Java Reflection Field Find findField(Object target, Class type)

Description

find Field

License

Apache License

Declaration

public static <T> T findField(Object target, Class<T> type) 

Method Source Code

//package com.java2s;
/*//  w w  w.  j av a 2  s  . c om
 * Copyright 2010 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
 *
 *      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.Field;
import java.util.ArrayList;
import java.util.List;

public class Main {
    public static <T> T findField(Object target, Class<T> type) {
        List<T> matches = new ArrayList<T>();
        for (Class<?> cl = target.getClass(); cl != Object.class; cl = cl.getSuperclass()) {
            for (Field field : cl.getDeclaredFields()) {
                if (type.isAssignableFrom(field.getType())) {
                    field.setAccessible(true);
                    try {
                        matches.add(type.cast(field.get(target)));
                    } catch (IllegalAccessException e) {
                        throw new RuntimeException(e);
                    }
                }
            }
        }
        if (matches.isEmpty()) {
            return null;
        }
        if (matches.size() > 1) {
            throw new RuntimeException(String.format("Multiple %s fields found for test class %s.",
                    type.getSimpleName(), target.getClass().getSimpleName()));
        }
        return matches.get(0);
    }
}

Related

1. findField(Object obj, String fieldName, Class type)
2. findField(Object obj, String name)
3. findField(Object object, String fieldName)
4. findField(Object object, String name, Class klass)
5. findField(Object propertyId, Class classOfItem)
6. findField(Object target, String fieldName)
7. findField(String fieldName, ArrayList fields)
8. findField(String fieldName, Class cl)
9. findField(String fieldName, Class type)