnecessary attributes, in particular, CodeAttributes (method bodies) of the class, to minimize the memory footprint. After calling this method, the class is read only. It cannot be modified any more. Furthermore, toBytecode(), writeFile(), toClass(), or instrument() cannot be called. However, the method names and signatures in the class etc. are still accessible.

        toBytecode(), writeFile(), and toClass() internally call this method if automatic pruning is on.

        According to some experiments, pruning does not really reduce memory consumption. Only about 20%. Since pruning takes time, it might not pay off. So the automatic pruning is off by default.

        See Also:
        stopPruning(boolean), detach(), ClassPool.doPruning, toBytecode(), toClass(Class), writeFile(), instrument(CodeConverter), instrument(ExprEditor)
      • rebuildClassFile

        public void rebuildClassFile()
        If this method is called, the class file will be rebuilt when it is finally generated by toBytecode() and writeFile(). For a performance reason, the symbol table of the class file may contain unused entries, for example, after a method or a filed is deleted. This method removes those unused entries. This removal will minimize the size of the class file.
        Since:
        3.8.1
      • toBytecode

        public byte[] toBytecode()
                          throws java.io.IOException,
                                 CannotCompileException
        Converts this class to a class file. Once this method is called, further modifications are not possible any more.
        Returns:
        the contents of the class file.
        Throws:
        java.io.IOException
        CannotCompileException
      • writeFile

        public void writeFile​(java.lang.String directoryName)
                       throws CannotCompileException,
                              java.io.IOException
        Writes a class file represented by this CtClass object on a local disk. Once this method is called, further modifications are not possible any more.
        Parameters:
        directoryName - it must end without a directory separator.
        Throws:
        CannotCompileException
        java.io.IOException
        See Also:
        debugWriteFile(String)
      • debugWriteFile

        public void debugWriteFile()
        Writes a class file as writeFile() does although this method does not prune or freeze the class after writing the class file. Note that, once writeFile() or toBytecode() is called, it cannot be called again since the class is pruned and frozen. This method would be useful for debugging.
      • debugWriteFile

        public void debugWriteFile​(java.lang.String directoryName)
        Writes a class file as writeFile() does although this method does not prune or freeze the class after writing the class file. Note that, once writeFile() or toBytecode() is called, it cannot be called again since the class is pruned and frozen. This method would be useful for debugging.
        Parameters:
        directoryName - it must end without a directory separator.
      • toBytecode

        public void toBytecode​(java.io.DataOutputStream out)
                        throws CannotCompileException,
                               java.io.IOException
        Converts this class to a class file. Once this method is called, further modifications are not possible any more.

        This method dose not close the output stream in the end.

        Parameters:
        out - the output stream that a class file is written to.
        Throws:
        CannotCompileException
        java.io.IOException
      • makeUniqueName

        public java.lang.String makeUniqueName​(java.lang.String prefix)
        Makes a unique member name. This method guarantees that the returned name is not used as a prefix of any methods or fields visible in this class. If the returned name is XYZ, then any method or field names in this class do not start with XYZ.
        Parameters:
        prefix - the prefix of the member name.