Main.java Source code

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Here is the source code for Main.java

Source

//package com.java2s;
/*
 * Copyright 1999-2004 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.
 */

import java.util.Collection;
import java.util.Enumeration;

import java.util.Iterator;
import java.util.List;

import java.util.Map;

public class Main {
    /**
     * Given an Object, and an index, it will get the nth value in the object.
     * <ul>
     * <li>If obj is a Map, get the nth value from the <b>key</b> iterator.
     * <li>If obj is a List or an array, get the nth value.
     * <li>If obj is an iterator, enumeration or Collection, get the nth value
     * from the iterator.
     * <li>Return the original obj.
     * </ul>
     * 
     * @param obj
     *            the object to get an index of
     * @param index
     *            the index to get
     * @throws IndexOutOfBoundsException
     * @throws NoSuchElementException
     */
    public static Object index(Object obj, int idx) {
        return index(obj, new Integer(idx));
    }

    /**
     * Given an Object, and a key (index), it will get value associated with
     * that key in the Object. The following checks are made:
     * <ul>
     * <li>If obj is a Map, use the index as a key to get a value. If no match
     * continue.
     * <li>Check key is an Integer. If not, return the object passed in.
     * <li>If obj is a Map, get the nth value from the <b>key</b> iterator.
     * <li>If obj is a List or an array, get the nth value.
     * <li>If obj is an iterator, enumeration or Collection, get the nth value
     * from the iterator.
     * <li>Return the original obj.
     * </ul>
     * 
     * @param obj
     *            the object to get an index of
     * @param index
     *            the index to get
     * @return the object at the specified index
     * @throws IndexOutOfBoundsException
     * @throws NoSuchElementException
     */
    public static Object index(Object obj, Object index) {
        if (obj instanceof Map) {
            Map map = (Map) obj;
            if (map.containsKey(index)) {
                return map.get(index);
            }
        }
        int idx = -1;
        if (index instanceof Integer) {
            idx = ((Integer) index).intValue();
        }
        if (idx < 0) {
            return obj;
        } else if (obj instanceof Map) {
            Map map = (Map) obj;
            Iterator iterator = map.keySet().iterator();
            return index(iterator, idx);
        } else if (obj instanceof List) {
            return ((List) obj).get(idx);
        } else if (obj instanceof Object[]) {
            return ((Object[]) obj)[idx];
        } else if (obj instanceof Enumeration) {
            Enumeration enumeration = (Enumeration) obj;
            while (enumeration.hasMoreElements()) {
                idx--;
                if (idx == -1) {
                    return enumeration.nextElement();
                } else {
                    enumeration.nextElement();
                }
            }
        } else if (obj instanceof Iterator) {
            return index((Iterator) obj, idx);
        } else if (obj instanceof Collection) {
            Iterator iterator = ((Collection) obj).iterator();
            return index(iterator, idx);
        }
        return obj;
    }

    private static Object index(Iterator iterator, int idx) {
        while (iterator.hasNext()) {
            idx--;
            if (idx == -1) {
                return iterator.next();
            } else {
                iterator.next();
            }
        }
        return iterator;
    }
}