I need a listener that will constantly check if a static boolean value has been changed so that I can repaint a component on a frame. Can someone please help me I really don't know much about listeners and haven't worked with them much? Help will be greatly appreciated.
edit(more clarity): I have two separate classes in which on class is the "main frame" the second class is an extension of JLabel and implements MouseListner for a "clickable photo". The "main frame" creates instances of the photo and when the photo is clicked the "main frame" is supposed to paint on the panel a description of the photo. This is "main frame"
MenuBar menuBar;
static AnnotationVisual a;
Picture pic;
Picture pic2;
GalleryScreen(int rows, int columns){
this.setBorder(BorderFactory.createEmptyBorder(500,500,0,0));
pic = new Picture("pic1", "Z:/My Documents/Downloads/Ball.jpg", new Coordinate(0,0));
pic2 = new Picture("pic2", "Z:/My Documents/Downloads/hoop.jpg" , new Coordinate(1,0));
this.add(pic);
this.add(pic2);
a = new AnnotationVisual();
}
public void paintComponent(Graphics g){
super.paintComponent(g);
if(a.shouldAnnotate()){
FontMetrics size= g.getFontMetrics();
if(getWidth()>=(a.dispX()+size.stringWidth(a.annotationText()))){
g.setColor(Color.white);
g.fillRect(a.dispX()-3,a.dispY()-12,size.stringWidth(a.annotationText())+5,15);
g.setColor(Color.black);
g.drawRect(a.dispX()-3,a.dispY()-12,size.stringWidth(a.annotationText())+5,15);
g.drawString(a.annotationText(), a.dispX(), a.dispY());
}else{
String sub="";
int letters=0;
g.setColor(Color.white);
g.fillRect(a.dispX()-3,a.dispY()-12,getWidth(),15);
g.setColor(Color.black);
for(int i=0;i<a.annotationText().length();i++){
if(a.dispX()+letters+16<=getWidth()){
sub+=a.annotationText().substring(i,i+1);
letters=size.stringWidth(sub);
}else{
sub=sub+"...";
i=a.annotationText().length();
}
}
g.drawRect(a.dispX()-3,a.dispY()-12,size.stringWidth(sub)+3,15);
g.drawString(sub,a.dispX(),a.dispY());
}
}
}
public static AnnotationVisual getA()
{
return a;
}
This is "clickable photo"
import java.awt.Dimension;
import java.awt.Toolkit;
import java.awt.event.*;
import javax.swing.*;
public class Picture extends JLabel implements MouseListener
{
String myAnnotation;
String filePath;
Coordinate imageCoord;
private boolean wasDoubleClick;
private Timer timer;
EditAnnotation newEdit;
AnnotationVisual newVisual;
public Picture(String annotation, String filePath, Coordinate coord)
{
super(new ImageIcon(filePath));
this.addMouseListener(this);
myAnnotation=annotation;
this.filePath = filePath;
imageCoord = coord;
newEdit = new EditAnnotation(annotation);
newVisual = new AnnotationVisual();
}
public Picture(String filePath)
{
super(new ImageIcon(filePath));
this.addMouseListener(this);
this.filePath = filePath;
newEdit = new EditAnnotation();
newVisual = new AnnotationVisual();
}
public String getAnnotation()
{
return myAnnotation;
}
public AnnotationVisual getAnnotationVisual()
{
return newVisual;
}
public void setAnnotation(String annotation)
{
myAnnotation=annotation;
}
public Coordinate getCoordinate()
{
return imageCoord;
}
public void setCoordinate(Coordinate coord)
{
imageCoord = coord;
}
public Dimension getSize()
{
return new Dimension(super.getIcon().getIconWidth(), super.getIcon().getIconHeight());
}
public void mouseClicked(MouseEvent e)
{
final int scrLocX = (int)e.getLocationOnScreen().getX();
final int scrLocY = (int)e.getLocationOnScreen().getY();
if (e.getClickCount() == 2)
{
wasDoubleClick = true;
}
else if(e.getClickCount() == 1)
{
Integer timerinterval = (Integer) Toolkit.getDefaultToolkit().getDesktopProperty("awt.multiClickInterval");
timer = new Timer(timerinterval.intValue(), new ActionListener()
{
public void actionPerformed(ActionEvent evt)
{
if (wasDoubleClick)
{
GalleryScreen.getA().deleteAnnotation();
myAnnotation = newEdit.getAnnotation();
newEdit.show(myAnnotation);
wasDoubleClick = false;
}
else
{
GalleryScreen.getA().deleteAnnotation();
GalleryScreen.getA().showAnnotation(scrLocX, scrLocY , myAnnotation);
}
}
});
timer.setRepeats(false);
timer.start();
}
}
public void mouseEntered(MouseEvent e)
{
}
public void mouseExited(MouseEvent e)
{
}
public void mousePressed(MouseEvent e)
{
}
public void mouseReleased(MouseEvent e)
{
}
}
AnnotationVisual is the thing that supposed to pop up when single clicked
You don't set a listener on a field in Java, you set it on a property. While properties (according to the JavaBeans spec) can be fields, they're usually done as pairs of methods (one getter, one setter; the latter being not needed for read-only fields) as that lets you hook extra logic in to be called when the property is accessed. Such as firing a listener callback to say that the value has changed. (You could use a thread to monitor for that sort of thing, but that's really nasty and error-prone. Wasteful too.)
One thing to be aware of though: you don't know what thread the value will have been modified from. Take care when invoking back into Swing…