Java Reflection Method Name getMethodNameAndDescriptor(Method m)

Description

Returns a string consisting of the given method's name followed by its "method descriptor", as appropriate for use in the computation of the "method hash".

License

Apache License

Declaration

public static String getMethodNameAndDescriptor(Method m) 

Method Source Code

//package com.java2s;
/*//from   w ww .  ja v  a2s  .co m
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.lang.reflect.Method;

public class Main {
    /**
     * Returns a string consisting of the given method's name followed by
     * its "method descriptor", as appropriate for use in the computation
     * of the "method hash".
     *
     * See section 4.3.3 of The Java(TM) Virtual Machine Specification for
     * the definition of a "method descriptor".
     */
    public static String getMethodNameAndDescriptor(Method m) {
        StringBuffer desc = new StringBuffer(m.getName());
        desc.append('(');
        Class[] paramTypes = m.getParameterTypes();
        for (int i = 0; i < paramTypes.length; i++) {
            desc.append(getTypeDescriptor(paramTypes[i]));
        }
        desc.append(')');
        Class returnType = m.getReturnType();
        if (returnType == void.class) { // optimization: handle void here
            desc.append('V');
        } else {
            desc.append(getTypeDescriptor(returnType));
        }
        return desc.toString();
    }

    /**
     * Returns the descriptor of a particular type, as appropriate for either
     * a parameter type or return type in a method descriptor.
     */
    private static String getTypeDescriptor(Class type) {
        if (type.isPrimitive()) {
            if (type == int.class) {
                return "I";
            } else if (type == boolean.class) {
                return "Z";
            } else if (type == byte.class) {
                return "B";
            } else if (type == char.class) {
                return "C";
            } else if (type == short.class) {
                return "S";
            } else if (type == long.class) {
                return "J";
            } else if (type == float.class) {
                return "F";
            } else if (type == double.class) {
                return "D";
            } else if (type == void.class) {
                return "V";
            } else {
                throw new Error("unrecognized primitive type: " + type);
            }
        } else if (type.isArray()) {
            /*
             * According to JLS 20.3.2, the getName() method on Class does
             * return the virtual machine type descriptor format for array
             * classes (only); using that should be quicker than the otherwise
             * obvious code:
             *
             *     return "[" + getTypeDescriptor(type.getComponentType());
             */
            return type.getName().replace('.', '/');
        } else {
            return "L" + type.getName().replace('.', '/') + ";";
        }
    }
}

Related

1. getMethodName(Method method)
2. getMethodName(Method method)
3. getMethodName(Method method)
4. getMethodName(Method method, boolean useSegment, String segment, String value)
5. getMethodName(String prefix, String fieldName)
6. getMethodNameList(Class theClass)
7. getMethodNameMinusGet(Method aMethod)
8. getMethodNames(Class cls, boolean insertDefaultValues)
9. getMethodNames(Class cls)