Question

我正在使用monodroid来制作应用程序。在应用程序中，用户单击一个按钮进入列表视图，该列表视图有多个选项，用户选择选项，然后该选项被发送回原始类，其中textview被更改为与该选项相同的文本。已选中的列表视图。

以下是发送数据的类

 protected override void OnListItemClick(ListView l, View v, int position, long id)
    {
        int t = labels[position];
        String text = t + "";

        Intent send = new Intent(this, typeof(CreateVehicle));
        send.SetFlags(ActivityFlags.ClearTop | ActivityFlags.SingleTop);
        send.PutExtra("t", "Data from FirstActivity");
        StartActivity(send);

    }

以下是接收类：

protected override void OnResume()
    {
        base.OnResume(); // Always call the superclass first.

        TextView tvYearChange = FindViewById<TextView>(Resource.Id.tvYearchange);

        string text = Intent.GetStringExtra("t") ?? "work";

        tvYearChange.SetText(text, null);

    }

如果有人能弄明白为什么我没有收到那些很棒的数据。

Answer 1

我不确定我是否正确解决了您的问题，但我猜您的主要活动是调用具有ListView的活动，然后您希望将结果返回到主活动中，对吗？

如果是这样，您显示的代码不是您想要的正确方法。您要找的是在主要活动中使用StartActivityForResult并覆盖onActivityResult方法。

我不确切知道如何使用Monodroid和C＃，但我可以用Java给你一个例子，我相信它会帮助你理解如何得到你想要的东西：

假设我的ListView活动名为 myList 并扩展了ListActivity，我的主要活动称为 MainActivity 。下面是 myList 的OnListItemClick方法：

@Override
protected void onListItemClick(ListView l, View v, int position, long id){
    super.onListItemClick(l, v, position, id);

    String text = String.valueOf(labels[position]);

    // Create the intent with the extras
    Intent send = new Intent();
    send.putExtra("text_from_list", text);

    // Set the result to OK (meaning the extras are put as expected by the caller)
    setResult(RESULT_OK, send);
      // you need this so the caller (MainActivity) knows that the user completed
      // this activity (myList) as expected (clicking on the item to return a result)
      // and didn't just leave the activity (back button)

    // Close this List Activity
    finish();
}

以下是我的主要活动中调用myList的方法：

private void callListActivity(){
    Intent call = new Intent(MainActivity.this, myList.class);
    startActivityForResult(call, 1);    
      // The second field is just a number to identify which activity 
      // returned a result when a result is received (you can have 
      // several calls to different activities expecting results from
      // each one of them). This number is called requestCode.
}

您必须使用以下内容覆盖 MainActivity 中的onActivityResult：

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    // Check if the returned data came from myList (requestCode 1) and if
    // data was actually received (check if resultCode = RESULT_OK)
    if (requestCode == 1) { 
        if (resultCode == RESULT_OK) {
            String text = data.getStringExtra("text_from_list");
              // you have to use the same string identifier you used
              // when you put the extra in the Intent in myList

            TextView tvYearChange = (TextView)findViewById(R.id.tvYearchange);

            tvYearChange.setText(text);
        }
        else {
            // Do something if the Activity didn't return data
            // (resultCode != RESULT_OK)
        }
    }

    // If you are expecting results from other Activities put more if
    // clauses here with the appropriate request code, for example:
    // if (requestCode == 2) {
    //     DoSomething;
    // }
    // And so on...
}

将此Java代码修改为可以与Monodroid一起使用的C＃代码应该不难。另外，请查看Android官方文档中的this link，它们在那里有很多有用的东西。

我希望这会对你有所帮助。

Answer 2

在Receiver Activity中从intent获取数据，如下所示

Intent intent = getIntent();
string text = intent.getStringExtra("t");

无法从意图中接收数据

2 个答案: