转载一篇java随机数生成，以备自用

该方法的作用是生成一个随机的int值，该值介于[0,n)的区间，也就是0到n之间的随机int值，包含0而不包含n。

直接上代码：

复制代码
package org.xiaowu.random.demo;

import java.util.Random;

import org.junit.Test;

public class RandomDemo {

@Test
public void Demo(){
    Random rnd = new Random();
    int code = rnd.nextInt(8999) + 1000;
    System.out.println("code:"+code);
}


@Test
public void Demo1(){
    Random r = new Random();
    int nextInt = r.nextInt();
    Random r1 = new Random(10);
    int nextInt2 = r1.nextInt();
    System.out.println("nextInt:"+nextInt);
    System.out.println("nextInt2:"+nextInt2);
}


/**
 * 生成[0,1.0)区间的小数
 * 
 */
@Test
public void Demo2(){
    Random r = new Random();
    double d1 = r.nextDouble();
    System.out.println("d1:"+d1);
}


/**
 * 生成[0,5.0)区间的小数
 * 
 */
@Test
public void Demo3(){
    Random r = new Random();
    double d2 = r.nextDouble()* 5;
    System.out.println("d1:"+d2);
}


/**
 * 生成[1,2.5)区间的小数
 * 
 */
@Test
public void Demo4(){
    Random r = new Random();
    double d3 = r.nextDouble() * 1.5 + 1;
    System.out.println("d1:"+d3);
}


/**
 * 生成任意整数
 * 
 */
@Test
public void Demo5(){
    Random r = new Random();
    int n1 = r.nextInt();
    System.out.println("d1:"+n1);
}



/**
 * 生成[0,10)区间的整数
 * 
 */
@Test
public void Demo6(){
    Random r = new Random();
    int n2 = r.nextInt(10);
    int n3 = Math.abs(r.nextInt() % 10);
    System.out.println("n2:"+n2);
    System.out.println("n3:"+n3);
}



/**
 * 生成[0,10]区间的整数
 * 
 */
@Test
public void Demo7(){
    Random r = new Random();
    int n3 = r.nextInt(11);
    int n4 = Math.abs(r.nextInt() % 11);
    System.out.println("n3:"+n3);
    System.out.println("n4:"+n4);
}


/**
 * 生成[-3,15)区间的整数
 * 
 */
@Test
public void Demo8(){
    Random r = new Random();
    int n4 = r.nextInt(18) - 3;
    int n5 = Math.abs(r.nextInt() % 18) - 3;
    System.out.println("n4:"+n4);
    System.out.println("n5:"+n5);
}

}
原连接：https://www.cnblogs.com/mr-wuxiansheng/p/6891693.html