学习Java课程笔记day2

程序流程控制循环结构减少代码的重复编写、灵活的控制程序执行forwhiledo-whiledo while可以用来抢票。和c语言一样跳过死循环for( ; ; ){}while(true){}do{}while(true)循环嵌套break和continuebreak跳出并结束当前所在循环执行。结束所有continue用于跳过当前循环的当次执行直接进入循环的下一次执行。继续下一次package com.itheima.branch; public class breakandcontinue { //弄清楚continue和break的作用 public static void main(String[] args) { for (int i 0; i 10; i) { if (i 5) { break; } System.out.println(i); } System.out.println(循环结束); for (int i 0; i 10; i) { if (i 5) { continue; } System.out.println(i); } System.out.println(循环结束); } }练习简单计算器package com.itheima.branch; import java.util.Scanner; public class computercode { public static void main(String[] args) { //制作一个简单计算器 Scanner scanner new Scanner(System.in); System.out.println(请输入第一个数字); int a scanner.nextInt(); System.out.println(请输入第二个数字); int b scanner.nextInt(); System.out.println(请输入操作符); char operator scanner.next().charAt(0); int result 0; switch (operator) { case : result a b; break; case -: result a - b; break; case *: result a * b; break; case /: result a / b; break; default: System.out.println(输入错误); } System.out.println(result result); } }猜数字package com.itheima.branch; import java.util.Scanner; public class guessnumcode { public static void main(String[] args) { int num (int)(Math.random() * 100) 1; Scanner scanner new Scanner(System.in); while(true){ System.out.print(请输入猜测数字); int guess scanner.nextInt(); if(guess num){ System.out.println(恭喜猜对了); break; }else if(guess num){ System.out.println(猜大了); }else{ System.out.println(猜小了); } } System.out.println(游戏结束); scanner.close(); } }注释1.Math.random()为内置方法返回[0,1)的随机小数。 2.(int)强制为一个整数。