【Android】ActionBar最左邊返回鍵

private ActionBar mActionBar;

mActionBar = getSupportActionBar();

mActionBar.setDisplayShowHomeEnabled(true);   //顯示返回符號，在android 2.3測試，若setDis                                                  //playHomeAsUpEnabled沒寫，則無任何動作發生

mActionBar.setDisplayHomeAsUpEnabled(true);   //不顯示返回符號，在onOptionsItemSelected須設定                                              //按下後動作
mActionBar.setTitle("Title ");

@Override
public boolean onOptionsItemSelected(MenuItem item) {
 switch (item.getItemId()) {
 case android.R.id.home:
 // app icon in action bar clicked; goto parent activity.
  onBackPressed();
  return true;
   ...

}

}

-----------------------------------------

//可改寫返回鍵的內容設定

@Override
public void onBackPressed() {
 Intent intent = new Intent(this, MainActivity.class);
 intent.putExtra("test", "i am come from Mainactivity2activity");
 setResult(RESULT_OK, intent);
 
 closeDB();
 finish();
}