java - 在不使用 arraylist 的情况下使用 compareTo 在 Java 上排序

Question

我是 Java 的初学者，我一直在尝试使用 compareTo 方法对三个城市进行排序。我的三个测试词是 Legion、LSD 和 Chunkey。为了识别错误，我为每个输出可能性设置了 1-6 的数字。对于输出 1，它是 (Chunkey, LSD, Legion)，2 = (legion, LSD, Chunkey, 4 = (Chunkey, Legion, LSD)。当我相信我遵循正确的逻辑时，输出往往没有意义比较两个字符串，并且值为负值，然后第一个值在前，然后是第二个值。但即使这样做，它的顺序也不正确。请帮忙!谢谢!

import java.util.Scanner;
public class OrderingCity {
public static void main (String []args){
    Scanner input = new Scanner(System.in);

    System.out.println("Enter the First City");
    String c1 = input.nextLine();
    System.out.println("Enter the Second City");
    String c2 = input.nextLine();
    System.out.println("Enter the Third City");
    String c3 = input.nextLine();

    //When the value is less than 0, the first value is first while the second value is second.

    //When the first city is compared to the second and if it returns a negative value (<0) then
    //the first city comes first and when the value of the second city is compared to the third
    //city and it returns a negative value then the second city comes before the third city
    if (c1.compareTo(c2) < 0 && c2.compareTo(c3) < 0){ 
        System.out.println(c1 + " 1 " + c2 + " " + c3);
    }

    //When the first city is compared to the second and it returns a positive value (>0) then
    //the second city comes first and when the value of the first city is compared to the third
    //city and it returns a positive value (>0) then third city comes before the first.
    else if (c1.compareTo(c2) > 0 && c1.compareTo(c3) > 0){
        System.out.println(c2 + " 2 " + c3 + " " + c1);
    }


    else if (c2.compareTo(c3) < 0 && c3.compareTo(c1) < 0){
        System.out.println(c2 + " 3 " + c3 + " " + c1);
    }


    else if (c2.compareTo(c3) > 0 && c2.compareTo(c1) > 0){
        System.out.println(c3 + " 4 " + c1 + " " + c2 );
    }

    else if (c3.compareTo(c1) < 0 && c1.compareTo(c2) < 0){
        System.out.println(c3 + " 5 " + c1 + " " + c2);
    }

    else if (c3.compareTo(c1) > 0 && c3.compareTo(c2) > 0) { 
        System.out.println(c1 + " 6 " + c2 + " " + c3);
    }


}
}

Answer 1

这应该有帮助:

import java.util.Scanner;

public class OrderingCity {
    public static void main(String[] args) {

        Scanner input = new Scanner(System.in);

        System.out.println("Enter the First City");
        String c1 = input.nextLine();

        System.out.println("Enter the Second City");
        String c2 = input.nextLine();

        System.out.println("Enter the Third City");
        String c3 = input.nextLine();

        String temp;

        // Example:  c b a

        // c > b
        if (c1.compareTo(c2) > 0) {
            temp = c1;
            c1 = c2;
            c2 = temp;
        }
        // b c a

        // c > a
        if (c2.compareTo(c3) > 0) {
            temp = c2;
            c2 = c3;
            c3 = temp;
        }
        // b a c

        // a > b
        if (c1.compareTo(c2) > 0) {
            temp = c1;
            c1 = c2;
            c2 = temp;
        }
        // a b c

        System.out.printf("%s %s %s", c1, c2, c3);
    }
}