File.createTempFile()

java.lang.NoSuchMethodError: java/io/File: method
createTempFile(Ljava/lang/String;Ljava/lang/String;)Ljava/io/File; not
found.

Answer:
The latest version of Java supported by Microsoft Internet Explorer and Netscape Navigator/Communicator is JDK 1.1.x. File.createTempFile() is not present in JDK 1.1 and was only just added in JDK 1.2 as part of the Java 2 Platform Specification.

You will need to use a Java 2 Plugin if you want to use JDK 1.2 features in applets. However, you will run into problems with the security manager because applets are generally not allowed to access the local file system. You will have to familiarize yourself with the permissions APIs specific to each browser to bypass this restriction.