Main.java Source code

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Here is the source code for Main.java

Source

//package com.java2s;
import java.lang.reflect.Array;

import java.util.Collection;

import java.util.Enumeration;

import java.util.Iterator;

import java.util.Map;

public class Main {
    /**
     * Checks if the specified collection/array/iterator is empty.
     * <p>
     * This method can handles objects as follows
     * <ul>
     * <li>Collection - via collection isEmpty
     * <li>Map - via map isEmpty
     * <li>Array - using array size
     * <li>Iterator - via hasNext
     * <li>Enumeration - via hasMoreElements
     * </ul>
     * <p>
     * Note: This method is named to avoid clashing with
     * {@link #isEmpty(Collection)}.
     * 
     * @param object
     *            the object to get the size of, not null
     * @return true if empty
     * @throws IllegalArgumentException
     *             thrown if object is not recognised or null
     */
    public static boolean sizeIsEmpty(Object object) {
        if (object instanceof Collection) {
            return ((Collection<?>) object).isEmpty();
        } else if (object instanceof Map) {
            return ((Map<?, ?>) object).isEmpty();
        } else if (object instanceof Object[]) {
            return ((Object[]) object).length == 0;
        } else if (object instanceof Iterator) {
            return !((Iterator<?>) object).hasNext();
        } else if (object instanceof Enumeration) {
            return !((Enumeration<?>) object).hasMoreElements();
        } else if (object == null) {
            throw new IllegalArgumentException("Unsupported object type: null");
        } else {
            try {
                return Array.getLength(object) == 0;
            } catch (IllegalArgumentException ex) {
                throw new IllegalArgumentException("Unsupported object type: " + object.getClass().getName());
            }
        }
    }

    public static boolean isEmpty(Map<?, ?> map) {
        return (map == null) || (map.size() == 0);
    }

    public static boolean isEmpty(Collection<?> collection) {
        return (collection == null) || (collection.size() == 0);
    }

    /**
     * Gets the size of the collection/iterator specified.
     * <p>
     * This method can handles objects as follows
     * <ul>
     * <li>Collection - the collection size
     * <li>Map - the map size
     * <li>Array - the array size
     * <li>Iterator - the number of elements remaining in the iterator
     * <li>Enumeration - the number of elements remaining in the enumeration
     * </ul>
     * 
     * @param object
     *            the object to get the size of
     * @return the size of the specified collection
     * @throws IllegalArgumentException
     *             thrown if object is not recognised or null
     * @since Commons Collections 3.1
     */
    public static int size(Object object) {
        int total = 0;
        if (object instanceof Map) {
            total = ((Map<?, ?>) object).size();
        } else if (object instanceof Collection) {
            total = ((Collection<?>) object).size();
        } else if (object instanceof Object[]) {
            total = ((Object[]) object).length;
        } else if (object instanceof Iterator) {
            Iterator<?> it = (Iterator<?>) object;
            while (it.hasNext()) {
                total++;
                it.next();
            }
        } else if (object instanceof Enumeration) {
            Enumeration<?> it = (Enumeration<?>) object;
            while (it.hasMoreElements()) {
                total++;
                it.nextElement();
            }
        } else if (object == null) {
            throw new IllegalArgumentException("Unsupported object type: null");
        } else {
            try {
                total = Array.getLength(object);
            } catch (IllegalArgumentException ex) {
                throw new IllegalArgumentException("Unsupported object type: " + object.getClass().getName());
            }
        }
        return total;
    }
}