java - 错误消息 Exception in thread "main"java.lang.ArrayIndexOutOfBoundsException :

Question

我有此代码，但我不断收到此错误消息，我不知道为什么？

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 2 at javaapplication28.JavaApplication28.main(JavaApplication28.java:38) 1 2 Java Result: 1

public static void main(String[] args) {   

    Scanner input = new Scanner(System.in);
        System.out.println("This program transposes a matrix.");
        System.out.println("Please enter the number of rows");
        int rows = input.nextInt();
        System.out.println("User enters: "+rows);
        System.out.println("Please enter the number of columns");
        int columns = input.nextInt();
        System.out.println("User enters: "+columns);
        int [][]matrix=new int[rows][columns];
        for(int i=0;i<matrix.length;i++){
            for(int j=0;j<matrix[i].length;j++){
             System.out.print("Enter value for row [" +i+ "] column [" +j+"]:");
                matrix[i][j]=input.nextInt();  
            }
        }
        for(int i=0;i<=matrix.length;i++){
             System.out.println();
             for(int j=0;j<=matrix.length;j++){
                 System.out.print(matrix[i][j]+"  ");           
             }
         }
        System.out.println("The transpose of this matrix has" +columns+"rows and"+rows+"columns and the transpose is:");
        for(int i=0;i<=matrix.length;i++){
             System.out.println();
             for(int j=0;j<=matrix.length;j++){
                 System.out.print(matrix[j][i]+"  ");
    }
}}
}

Answer 1

你在从 0 到 length+1 的循环中运行 i<=matrix.length .删除 =来自 for语句和内部循环添加:matrix[i].length相反 matrix.length获取列数而不是行数。

这里是有效代码:

for(int i=0;i<matrix.length;i++){
        System.out.println();
        for(int j=0;j<matrix[i].length;j++){
            System.out.print(matrix[i][j]+"  ");           
        }
    }
    System.out.println("The transpose of this matrix has" +columns+"rows and"+rows+"columns and the transpose is:");
    for(int i=0;i<matrix.length;i++){
        System.out.println();
        for(int j=0;j<matrix[i].length;j++){
            System.out.print(matrix[j][i]+"  ");
        }
    }}