Package javassist

Class CtClass

java.lang.Object
javassist.CtClass
Direct Known Subclasses:
CtPrimitiveType
public abstract class CtClass extends Object
An instance of CtClass represents a class. It is obtained from ClassPool.
See Also:

  • Field Details

    • debugDump

      public static 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:

    • version

      public static final String version
      The version number of this release.
      See Also:

    • 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 Details

    • main

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

      The following command invokes this method: 

      java -jar javassist.jar

    • toString

      public String toString()
      Converts the object to a string.
      Overrides:
      toString in class 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:

    • getAccessorMaker

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

    • getURL

      public URL getURL() throws NotFoundException
      Returns the uniform resource locator (URL) of the class file.
      Throws:
      NotFoundException

    • 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:

    • freeze

      public void freeze()
      Makes the class frozen.
      Since:
      3.6
      See Also:

    • 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:

    • 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.

    • isKotlin

      public boolean isKotlin()
      Returns true if this object represents a Kotlin class.
      Since:
      3.26

    • 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 String getName()
      Obtains the fully-qualified name of the class.

    • getSimpleName

      public final String getSimpleName()
      Obtains the not-qualified class name.

    • getPackageName

      public final String getPackageName()
      Obtains the package name. It may be null.

    • setName

      public void setName(String name)
      Sets the class name
      Parameters:
      name - fully-qualified name

    • getGenericSignature

      public 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:

    • setGenericSignature

      public void setGenericSignature(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:

    • replaceClassName

      public void replaceClassName(String oldName, 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 Collection<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:

    • hasAnnotation

      public boolean hasAnnotation(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(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 Object getAnnotation(Class<?> clz) throws 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:
      ClassNotFoundException
      Since:
      3.11

    • getAnnotations

      public Object[] getAnnotations() throws 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:
      ClassNotFoundException
      Since:
      3.1
      See Also:

    • getAvailableAnnotations

      public 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:

    • 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

      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:

    • 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:

    • 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

    • getEnclosingMethod

      @Deprecated public final CtMethod getEnclosingMethod() throws NotFoundException
      Deprecated.
      The enclosing method might be a constructor. Use getEnclosingBehavior().
      Returns the immediately enclosing method of this class. 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
      See Also:

    • 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(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(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(String name, 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:

    • 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(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(String name, 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:

    • 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(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:

    • getDeclaredConstructors

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

    • getDeclaredConstructor

      public CtConstructor getDeclaredConstructor(CtClass[] params) throws NotFoundException
      Returns a constructor receiving the specified parameters.
      Parameters:
      params - parameter types.
      Throws:
      NotFoundException

    • 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:

    • 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(String name, 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:

    • getDeclaredMethods

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

    • getDeclaredMethod

      public CtMethod getDeclaredMethod(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:

    • getDeclaredMethods

      public CtMethod[] getDeclaredMethods(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(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:

    • makeClassInitializer

      public CtConstructor makeClassInitializer() throws CannotCompileException
      Makes an empty class initializer (static constructor). If the class already includes a class initializer, this method returns it.
      Throws:
      CannotCompileException
      See Also:

    • addConstructor

      public void addConstructor(CtConstructor c) throws CannotCompileException
      Adds a constructor. To add a class initializer (static constructor), call makeClassInitializer().
      Throws:
      CannotCompileException
      See Also:

    • 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.

    • addMethod

      public void addMethod(CtMethod m) throws CannotCompileException
      Adds a method.
      Throws:
      CannotCompileException

    • 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) throws CannotCompileException
      Adds a field.

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

      Throws:
      CannotCompileException
      See Also:

    • addField

      public void addField(CtField f, 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:

    • 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:

    • 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(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:

    • setAttribute

      public void setAttribute(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:

    • 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 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

      public Class<?> toClass(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:

    • toClass

      public Class<?> toClass(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:

    • toClass

      public Class<?> toClass(ClassLoader loader, 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:

    • toClass

      @Deprecated public final Class<?> toClass(ClassLoader loader) throws CannotCompileException
      Deprecated.
      Replaced by toClass(ClassLoader,ProtectionDomain)
      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:

    • 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:

    • 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 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:
      IOException
      CannotCompileException

    • writeFile

      public void writeFile() throws NotFoundException, IOException, CannotCompileException
      Writes a class file represented by this CtClass object in the current directory. Once this method is called, further modifications are not possible any more.
      Throws:
      NotFoundException
      IOException
      CannotCompileException
      See Also:

    • writeFile

      public void writeFile(String directoryName) throws CannotCompileException, 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
      IOException
      See Also:

    • 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(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(DataOutputStream out) throws CannotCompileException, 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
      IOException

    • makeUniqueName

      public String makeUniqueName(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.