Miscellaneous I

Answer: Spawn a thread that knows about the parent Window, and every X

milliseconds, executes the toFront () command of that window. Just remember to

execute it using SwingUtilities.invokeLater (), and don t

let your users launch two apps, unless you enjoy screen lockup.

Can a java application be run of a CD without installing anything (i.e. runtime, etc)

on the target computer?

I would like to put my application and hand it out as a demo, but I want to make it

easy to view.

Answer1: by 

Dale King

  The JRE was made so that it didn t need to be "installed".

What I did in one case was to simply put the JRE into a jre folder in the same

directory as my application then invoke it from that directory using:

jre\bin\jre.exe  cp MyJar.java MyClass

That was for JDK1.1 and you have to modify it slightly for Java 2. But this did not

require any installation of environment variables to be set up. The JRE was smart

enough to know how to get to its system classes relative to where the jre.exe file was

located.

Answer2: you could try a Java to native compiler.

 I would like to know whether it is possible to test the memory, so as to avoid the

OutOfMemoryError or whether it is possible to increase the amount of memory in the

JRM.

Answer: You can get the total and available memory used by the VM by making two

calls from the Runtime class:

   Runtime runtime = Runtime.getRuntime();

   long free = runtime.freeMemory(); //the available memory

   long total = runtime.totalMemory(); // the total for the JVM

The amount returned be totalMemory() isn t that useful unless you specify how much

memory your program will have from the beginning (if you don t, the JVM will just

keep grabbing more until you run out). 

You can set the initial and maximum memory from the command line:

java  Xms64m  Xmx64m name.of.Application

This will start your appplication with 64 megs initial and maximum memory.

Corey Wineman

What needs to be done to reduce size of a jar file? What optimization techniques

to use on classes inside the jar file? What tools if any?

Answer: A JAR file is a ZIP archive. You can influence its size by choosing the

degree of compression you want to have. This is usually defined by a value between

0 (no compression) and 9 (maximum compression). Although JAR tool does not list a

 9 switch, you might want to create compressed JARs with any ZIP tool like Winzip or

the free Info ZIP zip command line tool. 

The amount of reduction you get totally depends on the nature of your data. 

Note that if you use compression in your JAR file, loading goes slower (classes must

be decompressed).

Q: Is there any way to run code after the VM has been instructed to exit?

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