Question

我想按字母顺序排列我的琴弦。我的代码也可以。但是，当我输入汉斯（Hans），安娜（Anna）和麦克斯（Max）字符串时，他同时给了我“ if”和“ else” println。错误在哪里？

import java.util.Scanner;

class ersteAufgabe {

public static void main(String args[]) {

          Scanner scan = new Scanner(System.in);
          String s1 = scan.nextLine();
          String s2 = scan.nextLine();
          String s3 = scan.nextLine();
          if (s1.compareTo(s2) < 0 & s1.compareTo(s3) < 0 & s2.compareTo(s1) > 0 & s2.compareTo(s3) < 0 & s3.compareTo(s1) > 0 & s3.compareTo(s2) > 0) 
          {
            System.out.println("Ordnung:" + s1 +" "+ s2 +" " + s3);  
          }
          if (s1.compareTo(s2) < 0 & s1.compareTo(s3) < 0 & s2.compareTo(s1) > 0 & s2.compareTo(s3) > 0 & s3.compareTo(s1) > 0 & s3.compareTo(s2) < 0) 
          {
            System.out.println("Ordnung:" + s1 +" "+ s3 +" " + s2);  
          }
          if (s1.compareTo(s2) > 0 & s1.compareTo(s3) < 0 & s2.compareTo(s3) < 0 & s2.compareTo(s1) < 0 & s3.compareTo(s1) > 0 & s3.compareTo(s2) > 0) 
          {
            System.out.println("Ordnung:" + s2 +" "+ s1 +" " + s3);  
          }
          if (s1.compareTo(s2) > 0 & s1.compareTo(s3) > 0 & s2.compareTo(s1) < 0 & s2.compareTo(s3) < 0 & s3.compareTo(s1) < 0 & s3.compareTo(s2) > 0) 
          {
            System.out.println("Ordnung:" + s2 +" "+ s3 +" " + s1);  
          }
          if (s1.compareTo(s2) < 0 & s1.compareTo(s3) > 0 & s2.compareTo(s3) > 0 & s2.compareTo(s1) > 0 & s3.compareTo(s1) < 0 & s3.compareTo(s2) < 0)
          {
            System.out.println("Ordnung:" + s3 +" "+ s1 +" " + s2);  
          }
          if (s1.compareTo(s2) > 0 & s1.compareTo(s3) > 0 & s2.compareTo(s1) < 0 & s2.compareTo(s3) > 0 & s3.compareTo(s2) < 0 & s3.compareTo(s1) < 0)
          {
            System.out.println("Ordnung:" + s3 +" "+ s2 +" " + s1);  
          } else{
              System.out.println("Ungueltige Eingabe");
          }

    }
 }

Answer 1

您代码中的else仅连接到最后一个if。这意味着，如果其他if中的一个为true（而最后一个if为false），则也将执行else。所以试试这个：

public static void main(String args[]) {

          Scanner scan = new Scanner(System.in);
          String s1 = scan.nextLine();
          String s2 = scan.nextLine();
          String s3 = scan.nextLine();
          if (s1.compareTo(s2) < 0 & s1.compareTo(s3) < 0 & s2.compareTo(s1) > 0 & s2.compareTo(s3) < 0 & s3.compareTo(s1) > 0 & s3.compareTo(s2) > 0) 
          {
            System.out.println("Ordnung:" + s1 +" "+ s2 +" " + s3);  
          }
          else if (s1.compareTo(s2) < 0 & s1.compareTo(s3) < 0 & s2.compareTo(s1) > 0 & s2.compareTo(s3) > 0 & s3.compareTo(s1) > 0 & s3.compareTo(s2) < 0) 
          {
            System.out.println("Ordnung:" + s1 +" "+ s3 +" " + s2);  
          }
          else if (s1.compareTo(s2) > 0 & s1.compareTo(s3) < 0 & s2.compareTo(s3) < 0 & s2.compareTo(s1) < 0 & s3.compareTo(s1) > 0 & s3.compareTo(s2) > 0) 
          {
            System.out.println("Ordnung:" + s2 +" "+ s1 +" " + s3);  
          }
          else if (s1.compareTo(s2) > 0 & s1.compareTo(s3) > 0 & s2.compareTo(s1) < 0 & s2.compareTo(s3) < 0 & s3.compareTo(s1) < 0 & s3.compareTo(s2) > 0) 
          {
            System.out.println("Ordnung:" + s2 +" "+ s3 +" " + s1);  
          }
          else if (s1.compareTo(s2) < 0 & s1.compareTo(s3) > 0 & s2.compareTo(s3) > 0 & s2.compareTo(s1) > 0 & s3.compareTo(s1) < 0 & s3.compareTo(s2) < 0)
          {
            System.out.println("Ordnung:" + s3 +" "+ s1 +" " + s2);  
          }
          else if (s1.compareTo(s2) > 0 & s1.compareTo(s3) > 0 & s2.compareTo(s1) < 0 & s2.compareTo(s3) > 0 & s3.compareTo(s2) < 0 & s3.compareTo(s1) < 0)
          {
            System.out.println("Ordnung:" + s3 +" "+ s2 +" " + s1);  
          } else{
              System.out.println("Ungueltige Eingabe");
          }
    }
 }

Answer 2

您的代码是一系列if，除了您的else所附的最后一个代码之外，它们都是独立的。如果您希望最后一个else充当整个链的else，则需要将中间的if转换为if else。

if (condition1) {
    // Do something...
} else if (condition2) {
    // Do something else...
} else {
    // Do something if neither condition1 nor condition2
}

旁注：我看到您使用的是按位和运算符（&），而不是布尔值和运算符（&&）。尽管它可能适合您的情况，但我强烈警告您不要将按位运算符用于除按位操纵以外的任何操作，因为它的优先级高于不等式，而布尔运算符的优先级较低，这可能会导致意外结果。

Answer 3

您需要将控制语句更改为

 if (s1.compareTo(s2) < 0 & s1.compareTo(s3) < 0 & s2.compareTo(s1) > 0 & s2.compareTo(s3) < 0 & s3.compareTo(s1) > 0 & s3.compareTo(s2) > 0) {
            System.out.println("Ordnung:" + s1 + " " + s2 + " " + s3);
        }
        else if (s1.compareTo(s2) < 0 & s1.compareTo(s3) < 0 & s2.compareTo(s1) > 0 & s2.compareTo(s3) > 0 & s3.compareTo(s1) > 0 & s3.compareTo(s2) < 0) {
            System.out.println("Ordnung:" + s1 + " " + s3 + " " + s2);
        }
        else if (s1.compareTo(s2) > 0 & s1.compareTo(s3) < 0 & s2.compareTo(s3) < 0 & s2.compareTo(s1) < 0 & s3.compareTo(s1) > 0 & s3.compareTo(s2) > 0) {
            System.out.println("Ordnung:" + s2 + " " + s1 + " " + s3);
        }
        else if (s1.compareTo(s2) > 0 & s1.compareTo(s3) > 0 & s2.compareTo(s1) < 0 & s2.compareTo(s3) < 0 & s3.compareTo(s1) < 0 & s3.compareTo(s2) > 0) {
            System.out.println("Ordnung:" + s2 + " " + s3 + " " + s1);
        }
        else if (s1.compareTo(s2) < 0 & s1.compareTo(s3) > 0 & s2.compareTo(s3) > 0 & s2.compareTo(s1) > 0 & s3.compareTo(s1) < 0 & s3.compareTo(s2) < 0) {
            System.out.println("Ordnung:" + s3 + " " + s1 + " " + s2);
        }
        else if (s1.compareTo(s2) > 0 & s1.compareTo(s3) > 0 & s2.compareTo(s1) < 0 & s2.compareTo(s3) > 0 & s3.compareTo(s2) < 0 & s3.compareTo(s1) < 0) {
            System.out.println("Ordnung:" + s3 + " " + s2 + " " + s1);
        } else {
            System.out.println("Ungueltige Eingabe");
        }

因此只有其中之一被执行。您当前拥有的是多个不相关的if语句！

Java输出是否，否则？

3 个答案: