Package org.apache.bcel.classfile

Class Code

java.lang.Object

org.apache.bcel.classfile.Attribute

org.apache.bcel.classfile.Code

All Implemented Interfaces:

java.lang.Cloneable, Node

public final class Code
extends Attribute

This class represents a chunk of Java byte code contained in a method. It is instantiated by the Attribute.readAttribute() method. A Code attribute contains informations about operand stack, local variables, byte code and the exceptions handled within this method. This attribute has attributes itself, namely LineNumberTable which is used for debugging purposes and LocalVariableTable which contains information about the local variables.

 Code_attribute {
   u2 attribute_name_index;
   u4 attribute_length;
   u2 max_stack;
   u2 max_locals;
   u4 code_length;
   u1 code[code_length];
   u2 exception_table_length;
   {
     u2 start_pc;
     u2 end_pc;
     u2 handler_pc;
     u2 catch_type;
   } exception_table[exception_table_length];
   u2 attributes_count;
   attribute_info attributes[attributes_count];
 }
 

See Also:

Attribute, CodeException, LineNumberTable, LocalVariableTable

Field Summary

Fields

Modifier and Type	Field	Description
private Attribute[]	attributes
private byte[]	code
private CodeException[]	exceptionTable
private int	maxLocals
private int	maxStack

Fields inherited from class org.apache.bcel.classfile.Attribute

constant_pool, EMPTY_ARRAY, length, name_index, tag

Constructor Summary

Constructors

Constructor	Description
Code(int nameIndex, int length, int maxStack, int maxLocals, byte[] code, CodeException[] exceptionTable, Attribute[] attributes, ConstantPool constantPool)	Constructs a Code attribute.
Code(int nameIndex, int length, java.io.DataInput dataInput, ConstantPool constantPool)	Constructs a Code attribute object from a DataInput.
Code(Code code)	Initialize from another object.

Method Summary

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.
private int	calculateLength()
Attribute	copy(ConstantPool constantPool)	Creates a deep copy of this attribute.
void	dump(java.io.DataOutputStream file)	Dumps code attribute to file stream in binary format.
Attribute[]	getAttributes()	Gets the collection of code attributes.
byte[]	getCode()	Gets the actual byte code of the method.
CodeException[]	getExceptionTable()	Gets the table of handled exceptions.
private int	getInternalLength()	Gets the internal length of this code attribute (minus the first 6 bytes) and excluding all its attributes.
LineNumberTable	getLineNumberTable()	Gets the LineNumberTable of Code, if it has one.
LocalVariableTable	getLocalVariableTable()	Gets the LocalVariableTable of Code, if it has one.
LocalVariableTypeTable	getLocalVariableTypeTable()	Gets the local variable type table attribute LocalVariableTypeTable.
int	getMaxLocals()	Gets the number of local variables.
int	getMaxStack()	Gets the maximum size of stack used by this method.
StackMap	getStackMap()	Finds the attribute of StackMap instance.
void	setAttributes(Attribute[] attributes)	Sets the attributes for this Code.
void	setCode(byte[] code)	Sets the byte code.
void	setExceptionTable(CodeException[] exceptionTable)	Sets the exception table.
void	setMaxLocals(int maxLocals)	Sets the maximum number of local variables.
void	setMaxStack(int maxStack)	Sets the maximum stack size.
java.lang.String	toString()
java.lang.String	toString(boolean verbose)	Converts this object to a String.

Methods inherited from class org.apache.bcel.classfile.Attribute

addAttributeReader, addAttributeReader, clone, getConstantPool, getLength, getName, getNameIndex, getTag, println, readAttribute, readAttribute, removeAttributeReader, setConstantPool, setLength, setNameIndex

Methods inherited from class java.lang.Object

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

Field Detail

maxStack

private int maxStack

maxLocals

private int maxLocals

code

private byte[] code

exceptionTable

private CodeException[] exceptionTable

attributes

private Attribute[] attributes

Constructor Detail

Code

public Code(Code code)

Initialize from another object. Note that both objects use the same references (shallow copy). Use copy() for a physical copy.

Parameters:

code - The source Code.

Code

Code(int nameIndex,
     int length,
     java.io.DataInput dataInput,
     ConstantPool constantPool)
throws java.io.IOException

Constructs a Code attribute object from a DataInput.

Parameters:

nameIndex - Index pointing to the name Code.

length - Content length in bytes.

dataInput - Data input.

constantPool - Array of constants.

Throws:

ClassFormatException - if the code array read from file is greater than Const.MAX_CODE_SIZE.

java.io.IOException

Code

public Code(int nameIndex,
            int length,
            int maxStack,
            int maxLocals,
            byte[] code,
            CodeException[] exceptionTable,
            Attribute[] attributes,
            ConstantPool constantPool)

Constructs a Code attribute.

Parameters:

nameIndex - Index pointing to the name Code.

length - Content length in bytes.

maxStack - Maximum size of stack.

maxLocals - Number of local variables.

code - Actual byte code.

exceptionTable - of handled exceptions.

attributes - Attributes of code: LineNumber or LocalVariable.

constantPool - Array of constants.

Throws:

ClassFormatException - if the code array is greater than Const.MAX_CODE_SIZE.

Method Detail

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. That is, the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.

Specified by:

accept in interface Node

Specified by:

accept in class Attribute

Parameters:

v - Visitor object.

calculateLength

private int calculateLength()

Returns:

the full size of this code attribute, minus its first 6 bytes, including the size of all its contained attributes.

copy

public Attribute copy(ConstantPool constantPool)

Creates a deep copy of this attribute.

Specified by:

copy in class Attribute

Parameters:

constantPool - the constant pool to duplicate.

Returns:

deep copy of this attribute.

dump

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

Dumps code attribute to file stream in binary format.

Overrides:

dump in class Attribute

Parameters:

file - Output file stream.

Throws:

java.io.IOException - if an I/O error occurs.

getAttributes

public Attribute[] getAttributes()

Gets the collection of code attributes.

Returns:

Collection of code attributes.

See Also:

Attribute

getCode

public byte[] getCode()

Gets the actual byte code of the method.

Returns:

Actual byte code of the method.

getExceptionTable

public CodeException[] getExceptionTable()

Gets the table of handled exceptions.

Returns:

Table of handled exceptions.

See Also:

CodeException

getInternalLength

private int getInternalLength()

Gets the internal length of this code attribute (minus the first 6 bytes) and excluding all its attributes.

Returns:

the internal length of this code attribute (minus the first 6 bytes) and excluding all its attributes.

getLineNumberTable

public LineNumberTable getLineNumberTable()

Gets the LineNumberTable of Code, if it has one.

Returns:

LineNumberTable of Code, if it has one.

getLocalVariableTable

public LocalVariableTable getLocalVariableTable()

Gets the LocalVariableTable of Code, if it has one.

Returns:

LocalVariableTable of Code, if it has one.

getLocalVariableTypeTable

public LocalVariableTypeTable getLocalVariableTypeTable()

Gets the local variable type table attribute LocalVariableTypeTable.

Returns:

LocalVariableTypeTable of Code, if it has one, null otherwise.

Since:

6.10.0

getMaxLocals

public int getMaxLocals()

Gets the number of local variables.

Returns:

Number of local variables.

getMaxStack

public int getMaxStack()

Gets the maximum size of stack used by this method.

Returns:

Maximum size of stack used by this method.

getStackMap

public StackMap getStackMap()

Finds the attribute of StackMap instance.

Returns:

StackMap of Code, if it has one, else null.

Since:

6.8.0

setAttributes

public void setAttributes(Attribute[] attributes)

Sets the attributes for this Code.

Parameters:

attributes - the attributes to set for this Code.

setCode

public void setCode(byte[] code)

Sets the byte code.

Parameters:

code - byte code.

Throws:

ClassFormatException - if the code array is greater than Const.MAX_CODE_SIZE.

setExceptionTable

public void setExceptionTable(CodeException[] exceptionTable)

Sets the exception table.

Parameters:

exceptionTable - exception table.

setMaxLocals

public void setMaxLocals(int maxLocals)

Sets the maximum number of local variables.

Parameters:

maxLocals - maximum number of local variables.

setMaxStack

public void setMaxStack(int maxStack)

Sets the maximum stack size.

Parameters:

maxStack - maximum stack size.

toString

public java.lang.String toString()

Overrides:

toString in class Attribute

Returns:

String representation of code chunk.

toString

public java.lang.String toString(boolean verbose)

Converts this object to a String.

Parameters:

verbose - Provides verbose output when true.

Returns:

String representation of code chunk.