public boolean validateInput()
	{
		int i = 0, j = 0;
		for(i = 0; i < 9; i++)
		{
			for(j = 0; j < 9; j++)
			{
				    try 
				    {
				    	
				        if(Integer.parseInt(entries[i][j].getText()) < 1)
				        {
				        	return false;
				        }
				    }
				    catch (NumberFormatException e) 
				    {
				        JOptionPane.showMessageDialog(null, "Invalid input. Enter an integer at row " + (i+1) + " column " + (j+1), "Error", JOptionPane.ERROR_MESSAGE);
				        return false;
				    }
			}
		}
		return true;
	}