Package org.apache.bcel.classfile
Class ConstantPool
- java.lang.Object
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- org.apache.bcel.classfile.ConstantPool
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public class ConstantPool extends java.lang.Object implements java.lang.Cloneable, Node, java.lang.Iterable<Constant>
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
,ConstantPoolGen
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Field Summary
Fields Modifier and Type Field Description private Constant[]
constantPool
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Constructor Summary
Constructors Constructor Description ConstantPool(java.io.DataInput input)
Reads constants from given input stream.ConstantPool(Constant[] constantPool)
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description void
accept(Visitor v)
Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.java.lang.String
constantToString(int index, byte tag)
Retrieves constant at 'index' from constant pool and resolve it to a string representation.java.lang.String
constantToString(Constant c)
Resolves constant to a string representation.ConstantPool
copy()
void
dump(java.io.DataOutputStream file)
Dump constant pool to file stream in binary format.private static java.lang.String
escape(java.lang.String str)
<T extends Constant>
TgetConstant(int index)
Gets constant from constant pool.<T extends Constant>
TgetConstant(int index, byte tag)
Gets constant from constant pool and check whether it has the expected type.<T extends Constant>
TgetConstant(int index, byte tag, java.lang.Class<T> castTo)
Gets constant from constant pool and check whether it has the expected type.<T extends Constant>
TgetConstant(int index, java.lang.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.Constant[]
getConstantPool()
java.lang.String
getConstantString(int index, byte tag)
Gets string from constant pool and bypass the indirection of 'ConstantClass' and 'ConstantString' objects.ConstantUtf8
getConstantUtf8(int index)
Gets constant from constant pool and check whether it has the expected type.int
getLength()
java.util.Iterator<Constant>
iterator()
void
setConstant(int index, Constant constant)
void
setConstantPool(Constant[] constantPool)
java.lang.String
toString()
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Field Detail
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constantPool
private Constant[] constantPool
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Constructor Detail
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ConstantPool
public ConstantPool(Constant[] constantPool)
- Parameters:
constantPool
- Array of constants
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ConstantPool
public ConstantPool(java.io.DataInput input) throws java.io.IOException
Reads constants from given input stream.- Parameters:
input
- Input stream- Throws:
java.io.IOException
- if problem in readUnsignedShort or readConstant
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Method Detail
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escape
private static java.lang.String escape(java.lang.String str)
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accept
public void accept(Visitor v)
Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class. I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
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constantToString
public java.lang.String constantToString(Constant c) throws java.lang.IllegalArgumentException
Resolves constant to a string representation.- Parameters:
c
- Constant to be printed- Returns:
- String representation
- Throws:
java.lang.IllegalArgumentException
- if c is unknown constant type
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constantToString
public java.lang.String constantToString(int index, byte tag)
Retrieves constant at 'index' from constant pool and resolve it to a string representation.- Parameters:
index
- of constant in constant pooltag
- expected type- Returns:
- String representation
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copy
public ConstantPool copy()
- Returns:
- deep copy of this constant pool
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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
- if problem in writeShort or dump
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getConstant
public <T extends Constant> T getConstant(int index) throws ClassFormatException
Gets constant from constant pool.- Parameters:
index
- Index in constant pool- Returns:
- Constant value
- Throws:
ClassFormatException
- if index is invalid- See Also:
Constant
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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.- Parameters:
index
- Index in constant pooltag
- Tag of expected constant, i.e., its type- Returns:
- Constant value
- Throws:
ClassFormatException
- if constant type does not match tag- See Also:
Constant
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getConstant
public <T extends Constant> T getConstant(int index, byte tag, java.lang.Class<T> castTo) throws ClassFormatException
Gets constant from constant pool and check whether it has the expected type.- Parameters:
index
- Index in constant pooltag
- Tag of expected constant, i.e., its type- Returns:
- Constant value
- Throws:
ClassFormatException
- if constant type does not match tag- Since:
- 6.6.0
- See Also:
Constant
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getConstant
public <T extends Constant> T getConstant(int index, java.lang.Class<T> castTo) throws ClassFormatException
Gets constant from constant pool.- Type Parameters:
T
- AConstant
subclass- Parameters:
index
- Index in constant poolcastTo
- TheConstant
subclass to cast to.- Returns:
- Constant value
- Throws:
ClassFormatException
- if index is invalid- Since:
- 6.6.0
- See Also:
Constant
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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
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getConstantString
public java.lang.String getConstantString(int index, byte tag) throws java.lang.IllegalArgumentException
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 pooltag
- Tag of expected constant, either ConstantClass or ConstantString- Returns:
- Contents of string reference
- Throws:
java.lang.IllegalArgumentException
- if tag is invalid- See Also:
ConstantClass
,ConstantString
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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
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getLength
public int getLength()
- Returns:
- Length of constant pool.
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iterator
public java.util.Iterator<Constant> iterator()
- Specified by:
iterator
in interfacejava.lang.Iterable<Constant>
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setConstant
public void setConstant(int index, Constant constant)
- Parameters:
constant
- Constant to set
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setConstantPool
public void setConstantPool(Constant[] constantPool)
- Parameters:
constantPool
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toString
public java.lang.String toString()
- Overrides:
toString
in classjava.lang.Object
- Returns:
- String representation.
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