how can I run javaw in windows XP cmd?

Question

I made a program using JAVA.

I export the java project as runnable jar file.

I tested it in Windows 7 32bit.

It runs perfectly.

However, when I tested it in windows xp 32bit(I'm not sure about it's SP version. maybe SP2 or SP3)

It shows error message "cannot access to C:\my.jar"

I did googling, and found that

Windows 7 and XP have different function to load javaw

However... I don't know the exact way to run javaw in Windows XP

How can I run it?

Here is the code with "Cannot access" error

public void RunApplication() {
    try {
        Runtime.getRuntime().exec("javaw -jar " + PROGRAM_PATH + "/Client.jar");
    } catch (IOException ioe) {
        ioe.printStackTrace();
    }
}

And here is another code.

If I run this, Windows XP doens't show anything. No error, No application.

public void RunApplication() {
    try {
        Runtime.getRuntime().exec("start javaw -jar " + PROGRAM_PATH + "/Client.jar");
    } catch (IOException ioe) {
        ioe.printStackTrace();
    }
}