resolve Parameterized Type - Java Reflection

Java examples for Reflection:Method Parameter

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Description

resolve Parameterized Type

Demo Code

/*//from w w  w.j a  v a2  s.c om
 * Copyright 2007-2011 Hidekatsu Izuno
 *
 * 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.
 */
//package com.java2s;

import java.lang.reflect.Array;

import java.lang.reflect.GenericArrayType;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.WildcardType;

public class Main {
    public static ParameterizedType resolveParameterizedType(Type t,
            Class<?> baseClass) {
        Class<?> raw = getRawType(t);

        if (t instanceof ParameterizedType
                && baseClass.isAssignableFrom(raw)) {
            return (ParameterizedType) t;
        }

        ParameterizedType pt = null;
        if (raw.getSuperclass() != null
                && raw.getSuperclass() != Object.class) {
            pt = resolveParameterizedType(raw.getGenericSuperclass(),
                    baseClass);
            if (pt != null)
                return pt;
        }
        if (!raw.isInterface()) {
            for (Type ifs : raw.getGenericInterfaces()) {
                pt = resolveParameterizedType(ifs, baseClass);
                if (pt != null)
                    return pt;
            }
        }
        return null;
    }

    public static Class<?> getRawType(Type t) {
        if (t instanceof Class<?>) {
            return (Class<?>) t;
        } else if (t instanceof ParameterizedType) {
            return (Class<?>) ((ParameterizedType) t).getRawType();
        } else if (t instanceof GenericArrayType) {
            Class<?> cls = null;
            try {
                cls = Array
                        .newInstance(
                                getRawType(((GenericArrayType) t)
                                        .getGenericComponentType()),
                                0).getClass();
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
            return cls;
        } else if (t instanceof WildcardType) {
            Type[] types = ((WildcardType) t).getUpperBounds();
            return (types.length > 0) ? getRawType(types[0]) : Object.class;
        } else {
            return Object.class;
        }
    }
}

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