int rows = 5, column = 7;
int[][] arr = new int[rows][column]; 
   
   //2D arrays are row major, so always row first
   
for (int row = 0; row < arr.length; row++)
{
	for (int col = 0; col < arr[row].length; col++)
    {
    	arr[row][col] = 5; //Whatever value you want to set them to
    }
}

for (double[] row: matrix)
    Arrays.fill(row, 1.0);

int rows = 5, column = 5;