Как найти количество столбцов в массиве

It’s important to understand that Java doesn’t really have two-dimensional arrays. It has arrays of arrays. That means, for instance, that you can have this:

int[][] array=
{
    {1},
    {1, 2, 3},
    {1, 2, 3, 4, 5},
    {1, 2}
};

So there is no one upper bound of the second level. Java arrays are inherently jagged, each of the second level in the above has its own length.

So to loop them correctly, you have to check for each of the second-level arrays:

int x, y;
int[] second;

for (x = 0; x < array.length; ++x) {
    second = array[x];
    for (y = 0; y < second.length; ++y) {
         // ....
    }
}

Full example: Live Copy

public class ArrayExample {
    public static void main(String[] args) {
        int[][] array=
        {
            {1},
            {1, 2, 3},
            {1, 2, 3, 4, 5},
            {1, 2}
        };
        int x, y;
        int[] second;

        for (x = 0; x < array.length; ++x) {
          second = array[x];
          for (y = 0; y < second.length; ++y) {
              System.out.println(x + "," + y + ": " + second[y]);
          }
          System.out.println();
        }
    }
}

Output:

0,0: 1

1,0: 1
1,1: 2
1,2: 3

2,0: 1
2,1: 2
2,2: 3
2,3: 4
2,4: 5

3,0: 1
3,1: 2

Or if you don’t need the indexes, just the values, you can use the enhanced for loop: Live Example

public class ArrayExample {
    public static void main(String[] args) {
        int[][] array=
        {
            {1},
            {1, 2, 3},
            {1, 2, 3, 4, 5},
            {1, 2}
        };

        for (int[] second : array) {
          for (int entry : second) {
              System.out.println(entry);
          }
          System.out.println();
        }
    }
}

Output:

1

1
2
3

1
2
3
4
5

1
2