在将值从Activity传递给服务时获取空指针异常

Question

In Activity i have passed a value paramVal like this

 Intent srv = new Intent(this, TestService.class);
    startService(srv);

     //Intent intent =new Intent("com.example.firstapplication.STARTACTIVITY"); 
     //intent.putExtra("myFirstKey", paramVal); 

    //intent.putExtra("myFirstKey", paramVal); 

    Bundle bundle = new Bundle();
    bundle.putCharSequence("myFirstKey", paramVal);
    intent.putExtras(bundle);

and in service I am retrieving a value like this

 @Override
  public void onStart(Intent intent, int startId) {
      // TODO Auto-generated method stub
      super.onStart(intent, startId);

      Bundle bundle = intent.getExtras();
      data = (String) bundle.getCharSequence("myFirstKey");

      System.out.println("data checking"+data);
     }

but i am getting null pointer exception for the line

data = (String) bundle.getCharSequence("myFirstKey");

in service

should i have to call onstart method in service somewhere. Please let me know where is the problem??

Answer 1

In your Activity:

Intent lIntent = new Intent(this, TestService.class);
lIntent.putExtra("myFirstKey", <your String param here>);
startService(lIntent);

In your Service:

String lDataString = intent.getStringExtra("myFirstKey");

As a sidenote:

• please override onStartCommand() in your service, since onStart() is deprecated
• it is not required to call super.onStartCommand() (or super.onStart() for that matter) when extending the Service class

Answer 2

你在传递额外内容之前就开始了这项服务......

Answer 3

It might work, you are changing the order of instruction. the service is starting before inserting values in the intent.

Intent srv = new Intent(this, TestService.class);
Bundle bundle = new Bundle();
    bundle.putCharSequence("myFirstKey", paramVal);
    intent.putExtras(bundle);
startService(srv);