1.3.1.1 Creating and Running the Echo Applet

By following the steps on this page, you can create and use a Java applet that echoes a given parameter in the Web page twice.

Create a Java Source File
Compile the Java Code
Create an HTML File that Includes the Applet
View the HTML File

Create a Java Source File

Create a file named EchoApplet.java with the Java code shown here:

import java.applet.Applet;
import java.awt.Graphics;

public class EchoApplet extends Applet {
  String s;

  public void init () {
    s = getParameter("text");
    if (s == null) 
      s = "What, no parameter to echo?";
  }

  public void paint(Graphics g) {
    g.drawString(s, 40, 50);
    g.drawString(s, 40, 70);
  }
}

Compile the Java Code

To compile the source file, you type (under Unix or DOS shell) on the command line:

javac EchoApplet.java

If compilation succeeds, the compiler creates a file named EchoApplet.class. This file contains the bytecodes of your applet, i.e. the code that is suitable for the hypothetical system called Java Virtual Machine to run your program on. If compilation fails, make sure you typed in and named the program exactly as shown above.

Create an HTML File that Includes the Applet

Create a file, say EchoApplet.html in the same directory that contains EchoApplet.class. This HTML file should contain the following text:

<HTML>
<HEAD>
<TITLE>The Echo Applet</TITLE>
</HEAD>
<BODY>

<APPLET CODE="EchoApplet.class" WIDTH=200 HEIGHT=100>
<PARAM name="text" value="Hello Ana and Bob">
</APPLET>

</BODY>
</HTML>

View the HTML File

View the HTML file with a Java-enabled Web browser such as Netscape Navigator, Netscape Communicator, Microsoft Internet Explorer, or HotJava from SUN Microsystems, or with the appletviewer that comes along with Java development environment. In the latter case you enter (under Unix or DOS shell) on the command line

appletviewer EchoApplet.html