为什么我的冒泡排序不起作用？ Java

Question

第一次发帖！我有一项作业要求我编写一个 java 程序，该程序从文本文件中读取数据并根据分数及其首字母对其进行排序。文本文件如下：

John Doe 75
Joe Blow 65
Mary Smith 80
John Green 82
Jill White 97

这是我的代码：

import java.util.Scanner;
public class HelloWorld{
public static void main(String[] args) throws Exception{
    String[] firstName = new String[5];
    String[] lastName = new String[5];
    int score[] = new int[5];
    java.io.File file = new java.io.File("data.txt");
    Scanner input = new Scanner(file);

        int c=0;
        while(input.hasNext()){
            firstName[c] = input.next();
            lastName[c] = input.next();
            score[c] = input.nextInt();
            c++;
        }
        input.close();

    MichaelBubbleSort(score);
    for(int x=4;x>=0;x--){
        System.out.print(firstName[x].substring(0,1) + lastName[x].substring(0,1) + " " + score[x]);
        System.out.println();
    }
}


public static void MichaelBubbleSort(int[] arr){
    int temp;
    for(int i=0; i < arr.length-1; i++){

        for(int j=1; j < arr.length-i; j++){
            if(arr[j-1] > arr[j]){
                temp=arr[j-1];
                arr[j-1] = arr[j];
                arr[j] = temp;
       }
     }
   }
 }

}

但出于某种原因，它总是显示为：

输出应该是：

JW 97
JG 82
MS 80
JD 75
JB 65

这种情况一直发生的原因是什么？

Answer 1

这是根据您的代码的解决方案。但代码必须比这个更好。你应该使用集合类。在此代码中，您需要相应地交换名称。

import java.util.Scanner;

public class HelloWorld{
    public static void main(String[] args) throws Exception {
        String[] firstName = new String[5];
        String[] lastName = new String[5];
        int score[] = new int[5];
        java.io.File file = new java.io.File("D:\test.txt");
        Scanner input = new Scanner(file);

        int c = 0;
        while (input.hasNext()) {
            firstName[c] = input.next();
            lastName[c] = input.next();
            score[c] = input.nextInt();
            c++;
        }
        input.close();

        MichaelBubbleSort(score,firstName,lastName);
        for (int x = 4; x >= 0; x--) {
            System.out.print(firstName[x].substring(0, 1)
                    + lastName[x].substring(0, 1) + " " + score[x]);
            System.out.println();
        }
    }

    public static void MichaelBubbleSort(int[] arr,String[] firstName, String[] lastName) {
        int temp;
        String tempFirstName,tempLastName;
        for (int i = 0; i < arr.length - 1; i++) {

            for (int j = 1; j < arr.length - i; j++) {
                if (arr[j - 1] > arr[j]) {
                    temp = arr[j - 1];
                    arr[j - 1] = arr[j];
                    arr[j] = temp;

                    tempFirstName = firstName[j -1];
                    firstName[j - 1] = firstName[j];
                    firstName[j] = tempFirstName;

                    tempLastName = lastName[j -1];
                    lastName[j - 1] = lastName[j];
                    lastName[j] = tempLastName;
                }
            }
        }
    }
}

Answer 2

发生这种情况是因为您没有根据分数对名称进行排序。我建议使用对象数组来存储数据，然后像这样使用冒泡排序对对象数组进行排序：

public class B{

public static void MichaelBubbleSort(Person[] arr){
    Person temp;
    for(int i=0; i < arr.length-1; i++){

        for(int j=1; j < arr.length-i; j++){
            if(arr[j-1].score > arr[j].score){
                temp=arr[j-1];
                arr[j-1] = arr[j];
                arr[j] = temp;
            }
        }
    }
}

public static void main(String x[]){
    Person [] a={new Person("John","Doe",75),new Person("Joe","Blow",65),new Person("Mary","Smith",80),new Person("John","Green", 82),new Person("Jill","White", 97)};
    MichaelBubbleSort(a);

    for(Person i:a){
        System.out.println(i.FirstName+" "+i.LastName+" "+i.score);
    }

}
}

保存数据的对象class

class Person{
    int score;
    String FirstName;
    String LastName;

    Person(String FName,String LName,int Score){
        this.score=Score;
        this.FirstName=FName;
        this.LastName=LName;
    }
}

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