Calculate Possible Tiles Clicked Unit Can Be Moved On And Display It To Player

Alright, so I'm having problems with lines 11 - 55. I'm trying to calculate the possible tiles the clicked unit can be moved on and display it to the player.

The field is a 9 (columns) by 5 (rows) grid. A unit with can move tiles horizontally or vertically based on its movement.

Example: (unit = o; possible tiles = x) (assuming movement of 2).

[ ][ ][ ][ ][x][ ][ ][ ][ ]
[ ][ ][ ][x][x][x][ ][ ][ ]
[ ][ ][x][x][o][x][x][ ][ ]
[ ][ ][ ][x][x][x][][ ][ ]
[ ][ ][ ][ ][x][ ][ ][ ][ ]

I tried to calculate movement by finding out what column the unit is in, subtracting the column it wants to go to, multiplying the difference by *-1 if the difference is less than 0. Then, doing the same with rows and adding the difference of columns to the difference of rows and comparing it to the unit's movement. Unfortunately, with my code, it seems to move in any directions.

@Override
public void mouseClicked(MouseEvent e) {
if (Main.cards.size() > 0) {
mainloop: for (int i = 0; i < Main.cards.size(); i++) {
Card c = (Card) Main.cards.get(i);
int startingColumn = 0;

[Code] ......