试试这个

Intent aint = new Intent(getApplicationContext(), AlarmReceiver.class);
aint.putExtra("msg", msg);
aint.putExtra("phone", phone);


PendingIntent pendingIntent = PendingIntent.getBroadcast(
    getApplicationContext(),
    id, 
    aint,
    // as stated in the comments, this flag is important!
    PendingIntent.FLAG_UPDATE_CURRENT);

记住在PendingIntent构造函数中放置一个唯一的id，否则当您尝试获取putExtra值时，可能会得到一些奇怪的结果。

PendingIntent pendingIntent = PendingIntent.getBroadcast(
           getApplicationContext(), 
           UUID.randomUUID().hashCode(), 
           aint, 
           PendingIntent.FLAG_UPDATE_CURRENT
    );

您必须使用getStringExtra()并确保String不为空：

Intent intent = getIntent();    
     msg = intent.getStringExtra("msg");
     phonen = intent.getStringExtra("phone");

     if(msg!=null){
      Toast.makeText(context,msg,
        Toast.LENGTH_LONG).show();
     }

并将您的putExtras反转到PendingIntent之前：

Intent aint = new Intent(getApplicationContext(), AlarmReceiver.class);
   aint.putExtra("msg", msg);
   aint.putExtra("phone", phone);
   PendingIntent pendingIntent = PendingIntent.getBroadcast(getApplicationContext(), id, aint, PendingIntent.FLAG_UPDATE_CURRENT);

这是因为您首先要初始化Intent并添加到PendingIntent。之后您要在Intent中添加信息。您应该先向Intent添加信息，然后再将此Intent添加到PendingIntent。

在我的例子中，我缺少PendingIntent.FLAG_UPDATE_CURRENT作为标志。

final Intent my_intent = new Intent(this.context , Alarm_Receiver.class);

    //put in extra string into my intent
    //tell the clock that the user pressed the "alarm on button"
    my_intent.putExtra("extra" , 1);
    int state = my_intent.getExtras().getInt("extra");
    Log.i("extraa" , "the state in the main activity in alarm on Button is: " + state);

我遇到了同样的问题，我发现应该在涉及Intent之前先考虑putExtra

请使用FLAG_IMMUTABLE | PendingIntent.FLAG_UPDATE_CURRENT

在Kotlin，我已经这样解决了我的问题。我试图从另一个服务类启动服务。谢谢你的其他回答。

var float_intent = Intent(this,FloatingViewService::class.java)
    float_intent.putExtra("sended_name",customer_name)

    val pending_float_intent = PendingIntent.getService(
        this,UUID.randomUUID().hashCode(),float_intent,FLAG_IMMUTABLE or PendingIntent.FLAG_UPDATE_CURRENT
    )