如何相对于彼此对两个数组进行排序？

Question

我正在尝试制作一个学生成绩计划，其中有 2 个数组：String[] Student 和 double[] Grade。 我将它们克隆为一个已排序的数组和一个未排序的数组。

数组：

public class Testcode {
    public static void main(String[] args) {
        String ArrN[] = {"Garcia", "Magsilang", "Magbag"};
        double ArrG[] = {2.5, 1.25, 1.5};

        String ArrN2[] = ArrN.clone();
        double ArrG2[] = ArrG.clone();

        Arrays.sort(ArrN2);
        Arrays.sort(ArrG2);

        System.out.println(Arrays.toString(ArrN1));
        System.out.println(Arrays.toString(ArrN2));
        System.out.println(Arrays.toString(ArrG2));
        System.out.println(Arrays.toString(ArrG2));
    }
}

现在，我如何制作如下图所示的输出（按等级排序）

- 1.25               Magsilang
- 1.5                Magbag
- 2.5                Garcia

或（学生排序）

- Garcia             2.5
- Magbag             1.5
- Magsilang          1.25

Answer 1

因为您不只是单独处理姓名和成绩。我建议为您的问题创建一个StudentGrade 类，如下所示：

private static class StudentGrade {
    String name;
    double grade;

    public StudentGrade(String n, double g) {
        this.name = n;
        this.grade = g;
    }
}

您可以创建一个 StudentGrade[] 数组，并使用适合您用例的任何字段对其进行排序。我用name 和grade 对其进行了排序，我能够看到预期的输出；

StudentGrade[] studentGrades = new StudentGrade[] {
        new StudentGrade("Garcia", 2.5),
        new StudentGrade("Magsilang", 1.25),
        new StudentGrade("Magbag", 1.5)
};

// Sort By Name
System.out.println("(Student Sorted):");
Arrays.sort(studentGrades, Comparator.comparing(o -> o.name));
printStudentGrades(studentGrades);

// Sort by Grade
System.out.println("(Grade Sorted):");
Arrays.sort(studentGrades, Comparator.comparing(o -> o.grade));
printStudentGrades(studentGrades);

这会打印这个输出：

(Student Sorted):
Garcia 2.5
Magbag 1.5
Magsilang 1.25
(Grade Sorted):
Magsilang 1.25
Magbag 1.5
Garcia 2.5

Answer 2

正如其他人所说，如果你有一个单独的类 StudentGrade，它包含名称和等级，然后你利用已经实现的算法 Collections.sort，它从 Java 8 接受你的类的方法引用，这更有意义.

代码如下：

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

class StudentGrade {

    private String name;
    private double grade;

    public StudentGrade(String name, double grade) {
        this.name = name;
        this.grade = grade;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public double getGrade() {
        return grade;
    }

    public void setGrade(double grade) {
        this.grade = grade;
    }
}

public class Testcode {

    public static void main(String[] args) {

        List<StudentGrade> students = new ArrayList<>();

        students.add(new StudentGrade("Garcia", 2.5));
        students.add(new StudentGrade("Magsilang", 1.5));
        students.add(new StudentGrade("Magbag", 1.25));

        Collections.sort(students, Comparator.comparing(StudentGrade::getGrade));
        System.out.println("Grade Sorted");
        for (StudentGrade studentGrade : students) {
            System.out.println(studentGrade.getGrade() + " " + studentGrade.getName());
        }

        Collections.sort(students, Comparator.comparing(StudentGrade::getName));
        System.out.println("\nStudent Sorted");
        for (StudentGrade studentGrade : students) {
            System.out.println(studentGrade.getName() + " " + studentGrade.getGrade());
        }

    }
}

输出是：

Grade Sorted
1.25 Magbag
1.5 Magsilang
2.5 Garcia

Student Sorted
Garcia 2.5
Magbag 1.25
Magsilang 1.5

Answer 3

我已尝试获取您的第二个输出。使用Bubble sort对数组进行排序！

class TestCode {
    public static void main(String[] args) {
        String ArrN[] = {"Garcia", "Magsilang", "Magbag"};
        double ArrG[] = {2.5, 1.25, 1.5};

        //bubble sort based on ArrG array
        for (int i = 0; i < ArrG.length - 1; i++) {
            for (int j = 0; j < ArrG.length - i - 1; j++) {
                if (ArrG[j] < ArrG[j + 1]) {
                    double temp = ArrG[j];
                    ArrG[j] = ArrG[j + 1];
                    ArrG[j + 1] = temp;

                    String tempN = ArrN[j];
                    ArrN[j] = ArrN[j + 1];
                    ArrN[j + 1] = tempN;
                }
            }
        }

        // print the array
        for (int i = 0; i < ArrG.length; i++) {
            System.out.println(ArrN[i] + " " + ArrG[i]);
        }
    }
}

输出：

Garcia 2.5
Magbag 1.5
Magsilang 1.25

这是一个基本的方法！您还可以使用Class 或内置的Array() 方法！

Answer 4

要获得两个数组相对于彼此的排序副本，您可以首先成对链接这些数组的元素，然后对这些对进行排序 - 你得到一个排序列表。作为每对的容器，您可以使用Map.Entry、数组或某些类。例如：

String[] arrN = {"Garcia", "Magsilang", "Magbag"};
double[] arrG = {2.5, 1.25, 1.5};

List<Map.Entry<String, Double>> list = IntStream
        // assuming the two arrays are the same length,
        // iterate over the indices of the first array
        .range(0, arrN.length)
        // link a pair of two elements
        .mapToObj(i -> Map.entry(arrN[i], arrG[i]))
        // collect a list of map entries
        .collect(Collectors.toList());

// sort by name
list.sort(Map.Entry.comparingByKey());
list.forEach(System.out::println);
//Garcia=2.5
//Magbag=1.5
//Magsilang=1.25

// sort by grades
list.sort(Map.Entry.comparingByValue());
list.forEach(System.out::println);
//Magsilang=1.25
//Magbag=1.5
//Garcia=2.5

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^{另见：How do I relate one array input to another?}