AsyncTask开启子线程做事情

onPreExecute doInBackground publishProgress onProgressUpdate onPostExecute
一定得记得调用execute开启任务

new AsyncTask<Void, Void, Void>() {
                
            @Override
            protected void onPreExecute() {
                //主线程
                Toast.makeText(Class2MainActivity.this, "扫描中", 0).show();
                showAnimation();
                super.onPreExecute();
            }
            @Override
            protected Void doInBackground(Void... params) {
                // TODO Auto-generated method stub
                //子线程
                //更新进度
                int count = 100;
                pb.setMax(count);
                for(int i=0;i<count;i++){
                    SystemClock.sleep(50);
                    publishProgress();
                }
                
                return null;
            }
            @Override
            // publishProgress会调用下面的方法 在主线程了
            protected void onProgressUpdate(Void... values) {
                // TODO Auto-generated method stub
                //增加
                pb.incrementProgressBy(1);
                super.onProgressUpdate(values);
            }
            //回到了主线程
            @Override
            protected void onPostExecute(Void result) {
                // TODO Auto-generated method stub
                //停止动画
                iv.clearAnimation();
                Toast.makeText(Class2MainActivity.this, "扫描结束", 0).show();
                super.onPostExecute(result);
            }
        }.execute();