org.apache.bcel.classfile

Class ConstantPool

java.lang.Object

org.apache.bcel.classfile.ConstantPool

All Implemented Interfaces:

java.lang.Cloneable, Node

public class ConstantPool
extends java.lang.Object
implements java.lang.Cloneable, Node

This class represents the constant pool, i.e., a table of constants, of a parsed classfile. It may contain null references, due to the JVM specification that skips an entry after an 8-byte constant (double, long) entry. Those interested in generating constant pools programatically should see ConstantPoolGen.

See Also:

Constant, ConstantPoolGen

Constructor Summary

Constructors

Constructor and Description
ConstantPool(Constant[] constantPool)
ConstantPool(java.io.DataInput input) Reads constants from given input stream.

Method Summary

Modifier and Type	Method and Description
void	accept(Visitor v) Called by objects that are traversing the nodes of the tree implicitely defined by the contents of a Java class.
java.lang.String	constantToString(Constant c) Resolves constant to a string representation.
java.lang.String	constantToString(int index, byte tag) Retrieves constant at `index' from constant pool and resolve it to a string representation.
ConstantPool	copy()
void	dump(java.io.DataOutputStream file) Dump constant pool to file stream in binary format.
Constant	getConstant(int index) Gets constant from constant pool.
Constant	getConstant(int index, byte tag) Gets constant from constant pool and check whether it has the expected type.
Constant[]	getConstantPool()
java.lang.String	getConstantString(int index, byte tag) Gets string from constant pool and bypass the indirection of `ConstantClass' and `ConstantString' objects.
int	getLength()
void	setConstant(int index, Constant constant)
void	setConstantPool(Constant[] constantPool)
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

ConstantPool

public ConstantPool(Constant[] constantPool)

Parameters:

constantPool - Array of constants

ConstantPool

public ConstantPool(java.io.DataInput input)
             throws java.io.IOException,
                    ClassFormatException

Reads constants from given input stream.

Parameters:

input - Input stream

Throws:

java.io.IOException

ClassFormatException

Method Detail

accept

public void accept(Visitor v)

Called by objects that are traversing the nodes of the tree implicitely defined by the contents of a Java class. I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.

Specified by:

accept in interface Node

Parameters:

v - Visitor object

constantToString

public java.lang.String constantToString(Constant c)
                                  throws ClassFormatException

Resolves constant to a string representation.

Parameters:

c - Constant to be printed

Returns:

String representation

Throws:

ClassFormatException

constantToString

public java.lang.String constantToString(int index,
                                         byte tag)
                                  throws ClassFormatException

Retrieves constant at `index' from constant pool and resolve it to a string representation.

Parameters:

index - of constant in constant pool

tag - expected type

Returns:

String representation

Throws:

ClassFormatException

dump

public void dump(java.io.DataOutputStream file)
          throws java.io.IOException

Dump constant pool to file stream in binary format.

Parameters:

file - Output file stream

Throws:

java.io.IOException

getConstant

public Constant getConstant(int index)

Gets constant from constant pool.

Parameters:

index - Index in constant pool

Returns:

Constant value

See Also:

Constant

getConstant

public Constant getConstant(int index,
                            byte tag)
                     throws ClassFormatException

Gets constant from constant pool and check whether it has the expected type.

Parameters:

index - Index in constant pool

tag - Tag of expected constant, i.e., its type

Returns:

Constant value

Throws:

ClassFormatException

See Also:

Constant

getConstantPool

public Constant[] getConstantPool()

Returns:

Array of constants.

See Also:

Constant

getConstantString

public java.lang.String getConstantString(int index,
                                          byte tag)
                                   throws ClassFormatException

Gets string from constant pool and bypass the indirection of `ConstantClass' and `ConstantString' objects. I.e. these classes have an index field that points to another entry of the constant pool of type `ConstantUtf8' which contains the real data.

Parameters:

index - Index in constant pool

tag - Tag of expected constant, either ConstantClass or ConstantString

Returns:

Contents of string reference

Throws:

ClassFormatException

See Also:

ConstantClass, ConstantString

getLength

public int getLength()

Returns:

Length of constant pool.

setConstant

public void setConstant(int index,
                        Constant constant)

Parameters:

constant - Constant to set

setConstantPool

public void setConstantPool(Constant[] constantPool)

Parameters:

constantPool -

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

Returns:

String representation.

copy

public ConstantPool copy()

Returns:

deep copy of this constant pool