I'm trying to create a small GUI, it has 2 JButtons, and 2 JPanels with some drawing animation on each of them. By default it must show first JPanel, and by clicking on second JButton I want to see my second JPanel. So : I create JFrame, Panel1 and Panel2, where I have drawn my animations, create Button1 and Button2 and adding to them ActionListeners. I have also MainPanel which has in a fields variable i. By changing this "i" my constructor adds to MainPanel either Panel1 (default) or Panel2 (by clicking on JButton2 I change i). Than I add this MainPanel to my frame. So my question : in the class MainPanel I have refreshMe method, what should I write there to make my GUI working properly? Thanks. Here is my code:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class GuiTest {
public static void main(String[] args) {
JFrame f = new JFrame();
MainPanel myPanel = new MainPanel();
f.add(myPanel);
Button1 button1 = new Button1();
Button2 button2 = new Button2();
myPanel.add(button1);
myPanel.add(button2);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.pack();
f.setVisible(true);
}
}
class MainPanel extends JPanel {
Panel1 p1 = new Panel1();
Panel2 p2 = new Panel2();
public int i = 1; //this is being changed later by clicking JButton
// I use this setter later in actionPerformed in order to change i
public void setI(int i) {
this.i = i;
}
MainPanel() {
if (i == 1) {
this.add(p1);
}
if (i == 2) {
this.add(p2);
}
}
public void refreshMe() {
// Need some help here:
// I don't know what should I write, how to make a repaint of myPanel?
System.out.println("just test, if the method refreshMe working by clicking some button");
}
}
class Panel1 extends JPanel {
public Panel1() {
this.setBackground(Color.BLUE);
// a lot of drawing stuff going on here
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
}
class Panel2 extends JPanel {
public Panel2() {
this.setBackground(Color.GREEN);
// a lot of drawing stuff going on here
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
}
class Button1 extends JButton {
MainPanel someObj1 = new MainPanel();
Button1() {
setText("Show Annimation A");
addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
someObj1.setI(1);
System.out.println("The variable i is now: " + someObj1.i);
someObj1.refreshMe();
}
});
}
}
class Button2 extends JButton {
MainPanel someObj2 = new MainPanel();
Button2() {
setText("Show Annimation B");
addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
someObj2.setI(2);
System.out.println("The variable i is now: " + someObj2.i);
someObj2.refreshMe();
}
});
}
}
Best Answer
In order to reflect changes after adding/removing or resizing a component that is on a visible container call
revalidate()
andrepaint()
on the containers instance after adding/removing or resizing the component.Though this will not work in your code the main reason being inside JButton classes you recreate a new instance of
MainPanel
when in fact the 2JButtons
should share the single instance which is being used (you could pass MainPanel instance to theJButton
s constructors, but you shouldn't really be extending aJButton
unless adding custom functionality):A few other suggestions on your code:
Dont extend
JButton
class unnecessarily, simply create an instance ofJButton
like you did withJFrame
and call methods onJButton
instance.Dont forget to create/manipulate Swing components on
Event Dispatch Thread
, viaSwingUtilities.invokeLater(..)
block, read here for more.Here is your code fixed (above suggestions ect implemented):
However Id suggest something simpler, fortunately you have 2 choices:
1) Use
CardLayout
which will allow you to flip between multiple components on a singleJFrame
/container.Here is an example I made:
2) Use
removeAll()
technique i.e callframe.getContentPane().removeAll()
which will remove all components currently onJFrame
and than add the new content and callrevalidate()
andrepaint()
(also might want to addpack()
in there) onJFrame
instance to reflect changes. Though Id recommendCardLayout
.