无法识别负数

Question

import java.util.Scanner;

public class HelloWorld {
   public static void main(String[] args) {
      // Prints "Hello, World" in the terminal window.

      Scanner quest = new Scanner(System.in);enter code here
      System.out.println("How old are you?: ");
      int num = quest.nextInt();

      if (num <= 12){
        System.out.println("You are too young to be on the computer!!!!");
      } else if (num >=13 && num <= 17){
        System.out.println("Welcome young teen");
      } else if (17 < num && num <= 60){
        System.out.println("Welcome adult");
      } else if (60 < num){
        System.out.println("Welcome senior citizen!!");
      } else{
        System.out.println("Invalid age.");
      }

   }
}

当我输入一个负数时，它就属于＆＃34;你太年轻了，不能上电脑!!!!＆＃34;而不是显示＆＃34;无效年龄。＆＃34;我试过改变条件，但它似乎不起作用。

Answer 1

由于负数小于12，您可以通过测试负值并通过依赖之前的if-else检查来消除&&块来简化您的int num = quest.nextInt(); if (num < 0) { // <-- negative values. System.out.println("Invalid age."); } else if (num <= 12) { // <-- (0, 12) System.out.println("You are too young to be on the computer!!!!"); } else if (num <= 17) { // <-- (13, 17) System.out.println("Welcome young teen"); } else if (num <= 60) { // <-- (18, 60) System.out.println("Welcome adult"); } else { // <-- greater than 60 System.out.println("Welcome senior citizen!!"); } 块链检查条件。像，

{{1}}

Answer 2

您应该使用if(Condition) { //Code }语句将其作为第一个条件。好吧，我对代码进行了一次运行，并对你的代码进行了一些调整。

import java.util.Scanner;

public class HelloWorld {
   public static void main(String[] args) {
      // Prints "Hello, World" in the terminal window.

      Scanner quest = new Scanner(System.in); //enter code here
      System.out.println("How old are you?: ");
      int num = quest.nextInt();

      if (num <= 0) {
          System.out.println("Invalid age.");
      } else if (num <= 12){
        System.out.println("You are too young to be on the computer!!!!");
      } else if (num >=13 && num <= 17){
        System.out.println("Welcome young teen");
      } else if (17 < num && num <= 60){
        System.out.println("Welcome adult");
      } else if (60 < num){
        System.out.println("Welcome senior citizen!!");
      } 
   }
}