Question:
How do you change a button’s caption after it is created?
Answer:
Java’s Button class defines two methods for getting and setting a button’s caption. They are getLabel() and setLabel(). The following simple applet creates a button whose caption changes when the user presses the button:
import java.awt.*;import java.applet.*; public class ButtonLabel extends Applet { Button b; boolean active = false; // define a button with some initial label public void init() { b = new Button(“Inactive”); add(b); } // Change the caption when the user presses the button // after it has been created public synchronized boolean handleEvent(Event e) { if (e.target instanceof Button) { if (active) { active = false; b.setLabel(“Inactive”); } else { active = true; b.setLabel(“Active”); } return true; } return false; } // // Defining a main() routine allows the applet to be // run as a standalone Java application also // public static void main(String argv[]) { Frame f = new Frame(“ButtonLabel”); Applet a = new ButtonLabel(); a.init(); a.start(); f.setLayout(new BorderLayout()); f.add(“Center”, a); f.pack(); f.show(); }}
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