home | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Commons Collections example source code file (TestBinaryHeap.java)

This example Commons Collections source code file (TestBinaryHeap.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 - Commons Collections tags/keywords

arraylist, binaryheap, binaryheap, collection, integer, integer, nosuchelementexception, nosuchelementexception, object, object, parent, random, stringbuffer, testbinaryheap, util

The Commons Collections TestBinaryHeap.java source code

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You 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 org.apache.commons.collections;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Comparator;
import java.util.NoSuchElementException;
import java.util.Random;

import junit.framework.Test;
import junit.framework.TestSuite;

import org.apache.commons.collections.collection.AbstractTestCollection;
import org.apache.commons.collections.comparators.ComparableComparator;
import org.apache.commons.collections.comparators.ReverseComparator;

/**
 * Tests the BinaryHeap.
 * 
 * @version $Revision: 646780 $ $Date: 2008-04-10 13:48:07 +0100 (Thu, 10 Apr 2008) $
 * 
 * @author Michael A. Smith
 */
public class TestBinaryHeap extends AbstractTestCollection {

    public static Test suite() {
        return new TestSuite(TestBinaryHeap.class);
    }

    public TestBinaryHeap(String testName) {
        super(testName);
    }

    //-----------------------------------------------------------------------  
    public void verify() {
        super.verify();
        BinaryHeap heap = (BinaryHeap) collection;

        Comparator c = heap.m_comparator;
        if (c == null)
            c = ComparatorUtils.naturalComparator();
        if (!heap.m_isMinHeap)
            c = ComparatorUtils.reversedComparator(c);

        Object[] tree = heap.m_elements;
        for (int i = 1; i <= heap.m_size; i++) {
            Object parent = tree[i];
            if (i * 2 <= heap.m_size) {
                assertTrue("Parent is less than or equal to its left child", c.compare(parent, tree[i * 2]) <= 0);
            }
            if (i * 2 + 1 < heap.m_size) {
                assertTrue("Parent is less than or equal to its right child", c.compare(parent, tree[i * 2 + 1]) <= 0);
            }
        }
    }

    //-----------------------------------------------------------------------  
    /**
     * Overridden because UnboundedFifoBuffer isn't fail fast.
     * @return false
     */
    public boolean isFailFastSupported() {
        return false;
    }

    //-----------------------------------------------------------------------  
    public Collection makeConfirmedCollection() {
        return new ArrayList();
    }

    public Collection makeConfirmedFullCollection() {
        ArrayList list = new ArrayList();
        list.addAll(Arrays.asList(getFullElements()));
        return list;
    }

    /**
     * Return a new, empty {@link Object} to used for testing.
     */
    public Collection makeCollection() {
        return new BinaryHeap();
    }

    //-----------------------------------------------------------------------  
    public Object[] getFullElements() {
        return getFullNonNullStringElements();
    }

    public Object[] getOtherElements() {
        return getOtherNonNullStringElements();
    }

    //-----------------------------------------------------------------------  
    public void testBasicOps() {
        BinaryHeap heap = new BinaryHeap();

        assertTrue("heap should be empty after create", heap.isEmpty());

        try {
            heap.peek();
            fail("NoSuchElementException should be thrown if peek is called before any elements are inserted");
        } catch (NoSuchElementException e) {
            // expected
        }

        try {
            heap.pop();
            fail("NoSuchElementException should be thrown if pop is called before any elements are inserted");
        } catch (NoSuchElementException e) {
            // expected
        }

        heap.insert("a");
        heap.insert("c");
        heap.insert("e");
        heap.insert("b");
        heap.insert("d");
        heap.insert("n");
        heap.insert("m");
        heap.insert("l");
        heap.insert("k");
        heap.insert("j");
        heap.insert("i");
        heap.insert("h");
        heap.insert("g");
        heap.insert("f");

        assertTrue("heap should not be empty after inserts", !heap.isEmpty());

        for (int i = 0; i < 14; i++) {
            assertEquals(
                "peek using default constructor should return minimum value in the binary heap",
                String.valueOf((char) ('a' + i)),
                heap.peek());

            assertEquals(
                "pop using default constructor should return minimum value in the binary heap",
                String.valueOf((char) ('a' + i)),
                heap.pop());

            if (i + 1 < 14) {
                assertTrue("heap should not be empty before all elements are popped", !heap.isEmpty());
            } else {
                assertTrue("heap should be empty after all elements are popped", heap.isEmpty());
            }
        }

        try {
            heap.peek();
            fail("NoSuchElementException should be thrown if peek is called after all elements are popped");
        } catch (NoSuchElementException e) {
            // expected
        }

        try {
            heap.pop();
            fail("NoSuchElementException should be thrown if pop is called after all elements are popped");
        } catch (NoSuchElementException e) {
            // expected
        }
    }

    public void testBasicComparatorOps() {
        BinaryHeap heap = new BinaryHeap(new ReverseComparator(new ComparableComparator()));

        assertTrue("heap should be empty after create", heap.isEmpty());

        try {
            heap.peek();
            fail("NoSuchElementException should be thrown if peek is called before any elements are inserted");
        } catch (NoSuchElementException e) {
            // expected
        }

        try {
            heap.pop();
            fail("NoSuchElementException should be thrown if pop is called before any elements are inserted");
        } catch (NoSuchElementException e) {
            // expected
        }

        heap.insert("a");
        heap.insert("c");
        heap.insert("e");
        heap.insert("b");
        heap.insert("d");
        heap.insert("n");
        heap.insert("m");
        heap.insert("l");
        heap.insert("k");
        heap.insert("j");
        heap.insert("i");
        heap.insert("h");
        heap.insert("g");
        heap.insert("f");

        assertTrue("heap should not be empty after inserts", !heap.isEmpty());

        for (int i = 0; i < 14; i++) {

            // note: since we're using a comparator that reverses items, the
            // "minimum" item is "n", and the "maximum" item is "a".

            assertEquals(
                "peek using default constructor should return minimum value in the binary heap",
                String.valueOf((char) ('n' - i)),
                heap.peek());

            assertEquals(
                "pop using default constructor should return minimum value in the binary heap",
                String.valueOf((char) ('n' - i)),
                heap.pop());

            if (i + 1 < 14) {
                assertTrue("heap should not be empty before all elements are popped", !heap.isEmpty());
            } else {
                assertTrue("heap should be empty after all elements are popped", heap.isEmpty());
            }
        }

        try {
            heap.peek();
            fail("NoSuchElementException should be thrown if peek is called after all elements are popped");
        } catch (NoSuchElementException e) {
            // expected
        }

        try {
            heap.pop();
            fail("NoSuchElementException should be thrown if pop is called after all elements are popped");
        } catch (NoSuchElementException e) {
            // expected
        }
    }
    
    /**
     * Illustrates bad internal heap state reported in Bugzilla PR #235818. 
     */  
    public void testAddRemove() {
        resetEmpty();
        BinaryHeap heap = (BinaryHeap) collection;
        heap.add(new Integer(0));
        heap.add(new Integer(2));
        heap.add(new Integer(4));
        heap.add(new Integer(3));
        heap.add(new Integer(8));
        heap.add(new Integer(10));
        heap.add(new Integer(12));
        heap.add(new Integer(3));
        confirmed.addAll(heap);
        // System.out.println(heap);
        Object obj = new Integer(10);
        heap.remove(obj);
        confirmed.remove(obj);
        // System.out.println(heap);
        verify();
    }
    
    /**
     * Generate heaps staring with Integers from 0 - heapSize - 1.
     * Then perform random add / remove operations, checking
     * heap order after modifications. Alternates minHeaps, maxHeaps.
     *
     * Based on code provided by Steve Phelps in PR #25818
     *
     */
    public void testRandom() {
        int iterations = 500;
        int heapSize = 100;
        int operations = 20;
        Random randGenerator = new Random();
        BinaryHeap h = null;
        for(int i=0; i < iterations; i++) {
            if (i < iterations / 2) {          
                h = new BinaryHeap(true);
            } else {
                h = new BinaryHeap(false);
            }
            for(int r = 0; r < heapSize; r++) {
                h.add( new Integer( randGenerator.nextInt(heapSize)) );
            }
            for( int r = 0; r < operations; r++ ) {
                h.remove(new Integer(r));
                h.add(new Integer(randGenerator.nextInt(heapSize)));
            }
            checkOrder(h);
        }
    }
     
    /**
     * Pops all elements from the heap and verifies that the elements come off
     * in the correct order.  NOTE: this method empties the heap.
     */
    protected void checkOrder(BinaryHeap h) {
        Integer lastNum = null;
        Integer num = null;
        boolean fail = false;
        while (!h.isEmpty()) {
            num = (Integer) h.pop();
            if (h.m_isMinHeap) {
                assertTrue(lastNum == null || num.intValue() >= lastNum.intValue());
            } else { // max heap
                assertTrue(lastNum == null || num.intValue() <= lastNum.intValue());
            }
            lastNum = num;
            num = null;
        }
    }
    
    /**
     * Returns a string showing the contents of the heap formatted as a tree.
     * Makes no attempt at padding levels or handling wrapping. 
     */
    protected String showTree(BinaryHeap h) {
        int count = 1;
        StringBuffer buffer = new StringBuffer();
        for (int offset = 1; count < h.size() + 1; offset *= 2) {
            for (int i = offset; i < offset * 2; i++) {
                if (i < h.m_elements.length && h.m_elements[i] != null) 
                    buffer.append(h.m_elements[i] + " ");
                count++;
            }
            buffer.append('\n');
        }
        return buffer.toString();
    }

}

Other Commons Collections examples (source code examples)

Here is a short list of links related to this Commons Collections TestBinaryHeap.java source code file:

new blog posts

 

Copyright 1998-2016 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.