Flaw in the Lunar Lander example (IllegalThreadStateException)

问题

I've been playing around with the lunar lander example and have run into a problem while trying to implement an about screen. I changed one of the menu items (in onCreateOptionsMenu) to an "about" option. When this option is selected, a new Activity starts and displays an about screen.

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case MENU_ABOUT:
            startActivity(new Intent(this, About.class));
            return true;
            //Other cases
    }
    return false;
}

This works perfectly and a the focus moves to a new Activity. However, when I press back on the phone to get back to the game, the program crashes. I get this error:

Thread [<3> main] (Suspended (exception IllegalThreadStateException))   
LunarView(SurfaceView).updateWindow(boolean) line: 465  
LunarView(SurfaceView).onWindowVisibilityChanged(int) line: 189 
LunarView(View).dispatchWindowVisibilityChanged(int) line: 3782 
FrameLayout(ViewGroup).dispatchWindowVisibilityChanged(int) line: 704   
FrameLayout(ViewGroup).dispatchWindowVisibilityChanged(int) line: 704   
PhoneWindow$DecorView(ViewGroup).dispatchWindowVisibilityChanged(int) line: 704 
ViewRoot.performTraversals() line: 710  
ViewRoot.handleMessage(Message) line: 1650  
ViewRoot(Handler).dispatchMessage(Message) line: 99 
Looper.loop() line: 123 
ActivityThread.main(String[]) line: 4595    
Method.invokeNative(Object, Object[], Class, Class[], Class, int, boolean) line: not available [native method]  
Method.invoke(Object, Object...) line: 521  
ZygoteInit$MethodAndArgsCaller.run() line: 860  
ZygoteInit.main(String[]) line: 618 
NativeStart.main(String[]) line: not available [native method]

Can anyone help me figure out whats going on? I run into the same problem anytime I try to come back to the game screen from something else (whether its from a preferences Activity, a help Activity, or from the home screen). Thanks

回答1:

The link that fiction gave led me to the answer. The problem wasn't in my code, it was due to a flaw in the Lunar Lander example (it doesn't handle its thread properly).

For anyone looking for a stable game loop that doesn't use Lunar Lander's flawed framework, I found this example to work very well: http://blorb.tumblr.com/post/236799414/simple-java-android-game-loop

Thanks for the help

来源：https://stackoverflow.com/questions/4708198/flaw-in-the-lunar-lander-example-illegalthreadstateexception

标签

android

android-activity

preferences

surfaceview