public class MainActivity extends AppCompatActivity {  private Button bt;  private TextView tv;  public ProgressDialog myDialog;  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    bt=(Button)findViewById(R.id.button);    tv=(TextView)findViewById(R.id.text);    bt.setOnClickListener(new myOnClickListener());  }  private class myOnClickListener implements View.OnClickListener{    @Override    public void onClick(View v) {      final CharSequence strDialogTitle=getString(R.string.app_about);      final CharSequence strDialogBody=getString(R.string.app_msg);      //顯示對話框      myDialog=ProgressDialog.show(MainActivity.this,strDialogTitle,strDialogBody,true);      tv.setText(R.string.result);      //創建一個空線程模擬運行      new Thread(){        public void run(){          try{            //設置線程睡眠3秒            sleep(3000);          }catch (Exception e){            e.printStackTrace();          }          finally {            //刪除所創建的myDialog對象            myDialog.dismiss();          }        }      }.start();//開始運行線程    }  }}