Java Reflection Generic Parameter getGenericParameter(final Type type, final int index)

Description

get Generic Parameter

License

Apache License

Declaration

public static Type getGenericParameter(final Type type, final int index) 

Method Source Code

//package com.java2s;
/*//  w  w w.  j a  v a 2s  .  c o m
 * Copyright 2004-2012 the Seasar Foundation and the Others.
 *
 * 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
 *
 *     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.*;

public class Main {

    public static Type getGenericParameter(final Type type, final int index) {
        if (!(type instanceof ParameterizedType)) {
            return null;
        }
        final Type[] genericParameter = getGenericParameters(type);
        if (genericParameter == null) {
            return null;
        }
        return genericParameter[index];
    }

    public static Type[] getGenericParameters(final Type type) {
        if (type instanceof ParameterizedType) {
            return ParameterizedType.class.cast(type).getActualTypeArguments();
        }
        if (type instanceof GenericArrayType) {
            return getGenericParameters(GenericArrayType.class.cast(type).getGenericComponentType());
        }
        return null;
    }
}

Related

1. getGeneric(ParameterizedType type)
2. getGenericParameter(final Type type)
3. getGenericParameterList(Type type)
4. getGenericParameters(final Type type)
5. getGenericParameterType(Method method, int paramIdx)
6. getGenericParameterType(Type type, int index)