一些常用类:Random、BigInteger、BigDecimal、DecimalFormat
常用类:
格式化人民币:
基于随机数类Random的三色球摇奖Demo:
package randomdemo; import java.util.Arrays; import java.util.Random; /* * 随机数实现双色球demo */ public class RandomDemo { public static void main(String[] args) { //球池 int[] ballpool = new int[33]; for(int i=0; i< ballpool.length ; i++){ ballpool[i] = i+1; } //创建红球奖池 int[] redResult = new int[6]; int length = 0; //标记池,默认为false boolean[] isUsed = new boolean[33]; Random rd = new Random(); //生成红球奖池 while(true){ int red = rd.nextInt(33); //去重 if(isUsed[red]==true){ continue; } //将选中的红球放入结果中,然后数组长度自增 redResult[length++] = ballpool[red]; //循环出口 if(length == 6) break; //去重 isUsed[red] = true; } //将数组排序 Arrays.sort(redResult); //篮球奖池 int blueResult = rd.nextInt(16); System.out.println("红球奖池:"); for(int i : redResult){ System.out.print(i+" "); } System.out.println("\n蓝球奖池: \n"+blueResult); } }