java - java.lang.ArrayIndexOutOfBoundsException : 问题

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What causes a java.lang.ArrayIndexOutOfBoundsException and how do I prevent it? (25 个回答)

已关闭 7 年前。

我正在尝试计算 2D 数组的行和列总和，但总是收到此错误 java.lang.ArrayIndexOutOfBoundsException: 2

它说computeRowSums方法中有一个错误，但我无法弄清楚为什么它会是数组索引越界。

// RowColSums.java
// To compute the row and column sums of a 2D array.
import java.util.*;

public class RowColSums {

    public static void main(String[] args) {

        int row_size, col_size, row, col;
        int[][] array2D;

        Scanner sc = new Scanner(System.in);

        System.out.println("Enter number of rows and columns: ");
        row_size = sc.nextInt();
        col_size = sc.nextInt();

        array2D = new int[row_size][col_size];

        System.out.println("Enter values for 2D array: ");
        for(row = 0; row < row_size; row++)
            for(col = 0; col < col_size; col++)
                array2D[row][col] = sc.nextInt();

        int[] rowSums = computeRowSums(array2D);
        System.out.print("Row sums: ");
        System.out.println(Arrays.toString(rowSums));

        int[] colSums = computeColSums(array2D);
        System.out.print("Column sums: ");
        System.out.println(Arrays.toString(colSums));
    }

    public static int[] computeRowSums(int[][] arr)
    {
        int i, j; 
        int[] row_sum = new int[arr[0].length];

        for(i = 0; i < arr[0].length; i++) 
            for(j = 0; j < arr.length; j++)
                row_sum[i] += arr[i][j];

        return row_sum;

    }
    public static int[] computeColSums(int[][] arr)
    {
        int z, r;
        int[] col_sum = new int[arr.length];

        for(z = 0; z < arr.length; z++)
            for(r = 0; r < arr[0].length; r++)
                col_sum[z] += arr[z][r];

        return col_sum;
    }
}

Answer 1

在computeRowSums中，您得到的索引顺序错误。应该是:

    for(i = 0; i < arr[0].length; i++) 
        for(j = 0; j < arr.length; j++)
            row_sum[i] += arr[j][i];

我假设您的二维数组具有不同的行数和列数，这解释了您遇到的异常。