Day13 (switch, decompile, view class file)

switch multiple selection structure

• Another implementation of the multiple-choice structure is the switch case statement.

• The switch case statement determines whether a variable is equal to a certain value in a series of values, and each value is called a branch.

• The variable type in the switch statement can be:

  1. byte, short, int or char
  2. Starting from Java SE 7 switch supports string String type
  3. At the same time, the case label must be a string constant or literal.

• grammar:

switch(expression){
    
    case value: //语句 
break;//可选
case value: //语句
break;//可选
//可以有任意数量的case语句
default://可选
//语句
}

import java.util.Scanner;
public class A0116 {
    
    
    //case穿透现象：  如果没有break语句；在case匹配成功后继续输出
    //switch是匹配一个具体的值
        public static void main(String[] args) {
    
    
        Scanner a = new Scanner(System.in);
        System.out.println("你最喜欢什么季节");
        String weather = a.nextLine();
                switch(weather){
    
    
            case "春天":
                System.out.println("春天在哪里呀");
            break;//可选 （不写会穿透）
            case "夏天":
                System.out.println("蚊子咬死你呀");
                break;
            case "秋天":
                System.out.println("冬天等着你呀");
                break;
            case "冬天":
                System.out.println("你真不怕冷呀");
                break;
            default://可选
                System.out.println("季节，你懂？");
                a.close();
run：
你最喜欢什么天气
冬天
你真不怕冷呀

Decompile, view the class file

Decompile java-class (bytecode file) ----- Decompile (via IDEA)

To view the class file, click on the project structure and copy the path:

After finding the corresponding class file, copy the class file to the folder where java is stored, and then you can view the code through IDEA