package com.web;
import java.util.Random;
import java.util.Scanner;
public class Test32 {
public static void main(String[] args) {
inputMethod();
System.out.println("================================");
guessMethod();
System.out.println("================================");
inputMethod2();//不写break时case的穿透现象
}
private static void inputMethod2() {
//故意不写break,输出如下
//case5
//case10
//default
int i = 5;
switch (i) {
case 0:
System.out.println("case0");
break;
case 5:
System.out.println("case5");
case 10:
System.out.println("case10");
default:
System.out.println("default");
}
}
private static void guessMethod() {
// 系统产生一个随机数1-100之间的。
//public int nextInt(int n):返回一个伪随机数,范围在0(包括)和指定值n(不包括)之间的int值。
Random r = new Random();
int randomNumber = r.nextInt(100) + 1;//写到while里会每次猜数字前都会生成不同的数字,最开始随机数要定下来
System.out.println("randomNumber = " + randomNumber);
try {
while (true) {
Scanner scanner = new Scanner(System.in);
System.out.print("Input number form 1 to 100:");
int guessNumber = scanner.nextInt();
if (guessNumber > randomNumber) {
System.out.println("too Big");
} else if (guessNumber < randomNumber) {
System.out.println("too small");
} else if (guessNumber == randomNumber) {
System.out.println("bingo");
break;//没有break会无限猜下去
} else {
System.out.println("Input number please");
}
}
} catch (Exception e) {
System.out.println("Input a number ,not a String");
e.printStackTrace();
}
}
private static String inputMethod() {
//终端while(true)的方法,但switch似乎不能这么用
//while(true) {
// 语句;
// if(条件式)
// break; // 跳离循环
// ...
//}
while (true) {
Scanner scanner = new Scanner(System.in);
System.out.print("input str :");
String str = scanner.next();
switch (str) {
case "1":
System.out.println("return str is " + str);//用return代替break,方法要有返回值,一个方法里可以有多个return。
return str;
case "2":
System.out.println("return str is " + str);//这里用return是为了中断函数执行,否则会无限输入下去
return str;
case "3":
System.out.println("case is 3");
break;
case "4":
System.out.println("case is 4");
break;
default:
System.out.println("is exception");
break;
}
System.out.println("try again");
}
}
}
猜数字小游戏,switch,while(true),Random,Scanner用法
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Origin blog.csdn.net/djydjy3333/article/details/121489769
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