Writing the Code to Support Parameters - Java Tutorial 5.0 英文版

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Writing the Code to Support Parameters

Applets use the Applet getParameter method to get user-specified values for applet parameters. The getParameter method is defined as follows:

public String getParameter(String name)

Your applet might need to convert the string that getParameter returns into another form, such as an integer. The java.lang package provides classes such as Integer that you can use to help with converting strings to primitive types. Here's an example of converting a parameter's value into an integer:

int requestedWidth = 0;
. . .
String windowWidthString = getParameter("WINDOWWIDTH");
if (windowWidthString != null) {
    try {
        requestedWidth = Integer.parseInt(windowWidthString);
    } catch (NumberFormatException e) {
        //Use default width.
    }
}

Note that if the user doesn't specify a value for the WINDOWWIDTH parameter, the above code uses a default value of 0, which the applet interprets as "use the window's natural size." It's important that you supply default values wherever possible.

Besides using the getParameter method to get values of applet-specific parameters, you can also use getParameter to get the values of attributes of the applet's <APPLET> tag. See Using the applet Tag for a list of <APPLET> tag attributes.

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