Articles : JavaBoutique's Introduction to Java :
Building Your First Application :

Applet Parameters

There is one more very handy trick that can be performed through HTML. Suppose we wanted to use our Hello applet in a little more generic manner. Instead of simply displaying "Hello Cyberspace", suppose we wanted it to be able to display any phrase determined by the person who codes the HTML.

To do so, we need only make a simple modification to the Hello applet to change it to display some text we define in the HTML instead of having a hard-coded string defined in the code.

Specifically, you can pass parameters to an applet by specifying them in the applet's HTML between the start applet tag and the end applet tag. For example the following HTML passes two parameters to the Hello applet:

<APPLET WIDTH = "200" HEIGHT = "100"
          CODE = "Hello.class">
<PARAM NAME = "text" VALUE = "Have a nice day">
<PARAM NAME = "speed" VALUE = "low">
</APPLET>

The first parameter is named "text" and has a value of "Have a nice day". The second parameter is named "speed" and has a value of "low".

In your applet, you can access these parameters through the getParameter() method. This method is part of the Applet class.

Here we present a modified init() method for the Hello applet which gets the value to display from HTML parameters. In this case, we look for the parameter named "text" and pass the value to the constructor of the Text control:

public void init()
    {
    String text = null;
    try { text = getParameter("text"); }
        catch (Exception e) {}
    if (text == null)
        text = "<No text specified>";
    setLayout(new BorderLayout());
    add(new Text(text), "Center");
    }

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Selena Sol contributes to the JavaBoutique's Introduction to Java. Selena curently works for Barclays Capital in London, one of the leading global investment banks in Europe and has worked as a software developer for the National Center for Human Genome research, Microline Software, Neuron Data, and Electric Eye in Singapore. Selena is perhaps best-known for creating the Public Domain Web Script Archive (Extropia) and writing several books on Web Programming (Perl, CGI, Java).
Email: selena@extropia.com