java - 内部编译器错误？

Question

目前这段代码还没有完成，我只是在编写随机生成一个 3x3 数组所需的方法，每个空格都有不同的单个数字。但是，我在第一行收到一个错误，上面写着 Internal compiler error: java.lang.NullPointerException at org.eclipse.jdt.internal.compiler.ast.ReferenceExpression.copy(ReferenceExpression.java:141)。我不太确定这个错误是什么意思，因为我只是一个初出茅庐的程序员。我该如何解决这个错误？

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

    }

    public static int sumRows(int[][] array) {
        int totalRowOne;
        int totalRowTwo;
        int totalRowThree;

        totalRowOne = array[0][0] + array[0][1] + array[0][2];
        totalRowTwo = array[1][0] + array[1][1] + array[1][2];
        totalRowThree = array[2][0] + array[2][1] + array[2][2];

        if(totalRowOne == totalRowTwo && totalRowOne == totalRowThree) {
            return totalRowOne;
        }
        else {
            return -1;
        }
    }

    public static int sumColumns(int[][] array) {
        int totalColumnOne;
        int totalColumnTwo;
        int totalColumnThree;

        totalColumnOne = array[0][0] + array[1][0] + array[2][0];
        totalColumnTwo = array[0][1] + array[1][1] + array[2][0];
        totalColumnThree = array[0][2] + array[1][2] + array[2][2];

        if(totalColumnOne == totalColumnTwo && totalColumnOne == totalColumnThree) {
            return totalColumnOne;
        }
        else {
            return -1;
        }
    }

    public static int sumDiagonals(int[][] array) {
        int totalDiagonalOne;
        int totalDiagonalTwo;

        totalDiagonalOne = array[0][0] + array[1][1] + array[2][2];
        totalDiagonalTwo = array[0][2] + array[1][1] + array[2][0];

        if(totalDiagonalOne == totalDiagonalTwo) {
            return totalDiagonalOne;
        }
        else {
            return -1;
        }
    }

    public static boolean isUnique(int[][] array, int num) {
        if(num == array[0][0] || num == array[0][1] || num == array[0][2] ||
           num == array[1][0] || num == array[1][1] || num == array[1][2] ||
           num == array[2][0] || num == array[2][1] || num == array[2][2]) {
            return true;
        }
        else {
            return false;
        }
    }

    public static void displayMagicSquare(int[][] array) {
        int counter1;
        int counter2;

        for(counter1 = 0; counter1 < 3; counter1++) {
            for(counter2 = 0; counter2 < 3; counter2++) {
                System.out.print(array[counter1][counter2]);
            }
            System.out.print("/n");
        }
    }

    public static int[][] fillMatrix(int[][] array) {
        int numberOne;
        int numberTwo;
        int numberThree;
        int numberFour;
        int numberFive;
        int numberSix;
        int numberSeven;
        int numberEight;
        int numberNine;

        array[0][0] = 0;
        array[0][1] = 0;
        array[0][2] = 0;
        array[1][0] = 0;
        array[1][1] = 0;
        array[1][2] = 0;
        array[2][0] = 0;
        array[2][1] = 0;
        array[2][2] = 0;

        numberOne = (int)(Math.random() * 8 + 1);
        do {
            numberTwo = (int)(Math.random() * 8 + 1);
        } while(numberTwo == numberOne);

        do {
        numberThree = (int)(Math.random() * 8 + 1);
        } while(numberThree == numberTwo || numberThree == numberOne);

        do {
        numberFour = (int)(Math.random() * 8 + 1);
        } while(numberFour == numberThree || numberFour == numberTwo || numberFour == numberOne);

        do {    
        numberFive = (int)(Math.random() * 8 + 1);
        } while (numberFive == numberFour || numberFive == numberThree || numberFive == numberTwo ||
                 numberFive == numberOne);

        do {
        numberSix = (int)(Math.random() * 8 + 1);
        } while(numberSix == numberFive || numberSix == numberFour || numberSix == numberThree ||
                numberSix == numberTwo ||numberSix == numberOne);

        do {
        numberSeven = (int)(Math.random() * 8 + 1);
        } while(numberSeven == numberSix || numberSeven == numberFive || numberSeven == numberFour ||
                numberSeven == numberThree ||numberSeven == numberTwo ||numberSeven == numberOne);

        do {
        numberEight = (int)(Math.random() * 8 + 1);
        } while(numberEight == numberSeven || numberEight == numberSix || numberEight == numberFive ||
                numberEight == numberFour ||numberEight == numberThree ||numberEight == numberTwo ||
                numberEight == numberOne);

        do {
        numberNine = (int)(Math.random() * 8 + 1);
        } while(numberNine == numberEight || numberNine == numberSeven || numberNine == numberSix ||
                numberNine == numberFive || numberNine == numberFour ||numberNine == numberThree ||
                numberNine == numberTwo || numberNine == numberOne);

        array[0][0] = numberOne;
        array[0][1] = numberTwo;
        array[0][2] = numberThree;
        array[1][0] = numberFour;
        array[1][1] = numberFive;
        array[1][2] = numberSix;
        array[2][0] = numberSeven;
        array[2][1] = numberEight;
        array[2][2] = numberNine;

        return array;
    }

    public static boolean isMagicSquare(int[][] array) {
        if(sumRows(int[][] array) == sumColumns(int[][] array) && sumColumns(int[][] array) == sumDiagonals(int[][] array)) {
            return true;
        }
        else {
            return false;
        }
    }

}

Answer 1

Internal compiler error: java.lang.NullPointerException at org.eclipse.jdt.internal.compiler.ast.ReferenceExpression.copy(ReferenceExpression.java:141)

意味着 Eclipse Java 编译器的实际内部结构非常困惑，以至于他们取消引用了一个空指针。根据定义，这是 Eclipse 中的错误。最有可能的是，由于代码中的某些错误，您遇到了这个错误；如果一个小的、正确的 Java 类命中其中之一，那将是非常令人惊讶的。

您可以尝试使用真正的 JDK 编译您的代码，它可能会告诉您需要修复的地方。一般来说，您不应该依赖 IDE 作为您唯一的构建工具；有一天你会想要从命令行进行可重复的构建，你会想要学习 ant、Maven 或 gradle。也许各种编译网站之一可以方便地满足您的即时需求。