Java 取随机数的两种方法

用 java 编写程序时，取随机数通常有两种方法，1. 采用 Ramdom()， 2. 采用 Math.random(), 其实这两种方式基本差不多，写一个简单的例子，从一个list 中随机抽取一个记录.

方法一， 采用 Ramdom()

package test;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public class RandomTest {
	
	private Random random = new Random();
	 
	public static void main(String[] args) {
 
		List list = new ArrayList();
		list.add("Apple");
		list.add("Boy");
		list.add("Cat");
		list.add("Dog");
		list.add("Elephant");
 
		RandomTest obj = new RandomTest();
		for(int i = 0; i < 10; i++){
			System.out.println(obj.getRandomList(list));
		}
 
	}
 
	public String getRandomList(List list) {
 
	    //0-4
	    int index = random.nextInt(list.size());
	    System.out.println("\nIndex :" + index );
	    return list.get(index);
 
	}
 

}

public class MathRandomExample {
 
	public static void main(String[] args) {
 
		List list = new ArrayList();
		list.add(10);
		list.add(20);
		list.add(30);
		list.add(40);
		list.add(50);
 
		MathRandomExample obj = new MathRandomExample();
		for(int i = 0; i < 10; i++){
			System.out.println(obj.getRandomList(list));
		}
 
	}
 
	public int getRandomList(List list) {
 
	    //Math.random() = greater than or equal to 0.0 and less than 1
            //0-4
	    int index = (int)(Math.random()*list.size());
	    System.out.println("\nIndex :" + index );
	    return list.get(index);
 
	}
 
}