JSwing和二维数组的数组索引越界

Question

我正在尝试创建一个存储学生考试成绩的程序。

每个学生都有 4 个测试分数，必须存储在一个二维数组中。 JSwing 应用程序将允许用户输入 4 个测试标记，一旦他们单击一个按钮，它会将 4 个标记添加到数组中。

我试图通过不断收到 arrayindexboundexception 来弄清楚如何做到这一点。另外，我什至不确定我是否做得正确。

顺便说一句，这都是在JSwing完成的。

public class StudentGradesView extends FrameView {
    final static int students = 15;
    final static int numOfTest = 4;

    //DELCARING THE 2D ARRAY
    double[][] marks = new double[students][numOfTest];

    public void addInfo() {
        double testScores[] = new double[4];
        String test1, test2, test3, test4;
        double score1, score2, score3, score4;
        int i = 0;
        test1 = testOneIn.getText();
        test2 = testTwoIn.getText();
        test3 = testThreeIn.getText();
        test4 = testFourIn.getText();
        score1 = Double.parseDouble(test1);
        score2 = Double.parseDouble(test2);
        score3 = Double.parseDouble(test3);
        score4 = Double.parseDouble(test4);
        testScores[0] = score1;
        testScores[1] = score2;
        testScores[2] = score3;
        testScores[3] = score4;

        //First for loop starts at in the first row and automatically
        //increments to the next row after the first rows columns are filled
        for (int row = 0; row < marks.length; row++) {

            //Second loop automatically cycles through each column in the
            //current row adding test scores. After this loop finishes
            //the program returns to the first loop and advances to the next 
            //row, at which point it will fill that row with the same test data.
            for (int col = 0; col < 4; col++) {
                marks[row][col] = testScores[i];
                i++;
            }
        }
    }

}

这是我目前所拥有的。任何帮助表示赞赏。

Answer 1

您正在增加i 超出testScores 数组的范围。该数组的长度仅为 4。marks 的第二次迭代将导致 i > testScores.length 给您异常。

考虑更新您的输入以接受学号：

int student = Integer.parseInt(studentIn.getText());

然后您可以只将测试分数输入应用到该学生：

for (int col = 0, i = 0; col < 4; col++, i++) {
    marks[student][col] = testScores[i]; 
}

此外，由于您没有执行双重 for 循环，因此不需要 i 变量，您可以改用 col：

for (int col = 0; col < 4; col++) {
    marks[student][col] = testScores[col]; 
}

Answer 2

对于你原来的问题

for(int row=0; row <marks.length; row++){
        for(int col=0;col <4; col++){
            marks[row][col]= testScores[i];
            i++;
        }

正在增加 i 超出 testScores 的长度。使用这个

for(int row=0; row <marks.length; row++){
            i = 0;
            for(int col=0;col <4; col++){
                marks[row][col]= testScores[i];
                i++;
         }

FWIW，您还可以减少本节中的代码量、变量的数量，并最终减少为变量分配的内存量：

    test1=testOneIn.getText();
    test2=testTwoIn.getText();
    test3=testThreeIn.getText();
    test4=testFourIn.getText();
    score1=Double.parseDouble(test1);
    score2=Double.parseDouble(test2);
    score3=Double.parseDouble(test3);
    score4=Double.parseDouble(test4);
    testScores[0]=score1;
    testScores[1]=score2;
    testScores[2]=score3;
    testScores[3]=score4;

通过这样做

    testScores[0] = Double.parseDouble(testOneIn.getText());

Answer 3

我不确定是否应该添加第二个答案，但它应该是这样的

public class StudentGradesView extends FrameView {
 final static int students=15;
 final static int numOfTest=4;

 //Start with the first student in the 2D array
 private int row = 0;


//DELCARING THE 2D ARRAY
double[][] marks = new double[students][numOfTest];


public void addInfo(){
    double testScores[]=new double[4];
    testScores[0]=Double.parseDouble(testOneIn.getText());
    testScores[1]=Double.parseDouble(testTwoIn.getText());
    testScores[2]=Double.parseDouble(testThreeIn.getText());
    testScores[3]=Double.parseDouble(testFourIn.getText());

    //Add all four test scores to the current student
        for(int col=0;col < testScores.length; col++){
            marks[row][col]= testScores[col];
            }

    //Advance to the next student
    row++;
   }
  }