importandroid.app.Activity;importandroid.os.Bundle;importandroid.os.Handler;importandroid.view.Menu;importandroid.view.MenuItem;importandroid.view.View;importandroid.widget.TextView;publicclassMainActivityextendsActivity{TextViewtextView;Handlerhandler;Runnablerunnable;booleanstop=true;@OverrideprotectedvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);textView=(TextView)findViewById(R.id.text);handler=newHandler();runnable=newRunnable(){@Overridepublicvoidrun(){inta=(int)(Math.random()*10);textView.setText(a+"");handler.postDelayed(runnable,50);}};}publicvoidstart(Viewview){if(stop){handler.postDelayed(runnable,0);stop=!stop;}else{handler.removeCallbacks(runnable);stop=!stop;}}}