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:

  • Constructor Details

    • MethodGen

      public MethodGen(int access_flags, Type return_type, Type[] argTypes, String[] argNames, String method_name, 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 he 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:
      access_flags - access qualifiers
      return_type - method type
      argTypes - argument types
      argNames - argument names (if this is null, default names will be provided for them)
      method_name - 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

    • addLocalVariable

      public LocalVariableGen addLocalVariable(String name, Type type, int slot, InstructionHandle start, InstructionHandle end, int orig_index)
      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
      orig_index - the index of the local variable prior to any modifications
      Returns:
      new local variable object
      See Also:

    • 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:

    • 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:

    • 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.

    • 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.

    • 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:

    • removeLineNumber

      public void removeLineNumber(LineNumberGen l)
      Remove a line number.

    • removeLineNumbers

      public void removeLineNumbers()
      Remove all line numbers.

    • getLineNumbers

      public LineNumberGen[] getLineNumbers()

    • getLineNumberTable

      public LineNumberTable getLineNumberTable(ConstantPoolGen cp)
      Returns:
      `LineNumberTable' attribute of all the local variables of this method.

    • addExceptionHandler

      public CodeExceptionGen addExceptionHandler(InstructionHandle start_pc, InstructionHandle end_pc, InstructionHandle handler_pc, ObjectType catch_type)
      Add an exception handler, i.e., specify region where a handler is active and an instruction where the actual handling is done.
      Parameters:
      start_pc - Start of region (inclusive)
      end_pc - End of region (inclusive)
      handler_pc - Where handling is done
      catch_type - class type of handled exception or null if any exception is handled
      Returns:
      new exception handler object

    • removeExceptionHandler

      public void removeExceptionHandler(CodeExceptionGen c)
      Remove an exception handler.

    • removeExceptionHandlers

      public void removeExceptionHandlers()
      Remove all line numbers.

    • getExceptionHandlers

      public CodeExceptionGen[] getExceptionHandlers()

    • addException

      public void addException(String className)
      Add an exception possibly thrown by this method.
      Parameters:
      className - (fully qualified) name of exception

    • removeException

      public void removeException(String c)
      Remove an exception.

    • removeExceptions

      public void removeExceptions()
      Remove all exceptions.

    • getExceptions

      public String[] getExceptions()

    • 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

    • removeLocalVariableTypeTable

      public void removeLocalVariableTypeTable()
      Remove the LocalVariableTypeTable

    • removeCodeAttribute

      public void removeCodeAttribute(Attribute a)
      Remove a code attribute.

    • removeCodeAttributes

      public void removeCodeAttributes()
      Remove all code attributes.

    • getCodeAttributes

      public Attribute[] getCodeAttributes()
      Returns:
      all attributes of this method.

    • addAnnotationsAsAttribute

      public void addAnnotationsAsAttribute(ConstantPoolGen cp)
      Since:
      6.0

    • addParameterAnnotationsAsAttribute

      public void addParameterAnnotationsAsAttribute(ConstantPoolGen cp)
      Since:
      6.0

    • removeRuntimeAttributes

      public void removeRuntimeAttributes(Attribute[] attrs)
      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

    • getMethod

      public Method getMethod()
      Get method object. Never forget to call setMaxStack() or setMaxStack(max), respectively, before calling this method (the same applies for max locals).
      Returns:
      method object

    • 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.

    • setMaxLocals

      public void setMaxLocals(int m)
      Set maximum number of local variables.

    • getMaxLocals

      public int getMaxLocals()

    • setMaxStack

      public void setMaxStack(int m)
      Set maximum stack size for this method.

    • getMaxStack

      public int getMaxStack()

    • getClassName

      public String getClassName()
      Returns:
      class that contains this method

    • setClassName

      public void setClassName(String class_name)

    • setReturnType

      public void setReturnType(Type return_type)

    • getReturnType

      public Type getReturnType()

    • setArgumentTypes

      public void setArgumentTypes(Type[] arg_types)

    • getArgumentTypes

      public Type[] getArgumentTypes()

    • setArgumentType

      public void setArgumentType(int i, Type type)

    • getArgumentType

      public Type getArgumentType(int i)

    • setArgumentNames

      public void setArgumentNames(String[] arg_names)

    • getArgumentNames

      public String[] getArgumentNames()

    • setArgumentName

      public void setArgumentName(int i, String name)

    • getArgumentName

      public String getArgumentName(int i)

    • getInstructionList

      public InstructionList getInstructionList()

    • setInstructionList

      public void setInstructionList(InstructionList il)

    • getSignature

      public String getSignature()
      Specified by:
      getSignature in class FieldGenOrMethodGen
      Returns:
      signature of method/field.

    • setMaxStack

      public void setMaxStack()
      Computes max. stack size by performing control flow analysis.

    • setMaxLocals

      public void setMaxLocals()
      Compute maximum number of local variables.

    • stripAttributes

      public void stripAttributes(boolean flag)
      Do not/Do produce attributes code attributesLineNumberTable and LocalVariableTable, like javac -O

    • 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

    • addObserver

      public void addObserver(MethodObserver o)
      Add observer for this object.

    • removeObserver

      public void removeObserver(MethodObserver o)
      Remove observer for this object.

    • 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 he has finished editing the object.

    • 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.

    • copy

      public MethodGen copy(String className, ConstantPoolGen cp)
      Returns:
      deep copy of this method

    • getAnnotationsOnParameter

      public List<AnnotationEntryGen> getAnnotationsOnParameter(int i)
      Return a list of AnnotationGen objects representing parameter annotations
      Since:
      6.0

    • addParameterAnnotation

      public void addParameterAnnotation(int parameterIndex, AnnotationEntryGen annotation)

    • getComparator

      public static BCELComparator getComparator()
      Returns:
      Comparison strategy object

    • setComparator

      public static void setComparator(BCELComparator comparator)
      Parameters:
      comparator - Comparison strategy object

    • 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:

    • hashCode

      public int hashCode()
      Return value as defined by given BCELComparator strategy. By default return the hashcode of the method's name XOR signature.
      Overrides:
      hashCode in class Object
      See Also: