Package org.apache.tomcat.util.bcel.classfile

Class ConstantPool

java.lang.Object

org.apache.tomcat.util.bcel.classfile.ConstantPool

public class ConstantPool
extends Object

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 programmatically should see ConstantPoolGen.

See Also:

• Constant

Method Summary

Modifier and Type	Method	Description
<T extends Constant> T	getConstant(int index)	Gets constant from constant pool.
<T extends Constant> T	getConstant(int index, byte tag)	Gets constant from constant pool and check whether it has the expected type.
<T extends Constant> T	getConstant(int index, Class<T> castTo)	Gets constant from constant pool.
ConstantInteger	getConstantInteger(int index)	Gets constant from constant pool and check whether it has the expected type.
ConstantUtf8	getConstantUtf8(int index)	Gets constant from constant pool and check whether it has the expected type.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

getConstant

public <T extends Constant> T getConstant(int index)
                                   throws ClassFormatException

Gets constant from constant pool.

Type Parameters:

T - A Constant subclass

Parameters:

index - Index in constant pool

Returns:

Constant value

Throws:

ClassFormatException - if index is invalid

See Also:

• Constant

getConstant

public <T extends Constant> T getConstant(int index,
 byte tag)
                                   throws ClassFormatException

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

Type Parameters:

T - A Constant subclass

Parameters:

index - Index in constant pool

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

Returns:

Constant value

Throws:

ClassFormatException - if constant type does not match tag

See Also:

• Constant

getConstant

public <T extends Constant> T getConstant(int index,
 Class<T> castTo)
                                   throws ClassFormatException

Gets constant from constant pool.

Type Parameters:

T - A Constant subclass

Parameters:

index - Index in constant pool

castTo - The Constant subclass to cast to.

Returns:

Constant value

Throws:

ClassFormatException - if index is invalid

See Also:

• Constant

getConstantInteger

public ConstantInteger getConstantInteger(int index)

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

Parameters:

index - Index in constant pool

Returns:

ConstantInteger value

Throws:

ClassFormatException - if constant type does not match tag

See Also:

• ConstantInteger

getConstantUtf8

public ConstantUtf8 getConstantUtf8(int index)
                             throws ClassFormatException

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

Parameters:

index - Index in constant pool

Returns:

ConstantUtf8 value

Throws:

ClassFormatException - if constant type does not match tag

See Also:

• ConstantUtf8