Intent里可以设置Flag，比如FLAG_ACTIVITY_BROUGHT_TO_FRONT。
以下的例子简单说明了Flag的用法.
FirstActivity:
1. public class RecordActivity extends Activity {
2. /** Called when the activity is first created. */
3. @Override
4. public void onCreate(Bundle savedInstanceState) {
5. super.onCreate(savedInstanceState);
6. setContentView(R.layout.first);
7.
8. Button goSecond = (Button)findViewById(R.id.go_to_second);
9. goSecond.setOnClickListener(mGoSecond);
10. }
11.
12. private OnClickListener mGoSecond = new OnClickListener(){
13. public void onClick(View v){
14. new Intent(RecordActivity.this, SecondActivity.class);
15. startActivity(i);
16. }
17. };
18. }
secondActivity:
1. public class SecondActivity extends Activity {
2. @Override
3. protected void onCreate(Bundle savedInstanceState) {
4. // TODO Auto-generated method stub
5. super.onCreate(savedInstanceState);
6.
7. setContentView(R.layout.second);
8.
9. Button goThird = (Button)findViewById(R.id.go_to_third);
10. goThird.setOnClickListener(mGoThird);
11. }
12.
13. private OnClickListener mGoThird = new OnClickListener(){
14. public void onClick(View v){
15. new Intent(SecondActivity.this, ThirdActivity.class);
16. startActivity(i);
17. }
18. };
19. }
thirdAcitivity:
1. public class ThirdActivity extends Activity {
2. @Override
3. protected void onCreate(Bundle savedInstanceState) {
4. // TODO Auto-generated method stub
5. super.onCreate(savedInstanceState);
6.
7. setContentView(R.layout.third);
8.
9. Button goForth = (Button)findViewById(R.id.go_to_forth);
10. goForth.setOnClickListener(mGoForth);
11. }
12.
13. private OnClickListener mGoForth = new OnClickListener(){
14. public void onClick(View v){
15. new Intent(ThirdActivity.this, ForthActivity.class);
16. startActivity(i);
17. }
18. };
19. }forthActivity:
1. public class ForthActivity extends Activity {
2. @Override
3. protected void onCreate(Bundle savedInstanceState) {
4. // TODO Auto-generated method stub
5. super.onCreate(savedInstanceState);
6.
7. setContentView(R.layout.forth);
8.
9. Button recordSecond = (Button)findViewById(R.id.forth);
10. recordSecond.setOnClickListener(mRecord);
11. }
12.
13. private OnClickListener mRecord = new OnClickListener(){
14. public void onClick(View v){
15. new Intent(ForthActivity.this, SecondActivity.class);
16. i.addFlags(Intent.FLAG_ACTIVITY_BROUGHT_TO_FRONT);
17. startActivity(i);
18. }
19. };
20. }
