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| Listening for Scrollbar Value Changes in a JScrollPane Container |
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import java.awt.Adjustable;
import java.awt.event.AdjustmentEvent;
import java.awt.event.AdjustmentListener;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
public class Main {
public static void main(String[] argv) throws Exception {
JTextArea textArea = new JTextArea();
JScrollPane pane = new JScrollPane(textArea);
// Listen for value changes in the scroll pane's scrollbars
AdjustmentListener listener = new MyAdjustmentListener();
pane.getHorizontalScrollBar().addAdjustmentListener(listener);
pane.getVerticalScrollBar().addAdjustmentListener(listener);
}
}
class MyAdjustmentListener implements AdjustmentListener {
public void adjustmentValueChanged(AdjustmentEvent evt) {
Adjustable source = evt.getAdjustable();
if (evt.getValueIsAdjusting()) {
return;
}
int orient = source.getOrientation();
if (orient == Adjustable.HORIZONTAL) {
System.out.println("from horizontal scrollbar");
} else {
System.out.println("from vertical scrollbar");
}
int type = evt.getAdjustmentType();
switch (type) {
case AdjustmentEvent.UNIT_INCREMENT:
System.out.println("Scrollbar was increased by one unit");
break;
case AdjustmentEvent.UNIT_DECREMENT:
System.out.println("Scrollbar was decreased by one unit");
break;
case AdjustmentEvent.BLOCK_INCREMENT:
System.out.println("Scrollbar was increased by one block");
break;
case AdjustmentEvent.BLOCK_DECREMENT:
System.out.println("Scrollbar was decreased by one block");
break;
case AdjustmentEvent.TRACK:
System.out.println("The knob on the scrollbar was dragged");
break;
}
int value = evt.getValue();
}
}
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