GetFieldList.java

/***************************************************************************
   Copyright 2013 Emily Estes

   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 net.metanotion.util.reflect;


import java.lang.reflect.Field;
import net.metanotion.util.Dictionary;

/** Traverse a sequence of fields from a parent object through the references
and return the value of the final field. Basically it looks up pointer chases like
"foo.bar.baz".
*/
public final class GetFieldList implements Dictionary {
    private final Field[] fields;

    /** Create a new instance that looks up the result of a dereference sequence.
        @param f The sequence of fields to dereferenece.
    */
    public GetFieldList(Field[] f) { this.fields = f; }

    @Override public Object get(Object instance) {
        try {
            for(Field f: fields) { instance = f.get(instance); }
            return instance;
        } catch (IllegalAccessException iae) { throw new RuntimeException(iae); }
    }
}