So I'm trying to rotate a line every second using a Timer and a paint method. However, I'm not quite sure whats going on. Here are some of the relevant methods:
public static ActionListener taskPerformer = new ActionListener() {
public void actionPerformed(ActionEvent e) {
Clock cl = new Clock();
seconds++;
cl.repaint();
}
};
public void paint(Graphics g){
super.paint(g);
Graphics2D g2 = (Graphics2D) g;
for(int c = 0; c<10; c++){
g2.setPaint(Color.BLACK);
g2.drawOval(90-c/2,90-c/2,500+c,500+c); //thick outlined circle
}
g2.setPaint(Color.WHITE);
g2.fillOval(90,90,501,501);
g2.setPaint(Color.BLACK);
g2.rotate(Math.toRadians(seconds*6));
g2.drawLine(340,340,340,90);
}
The line remains stationary. However if I add
System.out.println("tick");
to my actionPerformed method, the command line spits out "tick" 3 times a second. Any ideas as to why these things are happening?
Some context:
public static int seconds = 0;
public static int minutes = 0;
public static int hours = 0;
public static Clock cl = new Clock();
private ActionListener taskPerformer = new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.out.println("tick");
seconds++;
cl.repaint();
}
};
public static Timer timer = new Timer(1000,taskPerformer);
public static void main(String[] args){
Clock cl = new Clock();
init();
SwingUtilities.invokeLater(new Runnable(){
public void run() {
createAndShowGUI();
}
});
}
public static void init(){
timer.start();
}
public Clock() {
super("Clock");
timer.addActionListener(taskPerformer);
}
You are creating a new clock at every tick:
public void actionPerformed(ActionEvent e) {
Clock cl = new Clock();
...
Instead you should use an existing instance.
// A field in the class:
Clock cl = new Clock();
...
// removed static so that it can access cl
private ActionListener taskPerformer = new ActionListener() {
public void actionPerformed(ActionEvent e) {
seconds++;
cl.repaint();
}
};
You could also make the clock a field in the action listener, if you do not need to access it elsewhere.
Also note that you generally should not be overriding paint()
, but should override paintComponent()
instead. More about custom painting in swing here.
Edit: Now that there's more code available, it's possible to say that if you make the clock and action listener static it should work. However , you need to start the timer after the relevant components are ready:
public static void main(String[] args){
// Removed spurious clock here
SwingUtilities.invokeLater(new Runnable(){
public void run() {
createAndShowGUI();
// Start the timer once the components are ready
init();
}
});
}
The above mentioned point about not creating a clock in the action listener still stands.
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