Package org.apache.bcel.generic

Class MethodGen

java.lang.Object

org.apache.bcel.classfile.AccessFlags

org.apache.bcel.generic.FieldGenOrMethodGen

org.apache.bcel.generic.MethodGen

All Implemented Interfaces:

Cloneable, NamedAndTyped

public class MethodGen
extends FieldGenOrMethodGen

Template class for building up a method. This is done by defining exception handlers, adding thrown exceptions, local variables and attributes, whereas the 'LocalVariableTable' and 'LineNumberTable' attributes will be set automatically for the code. Use stripAttributes() if you don't like this. While generating code it may be necessary to insert NOP operations. You can use the 'removeNOPs' method to get rid off them. The resulting method object can be obtained via the 'getMethod()' method.

See Also:

• InstructionList
• Method

Field Summary

Fields inherited from class org.apache.bcel.generic.FieldGenOrMethodGen

cp, name, type

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

access_flags

Constructor Summary

Constructors

Constructor	Description
MethodGen(int accessFlags, Type returnType, Type[] argTypes, String[] argNames, String methodName, String className, InstructionList il, ConstantPoolGen cp)	Declare method.
MethodGen(Method method, String className, ConstantPoolGen cp)	Instantiate from existing method.

Method Summary

Modifier and Type	Method	Description
void	addAnnotationsAsAttribute(ConstantPoolGen cp)
void	addCodeAttribute(Attribute a)	Add an attribute to the code.
void	addException(String className)	Add an exception possibly thrown by this method.
CodeExceptionGen	addExceptionHandler(InstructionHandle startPc, InstructionHandle endPc, InstructionHandle handlerPc, ObjectType catchType)	Add an exception handler, i.e., specify region where a handler is active and an instruction where the actual handling is done.
LineNumberGen	addLineNumber(InstructionHandle ih, int srcLine)	Give an instruction a line number corresponding to the source code line.
LocalVariableGen	addLocalVariable(String name, Type type, int slot, InstructionHandle start, InstructionHandle end)	Adds a local variable to this method.
LocalVariableGen	addLocalVariable(String name, Type type, int slot, InstructionHandle start, InstructionHandle end, int origIndex)	Adds a local variable to this method.
LocalVariableGen	addLocalVariable(String name, Type type, InstructionHandle start, InstructionHandle end)	Adds a local variable to this method and assigns an index automatically.
void	addObserver(MethodObserver o)	Add observer for this object.
void	addParameterAnnotation(int parameterIndex, AnnotationEntryGen annotation)
void	addParameterAnnotationsAsAttribute(ConstantPoolGen cp)
MethodGen	copy(String className, ConstantPoolGen cp)
boolean	equals(Object obj)	Return value as defined by given BCELComparator strategy.
List<AnnotationEntryGen>	getAnnotationsOnParameter(int i)	Return a list of AnnotationGen objects representing parameter annotations
String	getArgumentName(int i)
String[]	getArgumentNames()
Type	getArgumentType(int i)
Type[]	getArgumentTypes()
String	getClassName()
Attribute[]	getCodeAttributes()
static BCELComparator<FieldGenOrMethodGen>	getComparator()
CodeExceptionGen[]	getExceptionHandlers()
String[]	getExceptions()
InstructionList	getInstructionList()
LineNumberGen[]	getLineNumbers()
LineNumberTable	getLineNumberTable(ConstantPoolGen cp)
LocalVariableGen[]	getLocalVariables()
LocalVariableTable	getLocalVariableTable(ConstantPoolGen cp)
LocalVariableTypeTable	getLocalVariableTypeTable()
int	getMaxLocals()
int	getMaxStack()
static int	getMaxStack(ConstantPoolGen cp, InstructionList il, CodeExceptionGen[] et)	Computes stack usage of an instruction list by performing control flow analysis.
Method	getMethod()	Gets method object.
Type	getReturnType()
String	getSignature()
int	hashCode()	Return value as defined by given BCELComparator strategy.
void	removeCodeAttribute(Attribute a)	Remove a code attribute.
void	removeCodeAttributes()	Remove all code attributes.
void	removeException(String c)	Remove an exception.
void	removeExceptionHandler(CodeExceptionGen c)	Remove an exception handler.
void	removeExceptionHandlers()	Remove all line numbers.
void	removeExceptions()	Remove all exceptions.
void	removeLineNumber(LineNumberGen l)	Remove a line number.
void	removeLineNumbers()	Remove all line numbers.
void	removeLocalVariable(LocalVariableGen l)	Remove a local variable, its slot will not be reused, if you do not use addLocalVariable with an explicit index argument.
void	removeLocalVariables()	Remove all local variables.
void	removeLocalVariableTypeTable()	Remove the LocalVariableTypeTable
void	removeNOPs()	Remove all NOPs from the instruction list (if possible) and update every object referring to them, i.e., branch instructions, local variables and exception handlers.
void	removeObserver(MethodObserver o)	Remove observer for this object.
void	removeRuntimeAttributes(Attribute[] attributes)	Would prefer to make this private, but need a way to test if client is using BCEL version 6.5.0 or later that contains fix for BCEL-329.
void	setArgumentName(int i, String name)
void	setArgumentNames(String[] argNames)
void	setArgumentType(int i, Type type)
void	setArgumentTypes(Type[] argTypes)
void	setClassName(String className)
static void	setComparator(BCELComparator<FieldGenOrMethodGen> comparator)
void	setInstructionList(InstructionList il)
void	setMaxLocals()	Compute maximum number of local variables.
void	setMaxLocals(int m)	Sets maximum number of local variables.
void	setMaxStack()	Computes max.
void	setMaxStack(int m)	Sets maximum stack size for this method.
void	setReturnType(Type returnType)
void	stripAttributes(boolean flag)	Do not/Do produce attributes code attributesLineNumberTable and LocalVariableTable, like javac -O
final String	toString()	Return string representation close to declaration format, 'public static void main(String[]) throws IOException', e.g.
void	update()	Call notify() method on all observers.

Methods inherited from class org.apache.bcel.generic.FieldGenOrMethodGen

addAll, addAnnotationEntry, addAttribute, clone, getAnnotationEntries, getAttributes, getConstantPool, getName, getType, removeAnnotationEntries, removeAnnotationEntry, removeAttribute, removeAttributes, setConstantPool, setName, setType

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

getAccessFlags, getModifiers, isAbstract, isAbstract, isAnnotation, isAnnotation, isEnum, isEnum, isFinal, isFinal, isInterface, isInterface, isNative, isNative, isPrivate, isPrivate, isProtected, isProtected, isPublic, isPublic, isStatic, isStatic, isStrictfp, isStrictfp, isSynchronized, isSynchronized, isSynthetic, isSynthetic, isTransient, isTransient, isVarArgs, isVarArgs, isVolatile, isVolatile, setAccessFlags, setModifiers

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Details

MethodGen

public MethodGen(int accessFlags,
 Type returnType,
 Type[] argTypes,
 String[] argNames,
 String methodName,
 String className,
 InstructionList il,
 ConstantPoolGen cp)

Declare method. If the method is non-static the constructor automatically declares a local variable '$this' in slot 0. The actual code is contained in the 'il' parameter, which may further manipulated by the user. But they must take care not to remove any instruction (handles) that are still referenced from this object. For example one may not add a local variable and later remove the instructions it refers to without causing havoc. It is safe however if you remove that local variable, too.

Parameters:

accessFlags - access qualifiers

returnType - method type

argTypes - argument types

argNames - argument names (if this is null, default names will be provided for them)

methodName - name of method

className - class name containing this method (may be null, if you don't care)

il - instruction list associated with this method, may be null only for abstract or native methods

cp - constant pool

MethodGen

public MethodGen(Method method,
 String className,
 ConstantPoolGen cp)

Instantiate from existing method.

Parameters:

method - method

className - class name containing this method

cp - constant pool

Method Details

getComparator

public static BCELComparator<FieldGenOrMethodGen> getComparator()

Returns:

Comparison strategy object.

getMaxStack

public static int getMaxStack(ConstantPoolGen cp,
 InstructionList il,
 CodeExceptionGen[] et)

Computes stack usage of an instruction list by performing control flow analysis.

Returns:

maximum stack depth used by method

setComparator

public static void setComparator(BCELComparator<FieldGenOrMethodGen> comparator)

Parameters:

comparator - Comparison strategy object.

addAnnotationsAsAttribute

public void addAnnotationsAsAttribute(ConstantPoolGen cp)

Since:

6.0

addCodeAttribute

public void addCodeAttribute(Attribute a)

Add an attribute to the code. Currently, the JVM knows about the LineNumberTable, LocalVariableTable and StackMap attributes, where the former two will be generated automatically and the latter is used for the MIDP only. Other attributes will be ignored by the JVM but do no harm.

Parameters:

a - attribute to be added

addException

public void addException(String className)

Add an exception possibly thrown by this method.

Parameters:

className - (fully qualified) name of exception

addExceptionHandler

public CodeExceptionGen addExceptionHandler(InstructionHandle startPc,
 InstructionHandle endPc,
 InstructionHandle handlerPc,
 ObjectType catchType)

Add an exception handler, i.e., specify region where a handler is active and an instruction where the actual handling is done.

Parameters:

startPc - Start of region (inclusive)

endPc - End of region (inclusive)

handlerPc - Where handling is done

catchType - class type of handled exception or null if any exception is handled

Returns:

new exception handler object

addLineNumber

public LineNumberGen addLineNumber(InstructionHandle ih,
 int srcLine)

Give an instruction a line number corresponding to the source code line.

Parameters:

ih - instruction to tag

Returns:

new line number object

See Also:

• LineNumber

addLocalVariable

public LocalVariableGen addLocalVariable(String name,
 Type type,
 InstructionHandle start,
 InstructionHandle end)

Adds a local variable to this method and assigns an index automatically.

Parameters:

name - variable name

type - variable type

start - from where the variable is valid, if this is null, it is valid from the start

end - until where the variable is valid, if this is null, it is valid to the end

Returns:

new local variable object

See Also:

• LocalVariable

addLocalVariable

public LocalVariableGen addLocalVariable(String name,
 Type type,
 int slot,
 InstructionHandle start,
 InstructionHandle end)

Adds a local variable to this method.

Parameters:

name - variable name

type - variable type

slot - the index of the local variable, if type is long or double, the next available index is slot+2

start - from where the variable is valid

end - until where the variable is valid

Returns:

new local variable object

See Also:

• LocalVariable

addLocalVariable

public LocalVariableGen addLocalVariable(String name,
 Type type,
 int slot,
 InstructionHandle start,
 InstructionHandle end,
 int origIndex)

Adds a local variable to this method.

Parameters:

name - variable name

type - variable type

slot - the index of the local variable, if type is long or double, the next available index is slot+2

start - from where the variable is valid

end - until where the variable is valid

origIndex - the index of the local variable prior to any modifications

Returns:

new local variable object

See Also:

• LocalVariable

addObserver

public void addObserver(MethodObserver o)

Add observer for this object.

addParameterAnnotation

public void addParameterAnnotation(int parameterIndex,
 AnnotationEntryGen annotation)

addParameterAnnotationsAsAttribute

public void addParameterAnnotationsAsAttribute(ConstantPoolGen cp)

Since:

6.0

copy

public MethodGen copy(String className,
 ConstantPoolGen cp)

Returns:

deep copy of this method

equals

public boolean equals(Object obj)

Return value as defined by given BCELComparator strategy. By default two MethodGen objects are said to be equal when their names and signatures are equal.

Overrides:

equals in class Object

See Also:

• Object.equals(Object)

getAnnotationsOnParameter

public List<AnnotationEntryGen> getAnnotationsOnParameter(int i)

Return a list of AnnotationGen objects representing parameter annotations

Since:

6.0

getArgumentName

public String getArgumentName(int i)

getArgumentNames

public String[] getArgumentNames()

getArgumentType

public Type getArgumentType(int i)

getArgumentTypes

public Type[] getArgumentTypes()

getClassName

public String getClassName()

Returns:

class that contains this method

getCodeAttributes

public Attribute[] getCodeAttributes()

Returns:

all attributes of this method.

getExceptionHandlers

public CodeExceptionGen[] getExceptionHandlers()

getExceptions

public String[] getExceptions()

getInstructionList

public InstructionList getInstructionList()

getLineNumbers

public LineNumberGen[] getLineNumbers()

getLineNumberTable

public LineNumberTable getLineNumberTable(ConstantPoolGen cp)

Returns:

'LineNumberTable' attribute of all the local variables of this method.

getLocalVariables

public LocalVariableGen[] getLocalVariables()

getLocalVariableTable

public LocalVariableTable getLocalVariableTable(ConstantPoolGen cp)

Returns:

'LocalVariableTable' attribute of all the local variables of this method.

getLocalVariableTypeTable

public LocalVariableTypeTable getLocalVariableTypeTable()

Returns:

'LocalVariableTypeTable' attribute of this method.

getMaxLocals

public int getMaxLocals()

getMaxStack

public int getMaxStack()

getMethod

public Method getMethod()

Gets method object. Never forget to call setMaxStack() or setMaxStack(max), respectively, before calling this method (the same applies for max locals).

Returns:

method object

getReturnType

public Type getReturnType()

getSignature

public String getSignature()

Specified by:

getSignature in class FieldGenOrMethodGen

Returns:

signature of method/field.

hashCode

public int hashCode()

Return value as defined by given BCELComparator strategy. By default return the hash code of the method's name XOR signature.

Overrides:

hashCode in class Object

See Also:

• Object.hashCode()

removeCodeAttribute

public void removeCodeAttribute(Attribute a)

Remove a code attribute.

removeCodeAttributes

public void removeCodeAttributes()

Remove all code attributes.

removeException

public void removeException(String c)

Remove an exception.

removeExceptionHandler

public void removeExceptionHandler(CodeExceptionGen c)

Remove an exception handler.

removeExceptionHandlers

public void removeExceptionHandlers()

Remove all line numbers.

removeExceptions

public void removeExceptions()

Remove all exceptions.

removeLineNumber

public void removeLineNumber(LineNumberGen l)

Remove a line number.

removeLineNumbers

public void removeLineNumbers()

Remove all line numbers.

removeLocalVariable

public void removeLocalVariable(LocalVariableGen l)

Remove a local variable, its slot will not be reused, if you do not use addLocalVariable with an explicit index argument.

removeLocalVariables

public void removeLocalVariables()

Remove all local variables.

removeLocalVariableTypeTable

public void removeLocalVariableTypeTable()

Remove the LocalVariableTypeTable

removeNOPs

public void removeNOPs()

Remove all NOPs from the instruction list (if possible) and update every object referring to them, i.e., branch instructions, local variables and exception handlers.

removeObserver

public void removeObserver(MethodObserver o)

Remove observer for this object.

removeRuntimeAttributes

public void removeRuntimeAttributes(Attribute[] attributes)

Would prefer to make this private, but need a way to test if client is using BCEL version 6.5.0 or later that contains fix for BCEL-329.

Since:

6.5.0

setArgumentName

public void setArgumentName(int i,
 String name)

setArgumentNames

public void setArgumentNames(String[] argNames)

setArgumentType

public void setArgumentType(int i,
 Type type)

setArgumentTypes

public void setArgumentTypes(Type[] argTypes)

setClassName

public void setClassName(String className)

setInstructionList

public void setInstructionList(InstructionList il)

setMaxLocals

public void setMaxLocals()

Compute maximum number of local variables.

setMaxLocals

public void setMaxLocals(int m)

Sets maximum number of local variables.

setMaxStack

public void setMaxStack()

Computes max. stack size by performing control flow analysis.

setMaxStack

public void setMaxStack(int m)

Sets maximum stack size for this method.

setReturnType

public void setReturnType(Type returnType)

stripAttributes

public void stripAttributes(boolean flag)

Do not/Do produce attributes code attributesLineNumberTable and LocalVariableTable, like javac -O

toString

public final String toString()

Return string representation close to declaration format, 'public static void main(String[]) throws IOException', e.g.

Overrides:

toString in class Object

Returns:

String representation of the method.

update

public void update()

Call notify() method on all observers. This method is not called automatically whenever the state has changed, but has to be called by the user after they have finished editing the object.