Using ActionListener to swap two icons in a grid

Question

I'm trying to move a piece from one square in a grid to another by clicking first on the piece and then clicking on the square to move it too.

How can I save the location of the first icon, and then swap it with the second?

At the moment I'm looking at this code which simply moves the piece one square left:

public void actionPerformed(ActionEvent e)  
{
for ( x=0; x<8; x++)
        for( y=0; y<8; y++) {
        if(e.getSource() == board[x][y])
        ((ChessSquare)e.getSource()).swap(board[x][y-1]);
    }
}

Andrew Thompson · Answer 1 · 2013-03-18T18:26:27.923

1

Store a flag indicating whether this is a 'drag' or 'drop'¹.
If 'drag' store the original co-ordinates and change the flag to 'drop'.
If 'drop' read the co-ordinates of the source, use them as you will and set the flag back to 'drag'.

By that I mean something like declaring a boolean drag and setting it true/false as needed.

..best place to store the coordinates?

I'd use 2 int attributes, though if you wanted to misuse a Dimension object, just one could store both x & y co-ords.

..No, scrap that. Using the client properties as indicated by mKorbel seems a lot more 'neat'.

edited Mar 18 '13 at 18:26

answered Mar 18 '13 at 17:51

Andrew Thompson

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Where would be the best place to store the coordinates? – user2079483 Mar 18 '13 at 17:58
1

probably [putClientProperty](http://stackoverflow.com/a/10385302/714968) is easiest of the ways, sure ...., maybe not – mKorbel Mar 18 '13 at 18:21
1

@mKorbel Huh, ..neat! The things in the docs I've missed. :) – Andrew Thompson Mar 18 '13 at 18:25

VishalDevgire · Answer 2 · 2013-03-18T18:05:02.697

We'll need a Boolean flag which will keep track of 'click'

if flag = false it's first click otherwise it's second click (this is where we'll perform swap).

public void actionPerformed(ActionEvent e)  
{
    int xPos1,xPos2,yPos1,yPos2;
    if(!flag)
    {
      for ( x=0; x<8; x++)
      {
          for( y=0; y<8; y++) 
          {
            if(e.getSource() == board[x][y])
            {
              xPos1 = x; // Source icon cordinates.
              yPos2 = y;
              break;
            }
          }
      }
      flag = true;
    }
    else
    {
      for ( x=0; x<8; x++)
      {
        for( y=0; y<8; y++) 
        {
          if(e.getSource() == board[x][y])
          {
            xPos2 = x;  // Target icon cordinates.
            yPos2 = y;
            break;
          }
        }
      }

      // Swapping code add your version of this swapping code here.
      // Swap source with target.
      Icon temp = board[xPos1][yPos1]
      board[xPos1][yPos1] = board[xPos2][yPos2];
      board[xPos2][yPos2] = temp;          
      // ----------------- End Swap----------------  

      flag = false; // ready for next swap operation.
  }

}

should very complicated, see code in my comment to another question here, — mKorbel, Mar 18 '13 at 18:22

Using ActionListener to swap two icons in a grid

2 Answers2