Question

I’m working with Netbeans IDE in Java.

I’ve a form with one JPanel.
Each JPanel has a gridLayout 3×3 and in each place there is an image representing a number[0,1,2,3,4,5,6,7,8](the image is created used a custom class,not just fitting the image in a lab).

I want to be able to exchange two images in the panel when the user click them (First click: no action , second click: switch the two images fitted in the jPanel Components).

I already created a function exchangeComponents and with a test code (like:

exchangeComponents (0,8,jPanel1)

it exchanges correctly the images located in position1 (1st row,1st column) and in position2 (3rd row,3rd column).

The function a creted is the following:

public void exchangeComponents(int component1,int component2,JPanel jpanel){
    try{
   Component aux1 = jpanel.getComponent(component1);
   Point aux1Loc = aux1.getLocation();
   Component aux2 = jpanel.getComponent(component2);
   Point aux2Loc = aux2.getLocation();
   aux1.setLocation(aux2Loc);
   aux2.setLocation(aux1Loc);
   }
   catch (java.lang.ArrayIndexOutOfBoundsException ex){ /* error! bad input to the function*/
       System.exit(1);
   }
}

I suppose I neeed to have an event that call the function exchangeComponents() when the user click on one of the images on the jPanel1 but how should I do it? and how to check what components (images) the user has selected?
I just know that when I create a Button if a click on it (from the IDE) an event like

 private void button1ActionPerformed(java.awt.event.ActionEvent evt) {  
// some code..
}

is created and the code I fill in is executed.

Thank you in advance for any hint.

Answer 1

You need to add the same mouse listener to all you JLabels or whatever container you have for your images, like:

img1.addMouseListener(this);
img2.addMouseListener(this);

etc., then detect which Jlabel you clicked with MouseEvent.getSource(); , like this

boolean hasclicked1=false;
JLabel click1label=null;

public void mouseClicked(MouseEvent me){
  if(!hasclicked1){ //clicked first pic
    hasclicked1 = true;
    click1label = (JLabel) me.getSource();
  } else { //clicked second pic
    hasclicked1 = false;
    exchangeComponents(click1label, (JLabel) me.getSource(), /*your jpanel here*/);
  }
  //now change exchangeComponents so it uses JLabels as parameters
public void exchangeComponents(JLabel component1, JLabel component2, JPanel jpanel){
  try{
    Component aux1 = component1;
    Point aux1Loc = aux1.getLocation();
    Component aux2 = component2;
    Point aux2Loc = aux2.getLocation();
    aux1.setLocation(aux2Loc);
    aux2.setLocation(aux1Loc);
  } catch (java.lang.ArrayIndexOutOfBoundsException ex) { /* error! bad input to the function*/
   System.exit(1);
  }
}

If you are not using JLabels for the images though, replace JLabel in the code with whatever you are using…

EDIT: Sorry, I don’t think I made this unclear, but your class with the method exchangeComponents has to implement MouseListener. Then, in the mouseClicked event put the code I gave for it. Make sure to include the variables hasclicked1 and click1label in your class. Make you class something like this

public class ComponentExchanger implements MouseListener {
boolean hasclicked1=false;
JLabel click1label=null;
JPanel mainPanel;
public ComponentExchanger(){
   //create JFrame, JPanel, etc.
   JFrame f=new JFrame();
   //etc.
   mainPanel=new JPanel();
   f.add(mainPanel);
   //set layout of panel, etc.
   for(int i=0;i<9;i++){
      JLabel l=new JLabel(/*label image here*/);
      Point loc=new Point(/*coordinates here*/);
      l.setLocation(loc);
      mainPanel.add(l);
      /*more code*/
      f.setVisible(true);
   }
}

public static void main(String args[]){
   new ComponentExchanger();
}


public void mouseClicked(MouseEvent me){
  if(!hasclicked1){ //clicked first pic
    hasclicked1 = true;
    click1label = (JLabel) me.getSource();
  } else { //clicked second pic
    hasclicked1 = false;
    exchangeComponents(click1label, (JLabel) me.getSource(), mainPanel);
  }
  //now change exchangeComponents so it uses JLabels as parameters
public void exchangeComponents(JLabel component1, JLabel component2, JPanel jpanel){
  try{
    Component aux1 = component1;
    Point aux1Loc = aux1.getLocation();
    Component aux2 = component2;
    Point aux2Loc = aux2.getLocation();
    aux1.setLocation(aux2Loc);
    aux2.setLocation(aux1Loc);
  } catch (java.lang.ArrayIndexOutOfBoundsException ex) { /* error! bad input to the function*/
   System.exit(1);
  }
}

//Also, you will need to include the other mouselistener implemented methods, just 
//leave them empty
}