ClassFile (Javassist API)

java.lang.Object
- javassist.bytecode.ClassFile

public final class ClassFile
extends java.lang.Object

ClassFile represents a Java .class file, which consists of a constant pool, methods, fields, and attributes.

For example,

 ClassFile cf = new ClassFile(false, "test.Foo", null);
 cf.setInterfaces(new String[] { "java.lang.Cloneable" });

 FieldInfo f = new FieldInfo(cf.getConstPool(), "width", "I");
 f.setAccessFlags(AccessFlag.PUBLIC);
 cf.addField(f);

 cf.write(new DataOutputStream(new FileOutputStream("Foo.class")));

This code generates a class file Foo.class for the following class:

 package test;
 class Foo implements Cloneable {
     public int width;
 }

See Also:: FieldInfo, MethodInfo, ClassFileWriter, CtClass.getClassFile(), ClassPool.makeClass(ClassFile)

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`JAVA_1` The major version number of class files for JDK 1.1.
`static int`	`JAVA_2` The major version number of class files for JDK 1.2.
`static int`	`JAVA_3` The major version number of class files for JDK 1.3.
`static int`	`JAVA_4` The major version number of class files for JDK 1.4.
`static int`	`JAVA_5` The major version number of class files for JDK 1.5.
`static int`	`JAVA_6` The major version number of class files for JDK 1.6.
`static int`	`JAVA_7` The major version number of class files for JDK 1.7.
`static int`	`JAVA_8` The major version number of class files for JDK 1.8.
`static int`	`MAJOR_VERSION` The major version number of class files created from scratch.

Constructor Summary

Constructors
Constructor and Description
`ClassFile(boolean isInterface, java.lang.String classname, java.lang.String superclass)` Constructs a class file including no members.
`ClassFile(java.io.DataInputStream in)` Constructs a class file from a byte stream.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`addAttribute(AttributeInfo info)` Appends an attribute.
`void`	`addField(FieldInfo finfo)` Appends a field to the class.
`void`	`addField2(FieldInfo finfo)` Just appends a field to the class.
`void`	`addInterface(java.lang.String name)` Appends an interface to the interfaces implemented by the class.
`void`	`addMethod(MethodInfo minfo)` Appends a method to the class.
`void`	`addMethod2(MethodInfo minfo)` Just appends a method to the class.
`void`	`compact()` Eliminates dead constant pool items.
`int`	`getAccessFlags()` Returns access flags.
`AttributeInfo`	`getAttribute(java.lang.String name)` Returns the attribute with the specified name.
`java.util.List`	`getAttributes()` Returns all the attributes.
`ConstPool`	`getConstPool()` Returns a constant pool table.
`java.util.List`	`getFields()` Returns all the fields declared in the class.
`int`	`getInnerAccessFlags()` Returns access and property flags of this nested class.
`java.lang.String[]`	`getInterfaces()` Returns the names of the interfaces implemented by the class.
`int`	`getMajorVersion()` Get the Major version.
`MethodInfo`	`getMethod(java.lang.String name)` Returns the method with the specified name.
`java.util.List`	`getMethods()` Returns all the methods declared in the class.
`int`	`getMinorVersion()` Get the minor version.
`java.lang.String`	`getName()` Returns the class name.
`void`	`getRefClasses(java.util.Map classnames)` Internal-use only.
`java.lang.String`	`getSourceFile()` Returns the source file containing this class.
`MethodInfo`	`getStaticInitializer()` Returns a static initializer (class initializer), or null if it does not exist.
`java.lang.String`	`getSuperclass()` Returns the super class name.
`int`	`getSuperclassId()` Returns the index of the constant pool entry representing the super class.
`boolean`	`isAbstract()` Returns true if this is an abstract class or an interface.
`boolean`	`isFinal()` Returns true if this is a final class or interface.
`boolean`	`isInterface()` Returns true if this is an interface.
`void`	`prune()` Discards all attributes, associated with both the class file and the members such as a code attribute and exceptions attribute.
`void`	`renameClass(java.util.Map classnames)` Replaces all occurrences of several class names in the class file.
`void`	`renameClass(java.lang.String oldname, java.lang.String newname)` Replaces all occurrences of a class name in the class file.
`void`	`setAccessFlags(int acc)` Changes access flags.
`void`	`setInterfaces(java.lang.String[] nameList)` Sets the interfaces.
`void`	`setMajorVersion(int major)` Set the major version.
`void`	`setMinorVersion(int minor)` Set the minor version.
`void`	`setName(java.lang.String name)` Sets the class name.
`void`	`setSuperclass(java.lang.String superclass)` Sets the super class.
`void`	`setVersionToJava5()` Sets the major and minor version to Java 5.
`void`	`write(java.io.DataOutputStream out)` Writes a class file represented by this object into an output stream.

Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - JAVA_1
```
public static final int JAVA_1
```
    The major version number of class files for JDK 1.1.
    
    See Also:
    
    Constant Field Values
  - JAVA_2
```
public static final int JAVA_2
```
    The major version number of class files for JDK 1.2.
    
    See Also:
    
    Constant Field Values
  - JAVA_3
```
public static final int JAVA_3
```
    The major version number of class files for JDK 1.3.
    
    See Also:
    
    Constant Field Values
  - JAVA_4
```
public static final int JAVA_4
```
    The major version number of class files for JDK 1.4.
    
    See Also:
    
    Constant Field Values
  - JAVA_5
```
public static final int JAVA_5
```
    The major version number of class files for JDK 1.5.
    
    See Also:
    
    Constant Field Values
  - JAVA_6
```
public static final int JAVA_6
```
    The major version number of class files for JDK 1.6.
    
    See Also:
    
    Constant Field Values
  - JAVA_7
```
public static final int JAVA_7
```
    The major version number of class files for JDK 1.7.
    
    See Also:
    
    Constant Field Values
  - JAVA_8
```
public static final int JAVA_8
```
    The major version number of class files for JDK 1.8.
    
    See Also:
    
    Constant Field Values
  - MAJOR_VERSION
```
public static int MAJOR_VERSION
```
    The major version number of class files created from scratch. The default value is 47 (JDK 1.3). It is 49 (JDK 1.5) if the JVM supports java.lang.StringBuilder. It is 50 (JDK 1.6) if the JVM supports java.util.zip.DeflaterInputStream. It is 51 (JDK 1.7) if the JVM supports java.lang.invoke.CallSite.
- Constructor Detail
  - ClassFile
```
public ClassFile(java.io.DataInputStream in)
          throws java.io.IOException
```
    Constructs a class file from a byte stream.
    
    Throws:
    
    java.io.IOException
  - ClassFile
```
public ClassFile(boolean isInterface,
                 java.lang.String classname,
                 java.lang.String superclass)
```
    Constructs a class file including no members.
    
    Parameters:
    
    isInterface - true if this is an interface. false if this is a class.
    
    classname - a fully-qualified class name
    
    superclass - a fully-qualified super class name or null.
- Method Detail
  - compact
```
public void compact()
```
    Eliminates dead constant pool items. If a method or a field is removed, the constant pool items used by that method/field become dead items. This method recreates a constant pool.
  - prune
```
public void prune()
```
    Discards all attributes, associated with both the class file and the members such as a code attribute and exceptions attribute. The unused constant pool entries are also discarded (a new packed constant pool is constructed).
  - getConstPool
```
public ConstPool getConstPool()
```
    Returns a constant pool table.
  - isInterface
```
public boolean isInterface()
```
    Returns true if this is an interface.
  - isFinal
```
public boolean isFinal()
```
    Returns true if this is a final class or interface.
  - isAbstract
```
public boolean isAbstract()
```
    Returns true if this is an abstract class or an interface.
  - getAccessFlags
```
public int getAccessFlags()
```
    Returns access flags.
    
    See Also:
    
    AccessFlag
  - setAccessFlags
```
public void setAccessFlags(int acc)
```
    Changes access flags.
    
    See Also:
    
    AccessFlag
  - getInnerAccessFlags
```
public int getInnerAccessFlags()
```
    Returns access and property flags of this nested class. This method returns -1 if the class is not a nested class.
    The returned value is obtained from inner_class_access_flags of the entry representing this nested class itself in InnerClasses_attribute.
  - getName
```
public java.lang.String getName()
```
    Returns the class name.
  - setName
```
public void setName(java.lang.String name)
```
    Sets the class name. This method substitutes the new name for all occurrences of the old class name in the class file.
  - getSuperclass
```
public java.lang.String getSuperclass()
```
    Returns the super class name.
  - getSuperclassId
```
public int getSuperclassId()
```
    Returns the index of the constant pool entry representing the super class.
  - setSuperclass
```
public void setSuperclass(java.lang.String superclass)
                   throws CannotCompileException
```
    Sets the super class.
    The new super class should inherit from the old super class. This method modifies constructors so that they call constructors declared in the new super class.
    
    Throws:
    
    CannotCompileException
  - renameClass
```
public final void renameClass(java.lang.String oldname,
                              java.lang.String newname)
```
    Replaces all occurrences of a class name in the class file.
    If class X is substituted for class Y in the class file, X and Y must have the same signature. If Y provides a method m(), X must provide it even if X inherits m() from the super class. If this fact is not guaranteed, the bytecode verifier may cause an error.
    
    Parameters:
    
    oldname - the replaced class name
    
    newname - the substituted class name
  - renameClass
```
public final void renameClass(java.util.Map classnames)
```
    Replaces all occurrences of several class names in the class file.
    
    Parameters:
    
    classnames - specifies which class name is replaced with which new name. Class names must be described with the JVM-internal representation like java/lang/Object.
    
    See Also:
    
    renameClass(String,String)
  - getRefClasses
```
public final void getRefClasses(java.util.Map classnames)
```
    Internal-use only. CtClass.getRefClasses() calls this method.
  - getInterfaces
```
public java.lang.String[] getInterfaces()
```
    Returns the names of the interfaces implemented by the class. The returned array is read only.
  - setInterfaces
```
public void setInterfaces(java.lang.String[] nameList)
```
    Sets the interfaces.
    
    Parameters:
    
    nameList - the names of the interfaces.
  - addInterface
```
public void addInterface(java.lang.String name)
```
    Appends an interface to the interfaces implemented by the class.
  - getFields
```
public java.util.List getFields()
```
    Returns all the fields declared in the class.
    
    Returns:
    
    a list of FieldInfo.
    
    See Also:
    
    FieldInfo
  - addField
```
public void addField(FieldInfo finfo)
              throws DuplicateMemberException
```
    Appends a field to the class.
    
    Throws:
    
    DuplicateMemberException - when the field is already included.
  - addField2
```
public final void addField2(FieldInfo finfo)
```
    Just appends a field to the class. It does not check field duplication. Use this method only when minimizing performance overheads is seriously required.
    
    Since:
    
    3.13
  - getMethods
```
public java.util.List getMethods()
```
    Returns all the methods declared in the class.
    
    Returns:
    
    a list of MethodInfo.
    
    See Also:
    
    MethodInfo
  - getMethod
```
public MethodInfo getMethod(java.lang.String name)
```
    Returns the method with the specified name. If there are multiple methods with that name, this method returns one of them.
    
    Returns:
    
    null if no such method is found.
  - getStaticInitializer
```
public MethodInfo getStaticInitializer()
```
    Returns a static initializer (class initializer), or null if it does not exist.
  - addMethod
```
public void addMethod(MethodInfo minfo)
               throws DuplicateMemberException
```
    Appends a method to the class. If there is a bridge method with the same name and signature, then the bridge method is removed before a new method is added.
    
    Throws:
    
    DuplicateMemberException - when the method is already included.
  - addMethod2
```
public final void addMethod2(MethodInfo minfo)
```
    Just appends a method to the class. It does not check method duplication or remove a bridge method. Use this method only when minimizing performance overheads is seriously required.
    
    Since:
    
    3.13
  - getAttributes
```
public java.util.List getAttributes()
```
    Returns all the attributes. The returned List object is shared with this object. If you add a new attribute to the list, the attribute is also added to the classs file represented by this object. If you remove an attribute from the list, it is also removed from the class file.
    
    Returns:
    
    a list of AttributeInfo objects.
    
    See Also:
    
    AttributeInfo
  - getAttribute
```
public AttributeInfo getAttribute(java.lang.String name)
```
    Returns the attribute with the specified name. If there are multiple attributes with that name, this method returns either of them. It returns null if the specified attributed is not found.
    
    Parameters:
    
    name - attribute name
    
    See Also:
    
    getAttributes()
  - addAttribute
```
public void addAttribute(AttributeInfo info)
```
    Appends an attribute. If there is already an attribute with the same name, the new one substitutes for it.
    
    See Also:
    
    getAttributes()
  - getSourceFile
```
public java.lang.String getSourceFile()
```
    Returns the source file containing this class.
    
    Returns:
    
    null if this information is not available.
  - write
```
public void write(java.io.DataOutputStream out)
           throws java.io.IOException
```
    Writes a class file represented by this object into an output stream.
    
    Throws:
    
    java.io.IOException
  - getMajorVersion
```
public int getMajorVersion()
```
    Get the Major version.
    
    Returns:
    
    the major version
  - setMajorVersion
```
public void setMajorVersion(int major)
```
    Set the major version.
    
    Parameters:
    
    major - the major version
  - getMinorVersion
```
public int getMinorVersion()
```
    Get the minor version.
    
    Returns:
    
    the minor version
  - setMinorVersion
```
public void setMinorVersion(int minor)
```
    Set the minor version.
    
    Parameters:
    
    minor - the minor version
  - setVersionToJava5
```
public void setVersionToJava5()
```
    Sets the major and minor version to Java 5. If the major version is older than 49, Java 5 extensions such as annotations are ignored by the JVM.

Class ClassFile

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

JAVA_1

JAVA_2

JAVA_3

JAVA_4

JAVA_5

JAVA_6

JAVA_7

JAVA_8

MAJOR_VERSION

Constructor Detail

ClassFile

ClassFile

Method Detail

compact

prune

getConstPool

isInterface

isFinal

isAbstract

getAccessFlags

setAccessFlags

getInnerAccessFlags

getName

setName

getSuperclass

getSuperclassId

setSuperclass

renameClass

renameClass

getRefClasses

getInterfaces

setInterfaces

addInterface

getFields

addField

addField2

getMethods

getMethod

getStaticInitializer

addMethod

addMethod2

getAttributes

getAttribute

addAttribute

getSourceFile

write

getMajorVersion

setMajorVersion

getMinorVersion

setMinorVersion

setVersionToJava5