Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
/**
 * Copyright (C) 2012 Philip W. Sorst <philip@sorst.net>
 * and individual contributors as indicated
 * by the @authors tag.
 *
 * 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.Iterator;

public class Main {
    public static <V> V getRandom(Collection<V> collection) {

        if (collection.isEmpty()) {
            return null;
        }

        int randIdx = (int) Math.round(Math.random() * (collection.size() - 1));
        int count = 0;
        Iterator<V> iterator = collection.iterator();
        while (iterator.hasNext()) {
            V current = iterator.next();
            if (count == randIdx) {
                return current;
            }
            count++;
        }

        throw new RuntimeException("Shouldn't happen");
    }

    /**
     * Nullsafe check if a collection is empty.
     * 
     * @param obj
     *            Null or a subclass of Collection.
     * @throws IllegalArgumentException
     *             Thrown if obj is not null and not an instance of Collection.
     */
    public static boolean isEmpty(Object obj) {

        if (obj == null) {
            return true;
        }

        if (obj instanceof Collection) {
            return ((Collection<?>) obj).isEmpty();
        }

        throw new IllegalArgumentException("Given Object was not a collection");
    }
}