目前这段代码还没有完成，我只是编写了随机生成一个3x3数组所需的方法，每个空格中有一个不同的单个数字。但是，我在Internal compiler error: java.lang.NullPointerException at org.eclipse.jdt.internal.compiler.ast.ReferenceExpression.copy(ReferenceExpression.java:141)的第一行收到错误。我不太确定这个错误意味着什么，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;
}
}
}
答案 0 :(得分：3)
Internal compiler error: java.lang.NullPointerException at org.eclipse.jdt.internal.compiler.ast.ReferenceExpression.copy(ReferenceExpression.java:141)
意味着Eclipse Java Compiler的实际内部内容非常混乱，以至于它们取消引用了空指针。根据定义，这是Eclipse中的一个错误。最有可能的是，你因为代码中的一些错误而遇到了这个错误;如果一个小的，正确的Java类击中其中一个，那将是非常令人惊讶的。
您可以尝试使用真正的JDK编译代码，它可能会告诉您需要修复的内容。通常，您不应该依赖IDE作为唯一的构建工具;有一天你会希望从命令行拥有可重复的构建，并且你想学习ant，Maven或gradle。也许各种编译网站中的一个可以方便您的直接需求。
答案 1 :(得分：0)
您的代码存在一些编译问题。此外，您的代码将在下面的代码片段中遇到无限循环。 Math.random()生成的值小于1.假设Math.random()生成的最大值为0.999，则(Math.random() * 8)的结果为7.992。 (Math.random() * 8)的结果永远不会等于或大于8.所以(int) (Math.random() * 8 + 1)的最大值永远不会大于8，因为你不是(Math.random() * 8)的四舍五入，如果{转换为整数。
do {
numberNine = (int) (Math.random() * 8 + 1);
} while(numberNine == numberEight || numberNine == numberSeven || numberNine == numberSix || numberNine == numberFive || numberNine == numberFour || numberNine == numberThree || numberNine == numberTwo || numberNine == numberOne);
我找到了这样一个错误的引用https://bugs.eclipse.org/bugs/show_bug.cgi?id=482737我不确定问题是否与您的情况相同。
我对您的代码进行了一些修改，这些修改可以成功编译并运行。
public class MagicSquare {
public static void main(String[] args) {
int[][] array = new int[3][3];
fillMatrix(array);
System.out.println("Is magical square:" + isMagicSquare(array));
displayMagicSquare(array);
System.out.println("Is number present:" + isUnique(array, 1));
}
private 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;
}
}
private 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;
}
}
private 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;
}
}
private 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;
}
}
private 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] + "\t");
}
System.out.print("\n");
}
}
private 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 + 2);
} 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;
}
private static boolean isMagicSquare(int[][] array) {
if(sumRows(array) == sumColumns(array) && sumColumns(array) == sumDiagonals(array)) {
return true;
}
else {
return false;
}
}
}