[英]Getting NULL in context while auto restart with BROADCAST RECEIVER in Android app
I am developing android application which need auto restart when restart device for that I am using broadcast receiver with action BOOT_COMPLETED.我正在开发 android 应用程序,该应用程序需要在重启设备时自动重启,因为我正在使用具有操作 BOOT_COMPLETED 的广播接收器。
Broadcast receiver is receiving message when I am restarting device but in restart method I want to start main activity for that I used Intent but in onReceive method of receiver I am getting null context so I am unable to restart main Activity.当我重新启动设备时,广播接收器正在接收消息,但在重新启动方法中我想启动主要活动,因为我使用了 Intent,但在接收器的 onReceive 方法中,我得到 null 上下文,所以我无法重新启动主要活动。
Below is code for that.下面是代码。
MainActivity.java MainActivity.java
private Object activity;
private TextView tvImeiNum;
private BroadcastReceiver rebootreceiver;
private IntentFilter filter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tvImeiNum = (TextView)findViewById(R.id.tv_imeinum);
filter = new IntentFilter();
filter.addAction(Intent.ACTION_BOOT_COMPLETED);
filter.addAction(Intent.ACTION_REBOOT);
rebootreceiver = new BootUpReceiver(MainActivity.this);
LocalBroadcastManager.getInstance(this).registerReceiver(rebootreceiver,
filter);//registering receiver
generateUniqueCode();
}
BootupReceiver.java BootupReceiver.java
public class BootUpReceiver extends BroadcastReceiver {
MainActivity ma;
public BootUpReceiver(MainActivity maContext){
ma=maContext;
}
public BootUpReceiver(){
}
@RequiresApi(api = Build.VERSION_CODES.M)
@Override
public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals("android.intent.action.BOOT_COMPLETED")) {
Log.d("TAG REBOOT", "onReceive: " + intent);
Log.d("Reboot complete", "connection");
GlobalTool.restartApplication(context);
}
}
}
GlobalTool.java GlobalTool.java
public class GlobalTool {
@RequiresApi(api = Build.VERSION_CODES.M)
public static void restartApplication(Context context) {
Log.d("IN App restart:", "");
Log.d("TAG", "restartApplication: ");
if(context != null)
{
Log.d("TAG NULL", "restartApplication: ");
Intent mainIntent = new Intent(context, MainActivity.class);
AlarmManager alarmMgr = (AlarmManager)
context.getSystemService(ALARM_SERVICE);
TaskStackBuilder stackBuilder = TaskStackBuilder.create(context);
stackBuilder.addNextIntent(mainIntent);
PendingIntent pendingIntent = stackBuilder.getPendingIntent(0,
PendingIntent.FLAG_UPDATE_CURRENT);
long alarmTime = System.currentTimeMillis() + (1 * 1000);
alarmMgr.setExact(AlarmManager.RTC_WAKEUP, alarmTime, pendingIntent);
Log.d("TAG", "restartApplication: 111");
Log.d("TAG", "restartApplication: 111");
}
else {
Intent mainIntent = new Intent(context, MainActivity.class);
AlarmManager alarmMgr = (AlarmManager)
context.getSystemService(ALARM_SERVICE);
TaskStackBuilder stackBuilder = TaskStackBuilder.create(context);
stackBuilder.addNextIntent(mainIntent);
PendingIntent pendingIntent = stackBuilder.getPendingIntent(0,
PendingIntent.FLAG_UPDATE_CURRENT);
long alarmTime = System.currentTimeMillis() + (1 * 1000);
alarmMgr.setExact(AlarmManager.RTC_WAKEUP, alarmTime, pendingIntent);
Log.d("TAG", "restartApplication: 111");
Log.d("TAG", "restartApplication: 111");
}
}
}
AndroidManifest.xml AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
package="com.example.kioskappdemo">
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission
android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
<application
android:name="KioskApplication"
android:allowBackup="true"
android:dataExtractionRules="@xml/data_extraction_rules"
android:fullBackupContent="@xml/backup_rules"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/Theme.KioskAppDemo"
tools:targetApi="31"
tools:ignore="Instantiatable">
<service
android:name=".RebootService"
android:enabled="true"
android:exported="true"></service>
<activity
android:name=".MainActivity"
android:exported="true"
android:screenOrientation="landscape"
android:theme="@style/Theme.AppCompat.NoActionBar">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category
android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<receiver
android:name=".Activity.BootUpReceiver"
android:enabled="true"
android:exported="true">
<intent-filter >
<action
android:name="android.intent.action.BOOT_COMPLETED" />
<action android:name="android.intent.action.REBOOT" />
<action
android:name="android.intent.action.QUICKBOOT_POWERON" />
<action android:name="com.reboot.test" />
<action
android:name="android.intent.action.TIMEZONE_CHANGED" />
<action
android:name="android.intent.action.DATE_CHANGED" />
</intent-filter>
</receiver>
</application>
</manifest>
Some you code improvements:一些代码改进:
public class BootUpReceiver extends BroadcastReceiver {
public BootUpReceiver(){
//TODO log
}
...
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
<receiver
android:name=".activity.BootUpReceiver"
android:enabled="true"
android:exported="true"
android:permission="android.permission.RECEIVE_BOOT_COMPLETED">
<intent-filter >
<action android:name="android.intent.action.BOOT_COMPLETED" />
</intent-filter>
</receiver>
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