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Java example source code file (SymbolHash.java)

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

Learn more about this Java project at its project page.

Java - Java tags/keywords

entry, object, symbolhash

The SymbolHash.java Java example source code

/*
 * reserved comment block
 * DO NOT REMOVE OR ALTER!
 */
/*
 * Copyright 2001, 2002,2004 The Apache Software Foundation.
 *
 * 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 com.sun.org.apache.xerces.internal.util;


/**
 * This class is an unsynchronized hash table primary used for String
 * to Object mapping.
 * <p>
 * The hash code uses the same algorithm as SymbolTable class.
 *
 * @author Elena Litani
 * @version $Id: SymbolHash.java,v 1.7 2010-11-01 04:40:14 joehw Exp $
 */
public class SymbolHash {

    //
    // Constants
    //

    /** Default table size. */
    protected int fTableSize = 101;

    //
    // Data
    //

    /** Buckets. */
    protected Entry[] fBuckets;

    /** Number of elements. */
    protected int fNum = 0;

    //
    // Constructors
    //

    /** Constructs a key table with the default size. */
    public SymbolHash() {
        fBuckets = new Entry[fTableSize];
    }

    /**
     * Constructs a key table with a given size.
     *
     * @param size  the size of the key table.
     */
    public SymbolHash(int size) {
        fTableSize = size;
        fBuckets = new Entry[fTableSize];
    }

    //
    // Public methods
    //

    /**
     * Adds the key/value mapping to the key table. If the key already exists,
     * the previous value associated with this key is overwritten by the new
     * value.
     *
     * @param key
     * @param value
     */
    public void put(Object key, Object value) {
        int bucket = (key.hashCode() & 0x7FFFFFFF) % fTableSize;
        Entry entry = search(key, bucket);

        // replace old value
        if (entry != null) {
            entry.value = value;
        }
        // create new entry
        else {
            entry = new Entry(key, value, fBuckets[bucket]);
            fBuckets[bucket] = entry;
            fNum++;
        }
    }

    /**
     * Get the value associated with the given key.
     *
     * @param key
     * @return the value associated with the given key.
     */
    public Object get(Object key) {
        int bucket = (key.hashCode() & 0x7FFFFFFF) % fTableSize;
        Entry entry = search(key, bucket);
        if (entry != null) {
            return entry.value;
        }
        return null;
    }

    /**
     * Get the number of key/value pairs stored in this table.
     *
     * @return the number of key/value pairs stored in this table.
     */
    public int getLength() {
        return fNum;
    }

    /**
     * Add all values to the given array. The array must have enough entry.
     *
     * @param elements  the array to store the elements
     * @param from      where to start store element in the array
     * @return          number of elements copied to the array
     */
    public int getValues(Object[] elements, int from) {
        for (int i=0, j=0; i<fTableSize && j

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