我如何访问我的UI从MainActivity从Broadcast Receiver类

Question

我是Android Studio的新用户，我正在创建一个自定义通知应用程序，我想在Broadcast Receiver类中使用我的MainActivity类中的EditText。我该怎么做呢?

广播接收码:

`package com.example.notificationscreator;
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.widget.EditText;
import androidx.core.app.NotificationCompat;
import androidx.core.app.NotificationManagerCompat;
public class MyReceiver extends BroadcastReceiver {

@Override
public void onReceive(Context context, Intent intent) {
NotificationCompat.Builder Build = new NotificationCompat.Builder(context, "Notified");
Build.setSmallIcon(R.drawable.ic_stat_name);
Build.setContentTitle("");
Build.setStyle(new NotificationCompat.BigTextStyle().bigText(""));
NotificationManagerCompat Managercompats = NotificationManagerCompat.from(context);
Managercompats.notify(1, Build.build());
}


}`

主活动代码:

`package com.example.notificationscreator;
import static com.example.notificationscreator.R.*;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.NotificationCompat;
import androidx.core.app.NotificationManagerCompat;
import android.app.AlarmManager;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.os.SystemClock;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import java.util.Calendar;
import java.util.Random;
public class MainActivity2 extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(layout.activity_main2);
Button btnmain = findViewById(R.id.button4);
Button Displaynotif = findViewById(R.id.button3);
EditText Timedisplay = findViewById(R.id.editTextTime);
Integer Time = Integer.parseInt(Timedisplay.getText().toString());
btnmain.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Backmainpage();
}
});
if(Build.VERSION.SDK_INT >=Build.VERSION_CODES.O){
NotificationChannel channel = new NotificationChannel("Notified","Notification", NotificationManager.IMPORTANCE_HIGH);
NotificationManager manager = getSystemService(NotificationManager.class);
manager.createNotificationChannel(channel);
}
Displaynotif.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
int Randnum = new Random().nextInt(80);
Intent intent= new Intent(MainActivity2.this,MyReceiver.class);
PendingIntent pendingintention = PendingIntent.getBroadcast(MainActivity2.this,0, intent,0);
AlarmManager am = (AlarmManager)getSystemService(ALARM_SERVICE);
long timeonclick = System.currentTimeMillis();
long timeafterclick = 10000;
am.set(AlarmManager.RTC_WAKEUP,timeonclick+timeafterclick,pendingintention);
}
});
}
public void Backmainpage(){
Intent intention2 = new Intent(this,MainActivity.class);
startActivity(intention2);
}

}`

我已经试着用MainActivity2 Mainactivity = new MainActivity2();但是我仍然不能从主活动

访问UI

Answer 1

您可以使用另一个BroadcastReceiver与您的activity通信，如下面的示例。

在您的broadcast receiver中添加以下代码。

@Override
public void onReceive(Context context, Intent intent) {
//... your other code
Intent intent = new Intent();
intent.setAction("CustomAction"); // use your action name
intent.putExtra("key", "Value");  // you can pass data like this
context.sendBroadcast(intent); // fire broadcast receiver
}

现在，从Activity

注册您的自定义broadcast receiver

@Override
protected void onResume() {
super.onResume();
IntentFilter filter = new IntentFilter();
filter.addAction("CustomAction"); // use your custom action name
BroadcastReceiver updateUIReciver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
//You will get your data here
//Update UI based on your data.
if (intent != null) {
String data = intent.getStringExtra("key");
}
}
};
registerReceiver(updateUIReciver, filter); // register broad cast receiver.
}

Answer 2

public class MainActivity2 extends AppCompatActivity {
EditText Timedisplay;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(layout.activity_main2);
Timedisplay = findViewById(R.id.editTextTime);

//register your broadcast here   
LocalBroadcastManager.getInstance(this).registerReceiver(mMessageReceiver, new IntentFilter("messageevent"));
}
}      
private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, final Intent intent) {
// Get extra data included in the Intent
String message = intent.getStringExtra("key");
Log.e(TAG, "Got message: " + message);
if(message != null && !message.isEmpty()) {
//Toast.makeText(context, message, Toast.LENGTH_SHORT).show();
String timedisplay = Timedisplay.getText();
}
}
};
//call this from anywhere you want to trigger the broadcoast
Intent i = new Intent("messageevent");
// You can also include some extra data.
i.putExtra("key", "value");
LocalBroadcastManager.getInstance(CheckUpdate.this).sendBroadcast(i);