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Groovy example source code file (OrderBy.java)

This example Groovy source code file (OrderBy.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Groovy tags/keywords

arraylist, closure, comparable, comparable, comparator, list, numberawarecomparator, numberawarecomparator, object, object, orderby, orderby, t, util

The Groovy OrderBy.java source code

/*
 * Copyright 2003-2010 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.
 */
package groovy.util;

import groovy.lang.Closure;
import org.codehaus.groovy.runtime.NumberAwareComparator;
import org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation;

import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;

/**
 * A helper class for sorting objects via a closure to return the field
 * or operation on which to sort.
 * 
 * @author <a href="mailto:james@coredevelopers.net">James Strachan
 * @version $Revision: 20330 $
 */
public class OrderBy<T> implements Comparator {

    private final List<Closure> closures;
    private boolean equalityCheck;
    private final NumberAwareComparator<Object> numberAwareComparator = new NumberAwareComparator();

    public OrderBy() {
        this.closures = new ArrayList<Closure>();
    }

    public OrderBy(Closure closure) {
        this();
        closures.add(closure);
    }

    public OrderBy(List<Closure> closures) {
        this.closures = closures;
    }

    public void add(Closure closure) {
        closures.add(closure);
    }

    public int compare(T object1, T object2) {
        for (Closure closure : closures) {
            Object value1 = closure.call(object1);
            Object value2 = closure.call(object2);
            int result;
            if (!equalityCheck || (value1 instanceof Comparable && value2 instanceof Comparable)) {
                result = numberAwareComparator.compare(value1, value2);
            } else {
                result = DefaultTypeTransformation.compareEqual(value1, value2) ? 0 : -1;
            }
            if (result == 0) continue;
            return result;
        }
        return 0;
    }

    public boolean isEqualityCheck() {
        return equalityCheck;
    }

    public void setEqualityCheck(boolean equalityCheck) {
        this.equalityCheck = equalityCheck;
    }
}

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