如何在Java中复制具有未知列大小的二维数组？

Question

For school work I need to write a constructor for a class that contains a 2-dimensional array of integers. The constructor copies a passed in two-dimensional array. Below is the code I have so far. The current issue I have is how to initialize the array when the "column" size of the passed in array is unknow. The issue I think I am having is when creating and initializing the array. The length of the inner and out array is unknown.

 public IntMatrix (int[][] array)
    {_matrix = new int [array.length][array.length-1].length];
    for (int i = 0; i < array.length; i++) {
        for(int j=0; j < array[i].length; j++)
        _matrix[i][j]=array[i][j];
    }
}

Answer 1

As I said in a comment, what you have is an array of arrays:

public IntMatrix(int[][] array) {
    matrix = new int[array.length][];
    for (int i = 0; i < array.length; i++) {
        matrix[i] = new int[array[i].length];
        for(int j=0; j < array[i].length; j++) {
            matrix[i][j] = array[i][j];
        }
    }
}

Answer 2

You can always determine the size of an array via myArray.length , so you can allocate for each row/column as you iterate through.

A thought, however. Is it acceptable to simply store the reference to the array that you're passed ? Will it change outside your class ? If not, then that might be a simple solution if you don't have to recreate the array internally.