Java 数组排序与索引输出教程

import java.util.Scanner;

public class ArrayIntro2 {

    public static void main(String[] args) {
        //integer array
        int[] TestGrades = new int[25];

        //creating object of ArrayIntro2T
        ArrayIntro2T pass = new ArrayIntro2T(TestGrades, 0, 0, 0);

        //getting total and filling array
        int scoreCount = ArrayIntro2T.FillArray(TestGrades, 0);

        //get average score
        double avg = pass.ComputeAverage(TestGrades, scoreCount);

        //outputting table
        ArrayIntro2T.OutputArray(TestGrades, scoreCount, avg);

        // Outputting sorted table
        ArrayIntro2T.selectionSort(TestGrades, scoreCount); // Sort only valid scores
        ArrayIntro2T.OutputSortedArray(TestGrades, scoreCount);
    }
}

//new class to store methods
class ArrayIntro2T {
    //variable declaration

    double CalcAvg = 0;
    int ScoreTotal = 0;
    int ScoreCount = 0;
    int[] TestGrades = new int[25];


    //constructor
    public ArrayIntro2T(int[] TestGradesT, int ScoreCountT, double CalcAvgT, int ScoreTotalT) {
        TestGrades = TestGradesT;
        ScoreCount = ScoreCountT;
        CalcAvg = CalcAvgT;
        ScoreTotal = ScoreTotalT;
    }

    //method to fill array
    public static int FillArray(int[] TestGrades, int ScoreCount) {

        Scanner scan = new Scanner(System.in);

        System.out.println("Please enter test scores one at a time, up to 25 values or enter -1 to quit");
        TestGrades[ScoreCount] = scan.nextInt();

        if (TestGrades[ScoreCount] == -1) {
            System.out.println("You have chosen to quit ");
        }

        while (TestGrades[ScoreCount] >= 0 && ScoreCount < 25) { // Corrected the loop condition
            ScoreCount++;
            if (ScoreCount < 25) { // Added check to prevent ArrayIndexOutOfBoundsException
                System.out.println("Enter the next test score or -1 to finish ");
                TestGrades[ScoreCount] = scan.nextInt();
            } else {
                System.out.println("Maximum number of scores reached.");
                break;
            }
        }
        return ScoreCount;
    }

    //method to compute average
    public double ComputeAverage(int[] TestGrades, int ScoreCount) {

        for (int i = 0; i < ScoreCount; i++) {
            ScoreTotal += TestGrades[i];
            CalcAvg = (double) ScoreTotal / (double) ScoreCount;
        }

        return CalcAvg;

    }

    public static void selectionSort(int[] TestGrades, int scoreCount) {
        int startScan, index, minIndex, minValue;
        int[] indices = new int[scoreCount];
        for (int i = 0; i < scoreCount; i++) {
            indices[i] = i; // Initialize indices array
        }

        for (startScan = 0; startScan < (scoreCount - 1); startScan++) {
            minIndex = startScan;
            minValue = TestGrades[indices[startScan]]; // Use indices array for comparison
            for (index = startScan + 1; index < scoreCount; index++) {
                if (TestGrades[indices[index]] < minValue) { // Use indices array for comparison
                    minValue = TestGrades[indices[index]];
                    minIndex = index;
                }
            }
            // Swap both TestGrades and indices
            int temp = indices[startScan];
            indices[startScan] = indices[minIndex];
            indices[minIndex] = temp;
        }
        // Reorder TestGrades based on sorted indices
        int[] sortedGrades = new int[scoreCount];
        for (int i = 0; i < scoreCount; i++) {
            sortedGrades[i] = TestGrades[indices[i]];
        }
        // Copy the sorted grades back to TestGrades array
        System.arraycopy(sortedGrades, 0, TestGrades, 0, scoreCount);
    }

    //method to output scores and average
    public static void OutputArray(int[] TestGrades, int ScoreCount, double CalcAvg) {

        System.out.println("Grade Number\t\tGrade Value");

        for (int i = 0; i < ScoreCount; i++) {
            System.out.println((i + 1) + "\t" + "\t" + "\t" + TestGrades[i]);
        }

        System.out.printf("Calculated Average\t" + "%.2f%%\n", CalcAvg); // Added newline for better formatting
    }

    public static void OutputSortedArray(int[] TestGrades, int scoreCount) {
        System.out.println("\nTable of sorted test scores");
        System.out.println("Grade Number\t\tGrade Value");
        for (int i = 0; i < scoreCount; i++) {
            System.out.println((i + 1) + "\t" + "\t" + "\t" + TestGrades[i]);
        }
    }
}