Passing pointer position to an object in Java
I've got a JPanel class called Board with a static subclass, MouseHanlder, which tracks the mouse position along the appropriate listener in Board. My Board class has fields pointerX and pointerY.
How do i pass the e.getX() and e.getY() from the MouseHandler subclass to its super class JPanel? I tried with getters, setters, super, and cant get the data transfer between subclass and parent class. I'm certain it's a concept issue, but im stuck.
Thanks!
Due popular demand, some code. This is the code without any atempt of passing :
public class Board extends JPanel {
int x; // Mouse pointer fields.
int y;
public Board() {
blah blah
MouseHandler handler = new MouseHandler();
addMouseMotionListener(handler);
}
static class MouseHandler implements MouseMotionListener {
int pointerX;
int pointerY;
public void mouseMoved(MouseEvent e) {
i'd like to do something like:
开发者_如何学JAVA super.x = e.getX();
super.x = e.getY();
or
Board.setX() = e.getX(); // Missing setters below, this is just an example.
Board.setX() = e.getY();
}
}
}
This because your static implementation of the class doesn't see your jpanel instance. You can do it passing a reference to the MouseAdapter
(or MouseListener
)
class MyPanel extends JPanel
{
MyPanel()
{
item.addMouseListener(new MyListener(this));
}
void pass(int x, int y)
{
//whatever
}
class MyListener extends MouseAdapter
{
MyPanel ref;
MyListener(MyPanel ref)
{
this.ref = ref;
}
public void mousePressed(MouseEvent e)
{
ref.pass(e.getX(), e.getY());
}
}
}
Simple. Do an e.getSource() which will give you the source on which the event occurred. In your case it will be your Board class. Simply cast the instance to a Board instance and you are set.
public class Board extends JPanel {
int x; // Mouse pointer fields.
int y;
public Board() {
blah blah
MouseHandler handler = new MouseHandler();
addMouseMotionListener(handler);
}
static class MouseHandler implements MouseMotionListener {
int pointerX;
int pointerY;
public void mouseMoved(MouseEvent e) {
Board b = (Board) e.getSource();
b.setX(e.getX());
b.setY(e.getY());
}
}
}
Here's one way. This technique uses the implicit reference to the outer class of MouseHandler
:
public class Board extends JPanel {
public Board() {
addMouseListener(new MouseHandler());
}
private void doSomething(int x, int y) {
// ...
}
private final class MouseHandler extends MouseAdapter {
public void mouseMoved(MouseEvent e) {
Board.this.doSomething(e.getX(), e.getY());
}
};
}
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