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Java example source code file (Index.java)

This example Java source code file (Index.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

concurrenthashmap, illegalargumentexception, index, integer, map, object, override, serializable, string, stringbuilder, suppresswarnings, threading, threads, unable, util

The Index.java Java example source code

/*
 *
 *  * Copyright 2015 Skymind,Inc.
 *  *
 *  *    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 org.deeplearning4j.util;


import java.io.*;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

/**
 * An index is a transform of objects augmented with a list and a reverse lookup table
 * for fast lookups.
 * Indices are used for vocabulary in many of the natural language processing
 * @author Adam Gibson
 *
 */
@SuppressWarnings({"rawtypes","unchecked"})
public class Index implements Serializable {

    /**
     *
     */
    private static final long serialVersionUID = 1160629777026141078L;
    Map<Integer,Object> objects = new ConcurrentHashMap<>();

    Map<Object,Integer> indexes = new ConcurrentHashMap<>();

    public synchronized boolean add(Object o,int idx) {
        if(o instanceof String) {
            if(o.toString().isEmpty())
                throw new IllegalArgumentException("Unable to add the empty string");
        }

        Integer index = indexes.get(o);
        if (index == null) {
            index = idx;
            objects.put(idx,o);
            indexes.put(o, index);
            return true;
        }
        return false;
    }

    public synchronized boolean add(Object o) {
        if(o instanceof String) {
            if(o.toString().isEmpty())
                throw new IllegalArgumentException("Unable to add the empty string");
        }
        Integer index = indexes.get(o);
        if (index == null) {
            index = objects.size();
            objects.put(index,o);
            indexes.put(o, index);
            return true;
        }
        return false;
    }

    public synchronized int indexOf(Object o) {
        Integer index = indexes.get(o);
        if (index == null) { return -1; }
        else { return index; }
    }

    public synchronized Object get(int i) {
        return objects.get(i);
    }

    public int size() {
        return objects.size();
    }

    @Override
    public String toString() {
        StringBuilder buff = new StringBuilder("[");
        int sz = objects.size();
        int i;
        for (i = 0; i < sz; i++) {
            Object e = objects.get(i);
            buff.append(e);
            if (i < (sz-1)) buff.append(" , ");
        }
        buff.append("]");
        return buff.toString();

    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        Index index = (Index) o;

        if (objects != null ? !objects.equals(index.objects) : index.objects != null) return false;
        return !(indexes != null ? !indexes.equals(index.indexes) : index.indexes != null);

    }

    @Override
    public int hashCode() {
        int result = objects != null ? objects.hashCode() : 0;
        result = 31 * result + (indexes != null ? indexes.hashCode() : 0);
        return result;
    }
}

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