Java Reflection Generic Type from Field getGenericClasses(Field field)

Description

get Generic Classes

License

Open Source License

Parameter

Parameter	Description
field	is the field to return the generics from

Return

the generics assigned to a specific field or a empty list

Declaration

public static Class<?>[] getGenericClasses(Field field) 

Method Source Code

//package com.java2s;
/*/*w ww  . jav a 2  s .  c  o  m*/
 * The MIT License (MIT)
 *
 * Copyright (c) 2015 Ziver Koc
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

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

public class Main {
    /**
     * @param   field       is the field to return the generics from
     * @return the generics assigned to a specific field or a empty list
     */
    public static Class<?>[] getGenericClasses(Field field) {
        return getGenericClasses(field.getGenericType());
    }

    /**
     * Traverses the class hierarchy and searches for the given super class or interface
     * and returns the assigned generic types.
     *
     * @param   c               the source class
     * @param   superClass      is the super class to search for
     * @return the generics for a specific super class or a empty list if
     *         there is no generics or the super class is not found
     */
    public static Class<?>[] getGenericClasses(Class<?> c, Class<?> superClass) {
        if (superClass != null) {
            // Search for the super class
            while (c.getSuperclass() != null && c.getSuperclass() != Object.class) {
                // Did we find the super class?
                if (superClass.isAssignableFrom(c.getSuperclass()))
                    return getGenericClasses(c.getGenericSuperclass());
                c = c.getSuperclass();
            }
        }
        return new Class[0];
    }

    private static Class<?>[] getGenericClasses(Type genericType) {
        if (genericType instanceof ParameterizedType) {
            ParameterizedType aType = (ParameterizedType) genericType;
            Type[] argTypes = aType.getActualTypeArguments();
            Class<?>[] classArray = new Class<?>[argTypes.length];
            for (int i = 0; i < classArray.length; ++i) {
                if (argTypes[i] instanceof Class)
                    classArray[i] = (Class<?>) argTypes[i];
            }
            return classArray;
        }
        return new Class[0];
    }
}

Related

1. getGenericArgument(Field field, int index)
2. getGenericClass(Field f, int n)
3. getGenericElementType(Field field)
4. getGenericFieldClassType(Class clz, String propertyName)
5. getGenericFieldType(Field field, boolean isAllowNull)
6. getGenericFieldType(Object target, String fieldName)