java如何与来自不同类的UI交互

Question

我想从其他类更新我的UI。我熟悉runOnUiThread()方法，但不知道如何在这个场景中实现它

public class UploadAct extends MainActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_upload);
    }

    //my code and functions would go here
}

然后，我的UploadData类

public class UploadData extends UploadAct {
    public void doSomethig(){
        printThis("I want to print this message to the UI");
    }

    public void printThis(String messsage) {
        final String mess = message;
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                Toast.makeText(getApplicationContext(),mess,Toast.LENGTH_LONG).show();
                // I want this to display on the main thread
                txt_upload.setText(mess);// and this also
        }
    });
}

}

Answer 1

每个人都会使用太多的库来成为时尚，因为他们忘记了Android中的内置功能：）

当然，使用AsyncTask并不难，除了它提供了doInBackground函数之外，它还提供了https://developer.android.com/reference/android/os/AsyncTask.html#publishProgress(Progress...)函数，这是您所要求的

只需创建一个类（UploadTask），它扩展AsyncTask并重写1-2函数

Answer 2

首先，没有像某个类的UI这样的东西。有些活动可以处理UI小部件（例如TextView）。如果您想从UploadData类对UI进行一些更改，您必须以某种方式传递对该类的引用。可能由建造商：

public class UploadData extends UploadAct{
private TextView txt_upload;

public UploadData(TextView tv)
{
      txt_upload = tv;
}
public void doSomethig(){
printThis("I want to print this message to the UI")
}

 public void printThis(String messsage) {
    final String mess = message;
    runOnUiThread(new Runnable() {
        @Override
        public void run() {
                       Toast.makeText(getApplicationContext(),mess,Toast.LENGTH_LONG).show();// I want this to display on the main thread
            txt_upload.setText(mess);// and this also
        }
    });
}
}

我假设您在MainActivity中创建了DataUpload

Answer 3

使用BroadcastReceiver

// define a Broadcast Intent Action in String resources
<string name="broadcast_id">MY_BROADCAST_ID</string>

// register receiver in constructor/onCreate()
MyBroadcastReceiver myBroadcastReceiver = new MyBroadcastReceiver();
IntentFilter myIntentFilter = new IntentFilter();
myIntentFilter.addAction(context.getString(R.string.broadcast_id));
context.registerReceiver(myBroadcastReceiver, myIntentFilter);

// place your BroadcastReceiver in MainActivity, your UploadData class
public class MyBroadcastReceiver extends BroadcastReceiver {

    public MyBroadcastReceiver(){
        super();
    }
    @Override public void onReceive(Context context, Intent intent) {

        Log.d(TAG, "Broadcast received");
        if(intent.getAction() != null && intent.getAction().equals(context.getString(R.string.broadcast_id)) ){
            // do something
        }
    }
}

// send Broadcasts from where you want to act, your UploadAct class.
Intent intent = new Intent();
intent.setAction(context.getString(R.string.broadcast_id));
context.sendBroadcast(intent);
Log.d(TAG, "Broadcast sent.");

// you can unregister this receiver in onDestroy() method
context.unregisterReceiver(myBroadcastReceiver);

Answer 4

你也可以使用一个界面来更新你的用户界面作为一个监听器

首先，创建一个接口

public interface UpdateTextListener {
    void updateText(String data);
}

然后，在UploadData类中调用它的方法

 public class UploadData extends UploadAct {

     UpdateTextListener listener;

     public void doSomethig(){
         listener.updateText("data to be loaded");
     }
 }

然后，通过听这个方法更新你的UploadAct

public class UploadAct extends MainActivity  implements UpdateTextListener {

     @Override
     public void updateText(String  data) {
         textview.setText(data);
     }
}