Activity之间的跳转（A-B-A）

Activity   A 中：
Intent intent = new Intent(SubmitAnswerActivity.this,FileActivity.class);
startActivityForResult(intent, 1);

Activity B 中：
Intent intent = new Intent();
intent.putExtra("fileUrl", mFilePath);   //传回给A的东西
setResult(RESULT_OK,intent);

Activity A 中：
再接收B传给A的值
@Override
     protected void onActivityResult(int requestCode, int resultCode, Intent data) {
             // TODO Auto-generated method stub
             if(requestCode==1){
                     if(resultCode==RESULT_OK){
                         String string = data.getStringExtra("fileUrl")；
                     }
             }
     }