public class MainActivity extends AppCompatActivity {static Activity activity;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);CommUtil commUtil = CommUtil.getInstance(this);}

public class CommUtils {private static CommUtils instance;private Context context;private CommUtils(Context context) {this.context = context;}public static CommUtils getInstance(Context context) {if (instance == null) {instance = new CommUtils(context);}return instance;}
}

protected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);new AsyncTask<String, Void, String>() {@Overrideprotected String doInBackground(String... params) {for (int i = 0; i < 15; i++) {try {Log.e("MainActivity2", "dddd" + i + MainActivity2.this.getLocalClassName());Thread.sleep(1000);} catch (InterruptedException e) {e.printStackTrace();}}return null;}@Overrideprotected void onPostExecute(String s) {super.onPostExecute(s);}}.execute();}

 MyHandler myHandler = new MyHandler();@Overrideprotected void onCreate(@Nullable Bundle savedInstanceState) {super.onCreate(savedInstanceState);myHandler.postDelayed(new Runnable() {@Overridepublic void run() {}}, 50 * 1000);}class MyHandler extends Handler {@Overridepublic void handleMessage(Message msg) {super.handleMessage(msg);}}

static MyHandler myHandler;@Overrideprotected void onCreate(@Nullable Bundle savedInstanceState) {super.onCreate(savedInstanceState);myHandler = new MyHandler(this);}static class MyHandler extends Handler {WeakReference<Activity> mActivityReference;MyHandler(Activity activity) {mActivityReference = new WeakReference<Activity>(activity);}@Overridepublic void handleMessage(Message msg) {final Activity activity = mActivityReference.get();if (activity != null) {//....}}}

public class DemoActivity extends AppCompatActivity {Runnable runnable = new Runnable() {@Overridepublic void run() {}};

public View getView(int position, View convertView, ViewGroup parent) {View view = null;if (convertView == null)convertView = View.inflate(this, R.layout.item_layout, false);view = convertView;return view;}

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