Package org.apache.bcel.classfile

Class Code

java.lang.Object

org.apache.bcel.classfile.Attribute

org.apache.bcel.classfile.Code

All Implemented Interfaces:

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 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)
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.
Attribute	copy(ConstantPool constantPool)
void	dump(DataOutputStream file)	Dump code attribute to file stream in binary format.
Attribute[]	getAttributes()
byte[]	getCode()
CodeException[]	getExceptionTable()
LineNumberTable	getLineNumberTable()
LocalVariableTable	getLocalVariableTable()
LocalVariableTypeTable	getLocalVariableTypeTable()	Gets the local variable type table attribute LocalVariableTypeTable.
int	getMaxLocals()
int	getMaxStack()
StackMap	getStackMap()	Finds the attribute of StackMap instance.
void	setAttributes(Attribute[] attributes)
void	setCode(byte[] code)
void	setExceptionTable(CodeException[] exceptionTable)
void	setMaxLocals(int maxLocals)
void	setMaxStack(int maxStack)
String	toString()
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

Constructor Details

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

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

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

Method Details

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.

Specified by:

accept in interface Node

Specified by:

accept in class Attribute

Parameters:

v - Visitor object

copy

public Attribute copy(ConstantPool constantPool)

Specified by:

copy in class Attribute

Parameters:

constantPool - the constant pool to duplicate

Returns:

deep copy of this attribute

dump

public void dump(DataOutputStream file)
          throws IOException

Dump code attribute to file stream in binary format.

Overrides:

dump in class Attribute

Parameters:

file - Output file stream

Throws:

IOException - if an I/O error occurs.

getAttributes

public Attribute[] getAttributes()

Returns:

Collection of code attributes.

See Also:

• Attribute

getCode

public byte[] getCode()

Returns:

Actual byte code of the method.

getExceptionTable

public CodeException[] getExceptionTable()

Returns:

Table of handled exceptions.

See Also:

• CodeException

getLineNumberTable

public LineNumberTable getLineNumberTable()

Returns:

LineNumberTable of Code, if it has one

getLocalVariableTable

public LocalVariableTable getLocalVariableTable()

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()

Returns:

Number of local variables.

getMaxStack

public int getMaxStack()

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)

Parameters:

attributes - the attributes to set for this Code

setCode

public void setCode(byte[] code)

Parameters:

code - byte code

setExceptionTable

public void setExceptionTable(CodeException[] exceptionTable)

Parameters:

exceptionTable - exception table

setMaxLocals

public void setMaxLocals(int maxLocals)

Parameters:

maxLocals - maximum number of local variables

setMaxStack

public void setMaxStack(int maxStack)

Parameters:

maxStack - maximum stack size

toString

public String toString()

Overrides:

toString in class Attribute

Returns:

String representation of code chunk.

toString

public String toString(boolean verbose)

Converts this object to a String.

Parameters:

verbose - Provides verbose output when true.

Returns:

String representation of code chunk.