1 public class MainActivity extends AppCompatActivity {
 2 
 3     private TextView tv;
 4     @Override
 5     protected void onCreate(Bundle savedInstanceState) {
 6         super.onCreate(savedInstanceState);
 7         setContentView(R.layout.activity_main);
 8 
 9         tv= (TextView) findViewById(R.id.tv);
10 
11         tv.setText(String.format("TaskId:%d\nCurrent Activity ID:%s",getTaskId(),toString()));
12         findViewById(R.id.btn).setOnClickListener(new View.OnClickListener() {
13             @Override
14             public void onClick(View v) {
15                 startActivity(new Intent(MainActivity.this,MainActivity.class));
16             }
17         });
18     }
19 
20 }