public void start() { 
     label0: { 
            synchronized(running) { 
                if(!running.booleanValue()) 
                    break label0; 
                position = 0; 
                repeatsLeft = repeatCount; 
            } 
            return; 
        } 
     
     animationThread = new Thread(new Runnable() {             public void run() { 
                runAnimation(); 
            } 
        }); 
     
        animationThread.start(); 
        running = Boolean.valueOf(true); 
        boolean1; 
        JVM INSTR monitorexit ; 
    } 
我知道好像是个反编译。 
1.提问:label0作用?最后两行的作用?