Question

How to prevent other classes changing the System.out? I would like to set the System.out PrintStream in App.main and make it a final so it can’t be changed anymore form the other parts of the App. Is it possible? Any hacky way would do 🙂

Answer 1

I quick look at the code shows the SecurityManager can be used to prevent changes. 😉

public static void setErr(PrintStream err) {
    checkIO();
    setErr0(err);
}

private static void checkIO() {
    SecurityManager sm = getSecurityManager();
    if (sm != null) {
        sm.checkPermission(new RuntimePermission("setIO"));
    }
}

You can use Thread.currentThread().getStackTrace() to identify the caller.