Package javassist

Class CtField

java.lang.Object

javassist.CtMember

javassist.CtField

public class CtField
extends CtMember

An instance of CtField represents a field.

See Also:

• CtClass.getDeclaredFields()

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	CtField.Initializer	Instances of this class specify how to initialize a field.

Constructor Summary

Constructors

Constructor	Description
CtField(CtClass type, String name, CtClass declaring)	Creates a CtField object.
CtField(CtField src, CtClass declaring)	Creates a copy of the given field.

Method Summary

Modifier and Type	Method	Description
Object	getAnnotation(Class<?> clz)	Returns the annotation if the class has the specified annotation class.
Object[]	getAnnotations()	Returns the annotations associated with this field.
byte[]	getAttribute(String name)	Obtains an attribute with the given name.
Object[]	getAvailableAnnotations()	Returns the annotations associated with this field.
Object	getConstantValue()	Returns the value of this field if it is a constant field.
CtClass	getDeclaringClass()	Returns the class declaring the field.
FieldInfo	getFieldInfo()	Returns the FieldInfo representing the field in the class file.
FieldInfo	getFieldInfo2()	Returns the FieldInfo representing the field in the class file (read only).
String	getGenericSignature()	Returns the generic signature of the field.
int	getModifiers()	Returns the encoded modifiers of the field.
String	getName()	Returns the name of the field.
String	getSignature()	Returns the character string representing the type of the field.
CtClass	getType()	Returns the type of the field.
boolean	hasAnnotation(String typeName)	Returns true if the class has the specified annotation type.
static CtField	make(String src, CtClass declaring)	Compiles the given source code and creates a field.
void	setAttribute(String name, byte[] data)	Adds an attribute.
void	setGenericSignature(String sig)	Set the generic signature of the field.
void	setModifiers(int mod)	Sets the encoded modifiers of the field.
void	setName(String newName)	Changes the name of the field.
void	setType(CtClass clazz)	Sets the type of the field.
String	toString()	Returns a String representation of the object.

Methods inherited from class javassist.CtMember

hasAnnotation, visibleFrom

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Details

CtField

public CtField(CtClass type,
 String name,
 CtClass declaring)
        throws CannotCompileException

Creates a CtField object. The created field must be added to a class with CtClass.addField(). An initial value of the field is specified by a CtField.Initializer object.

If getter and setter methods are needed, call CtNewMethod.getter() and CtNewMethod.setter().

Parameters:

type - field type

name - field name

declaring - the class to which the field will be added.

Throws:

CannotCompileException

See Also:

• CtClass.addField(CtField)
• CtNewMethod.getter(String,CtField)
• CtNewMethod.setter(String,CtField)
• CtField.Initializer

CtField

public CtField(CtField src,
 CtClass declaring)
        throws CannotCompileException

Creates a copy of the given field. The created field must be added to a class with CtClass.addField(). An initial value of the field is specified by a CtField.Initializer object.

If getter and setter methods are needed, call CtNewMethod.getter() and CtNewMethod.setter().

Parameters:

src - the original field

declaring - the class to which the field will be added.

Throws:

CannotCompileException

See Also:

• CtNewMethod.getter(String,CtField)
• CtNewMethod.setter(String,CtField)
• CtField.Initializer

Method Details

toString

public String toString()

Returns a String representation of the object.

Overrides:

toString in class CtMember

make

public static CtField make(String src,
 CtClass declaring)
                    throws CannotCompileException

Compiles the given source code and creates a field. Examples of the source code are:

 "public String name;"
 "public int k = 3;"

Note that the source code ends with ';' (semicolon).

Parameters:

src - the source text.

declaring - the class to which the created field is added.

Throws:

CannotCompileException

getFieldInfo

public FieldInfo getFieldInfo()

Returns the FieldInfo representing the field in the class file.

getFieldInfo2

public FieldInfo getFieldInfo2()

Returns the FieldInfo representing the field in the class file (read only). Normal applications do not need calling this method. Use getFieldInfo().

The FieldInfo 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 in CtClass.

This method is available even if the CtClass containing this field is frozen. However, if the class is frozen, the FieldInfo might be also pruned.

See Also:

• getFieldInfo()
• CtClass.isFrozen()
• CtClass.prune()

getDeclaringClass

public CtClass getDeclaringClass()

Returns the class declaring the field.

Overrides:

getDeclaringClass in class CtMember

getName

public String getName()

Returns the name of the field.

Specified by:

getName in class CtMember

See Also:

• CtConstructor.getName()

setName

public void setName(String newName)

Changes the name of the field.

getModifiers

public int getModifiers()

Returns the encoded modifiers of the field.

Specified by:

getModifiers in class CtMember

Returns:

modifiers encoded with javassist.Modifier.

See Also:

• Modifier

setModifiers

public void setModifiers(int mod)

Sets the encoded modifiers of the field.

Specified by:

setModifiers in class CtMember

See Also:

• Modifier

hasAnnotation

public boolean hasAnnotation(String typeName)

Returns true if the class has the specified annotation type.

Specified by:

hasAnnotation in class CtMember

Parameters:

typeName - 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 class. For example, if an annotation @Author is associated with this field, an Author object is returned. The member values can be obtained by calling methods on the Author object.

Specified by:

getAnnotation in class CtMember

Parameters:

clz - the annotation class.

Returns:

the annotation if found, otherwise null.

Throws:

ClassNotFoundException

Since:

3.11

getAnnotations

public Object[] getAnnotations()
                        throws ClassNotFoundException

Returns the annotations associated with this field.

Specified by:

getAnnotations in class CtMember

Returns:

an array of annotation-type objects.

Throws:

ClassNotFoundException

Since:

3.1

See Also:

• getAvailableAnnotations()

getAvailableAnnotations

public Object[] getAvailableAnnotations()

Returns the annotations associated with this field. If any annotations are not on the classpath, they are not included in the returned array.

Specified by:

getAvailableAnnotations in class CtMember

Returns:

an array of annotation-type objects.

Since:

3.3

See Also:

• getAnnotations()

getSignature

public String getSignature()

Returns the character string representing the type of the field. The field signature is represented by a character string called a field descriptor, which is defined in the JVM specification. If two fields have the same type, getSignature() returns the same string.

Note that the returned string is not the type signature contained in the SignatureAttirbute. It is a descriptor.

Specified by:

getSignature in class CtMember

See Also:

• Descriptor
• getGenericSignature()

getGenericSignature

public String getGenericSignature()

Returns the generic signature of the field. It represents a type including type variables.

Specified by:

getGenericSignature in class CtMember

Since:

3.17

See Also:

• SignatureAttribute.toFieldSignature(String)

setGenericSignature

public void setGenericSignature(String sig)

Set the generic signature of the field. It represents a type including type variables. See CtClass.setGenericSignature(String) for a code sample.

Specified by:

setGenericSignature in class CtMember

Parameters:

sig - a new generic signature.

Since:

3.17

See Also:

• SignatureAttribute.ObjectType.encode()

getType

public CtClass getType()
                throws NotFoundException

Returns the type of the field.

Throws:

NotFoundException

setType

public void setType(CtClass clazz)

Sets the type of the field.

This method does not automatically update method bodies that access this field. They have to be explicitly updated. For example, if some method contains an expression t.value and the type of the variable t is changed by setType(CtClass) from int to double, then t.value has to be modified as well since the bytecode of t.value contains the type information.

See Also:

• CodeConverter
• ExprEditor

getConstantValue

public Object getConstantValue()

Returns the value of this field if it is a constant field. This method works only if the field type is a primitive type or String type. Otherwise, it returns null. A constant field is static and final.

Returns:

a Integer, Long, Float, Double, Boolean, or String object representing the constant value. null if it is not a constant field or if the field type is not a primitive type or String.

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.

Note that an attribute is a data block specified by the class file format. See AttributeInfo.

Specified by:

getAttribute in class CtMember

Parameters:

name - attribute name

setAttribute

public void setAttribute(String name,
 byte[] data)

Adds an attribute. The attribute is saved in the class file.

Note that an attribute is a data block specified by the class file format. See AttributeInfo.

Specified by:

setAttribute in class CtMember

Parameters:

name - attribute name

data - attribute value