Java Reflection Field Find findField(Class clazz, String fieldName)

Description

find Field

License

Open Source License

Declaration

public static Field findField(Class clazz, String fieldName) 

Method Source Code

//package com.java2s;
/**/*from   w  w  w  .j  a v a 2 s. co  m*/
 * Copyright 2010 Google Inc.
    
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
    
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
    
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 **/

import java.lang.reflect.*;
import java.util.*;

public class Main {
    public static Field findField(Class clazz, String fieldName) {
        Vector<Field> fields = new Vector<Field>();
        getField(fields, clazz, fieldName);
        if (fields.size() == 0) {
            throw new RuntimeException(
                    "ClassHelper.findField: Could not find Field with name for given Class -- ClassName: "
                            + clazz.getName() + " -- FieldName: " + fieldName);
        }
        if (fields.size() != 1) {
            throw new RuntimeException(
                    "ClassHelper.findField: Could not find Field with name for given Class -- ClassName: "
                            + clazz.getClass().getName() + " -- FieldName: " + fieldName);
        }
        return (fields.get(0));
    }

    private static void getField(Vector<Field> inVector, Class clazz, String fieldName) {
        if (clazz == null) {
            return;
        }
        getField(inVector, clazz.getSuperclass(), fieldName);
        Field[] classFields = clazz.getDeclaredFields();
        for (Field field : classFields) {
            if (!(field.getName().equals(fieldName) && isStaticFinal(field))) {
                continue;
            }
            field.setAccessible(true);
            inVector.add(field);
        }
    }

    /**
     * Get the underlying class for a type, or null if the type is a variable
     * type.
     *
     * @param type the type
     * @return the underlying class
     */
    public static Class<?> getClass(Type type) {
        if (type instanceof Class) {
            return (Class) type;
        } else if (type instanceof ParameterizedType) {
            return getClass(((ParameterizedType) type).getRawType());
        } else if (type instanceof GenericArrayType) {
            Type componentType = ((GenericArrayType) type).getGenericComponentType();
            Class<?> componentClass = getClass(componentType);
            if (componentClass != null) {
                return Array.newInstance(componentClass, 0).getClass();
            } else {
                return null;
            }
        } else {
            return null;
        }
    }

    private static boolean isStaticFinal(Field f) {
        int mods = f.getModifiers();
        return Modifier.isStatic(mods) || Modifier.isFinal(mods);
    }
}

Related

1. findField(Class c, Class fieldtype)
2. findField(Class c, String fieldName)
3. findField(Class classBeFind, String name)
4. findField(Class classType, String fieldName, Class fieldType)
5. findField(Class clazz, Class type, String name)
6. findField(Class clazz, String fieldName)
7. findField(Class clazz, String name)
8. findField(Class clazz, String name)
9. findField(Class clazz, String name)