Creating an Applet User Interface

Reading System Properties

[Introduce system properties. Refer to tools/system lesson on properties.]

Applets can read some, but not all system properties. This page lists the system properties that Netscape Navigator 2.0 and the Applet Viewer allow applets to read, followed by a list of properties that applets can't read.

System Properties that Applets Can Read

Applets can read the following system properties:

Key			Meaning
-------------------	------------------------------
"java.version"		Java version number
"java.vendor"		Java vendor-specific string
"java.vendor.url"	Java vendor URL
"java.class.version"	Java class version number
"os.name"		Operating system name
"os.arch"		Operating system architecture
"file.separator"	File separator (e.g., "/")
"path.separator"	Path separator (e.g., ":")
"line.separator"	Line separator 

To read a system property from within an applet, the applet uses the System class method getProperty(). For example:

String s = System.getProperty("os.name");

Forbidden System Properties

Applets can not read the following system properties.

Key			Meaning
-------------------	------------------------------
"java.home"		Java installation directory
"java.class.path"	Java classpath
"user.name"		User account name
"user.home"		User home directory
"user.dir"		User's current working directory

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Creating an Applet User Interface