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How can we call the invokeLater() method in Java?
An invokeLater() method is a static method of the SwingUtilities class and it can be used to perform a task asynchronously in the AWT Event dispatcher thread. The SwingUtilities.invokeLater() method works like SwingUtilities.invokeAndWait() except that it puts the request on the event queue and returns immediately. An invokeLater() method does not wait for the block of code inside the Runnable referred by a target to execute.
Syntax
public static void invokeLater(Runnable target)
Example
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class InvokeLaterTest extends Object {
private static void print(String msg) {
String name = Thread.currentThread().getName();
System.out.println(name + ": " + msg);
}
public static void main(String[] args) {
final JLabel label= new JLabel("Initial text");
JPanel panel = new JPanel(new FlowLayout());
panel.add(label);
JFrame f = new JFrame("InvokeLater Test");
f.setContentPane(panel);
f.setSize(400, 300);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setLocationRelativeTo(null);
f.setVisible(true);
try {
print("sleeping for 5 seconds");
Thread.sleep(5000);
} catch(InterruptedException ie) {
print("interrupted while sleeping");
}
print("creating the code block for an event thread");
Runnable setTextRun = new Runnable() {
public void run() {
try {
Thread.sleep(100);
print("about to do setText()");
label.setText("New text");
} catch(Exception e) {
e.printStackTrace();
}
}
};
print("about to call invokeLater()");
SwingUtilities.invokeLater(setTextRun);
print("back from invokeLater()");
}
}Output
main: sleeping for 5 seconds main: creating the code block for an event thread main: about to call invokeLater() main: back from invokeLater() AWT-EventQueue-0: about to do setText()
Updated on: 02-Jul-2020
2K+ Views
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