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Groovy example source code file (

This example Groovy source code file ( is included in the "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Groovy tags/keywords

class, class, classgeneratorexception, could, method, method, methodcaller, methodcaller, opcodes, reflection, string, string

The Groovy source code

 * Copyright 2003-2007 the original author or authors.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * See the License for the specific language governing permissions and
 * limitations under the License.
package org.codehaus.groovy.classgen.asm;

import java.lang.reflect.Method;

import org.codehaus.groovy.classgen.ClassGeneratorException;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;

 * A helper class to invoke methods more easily in ASM
 * @author <a href="">James Strachan
 * @version $Revision: 20965 $
public class MethodCaller implements Opcodes {

    private int opcode;
    private String internalName;
    private String name;
    private Class theClass;
    private String methodDescriptor;

    public static MethodCaller newStatic(Class theClass, String name) {
        return new MethodCaller(INVOKESTATIC, theClass, name);

    public static MethodCaller newInterface(Class theClass, String name) {
        return new MethodCaller(INVOKEINTERFACE, theClass, name);

    public static MethodCaller newVirtual(Class theClass, String name) {
        return new MethodCaller(INVOKEVIRTUAL, theClass, name);

    public MethodCaller(int opcode, Class theClass, String name) {
        this.opcode = opcode;
        this.internalName = Type.getInternalName(theClass);
        this.theClass = theClass; = name;


    public void call(MethodVisitor methodVisitor) {
        methodVisitor.visitMethodInsn(opcode, internalName, name, getMethodDescriptor());

    public String getMethodDescriptor() {
        if (methodDescriptor == null) {
            Method method = getMethod();
            methodDescriptor = Type.getMethodDescriptor(method);
        return methodDescriptor;

    protected Method getMethod() {
        Method[] methods = theClass.getMethods();
        for (int i = 0; i < methods.length; i++) {
            Method method = methods[i];
            if (method.getName().equals(name)) {
                return method;
        throw new ClassGeneratorException("Could not find method: " + name + " on class: " + theClass);

Other Groovy examples (source code examples)

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