Bundle is null after setting it in Intent

问题:

I know there are questions like: android-intent-bundle-always-null and intent-bundle-returns-null-every-time but there is no correct answer.

In my Activity 1:

public void goToMapView(Info info) {
    Intent intent = new Intent(getApplicationContext(), MapViewActivity.class);
    //intent.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
    intent.putExtra("asdf", true);
    info.write(intent);
    startActivity(intent);
}

In Info:

public void write(Intent intent) {
    Bundle b = new Bundle();
    b.putInt(AppConstants.ID_KEY, id);
    ... //many other attributes
    intent.putExtra(AppConstants.BUNDLE_NAME, b);
}
public static Info read(Bundle bundle) {
    Info info = new Info();
    info.setId(bundle.getInt(AppConstants.ID_KEY));
    ... //many other attributes
    return info;
}

In MapViewActivity (Activity 2):

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

    Bundle extras = getIntent().getBundleExtra(AppConstants.BUNDLE_NAME);
    info = Info.read(extras);
    ...
}

Problem is that extras bundle is always null. I have debugged it and Intent (intent = getIntent()) has all fields set to null except one indicating what class this is (MapViewActivity).

I've also tried putting the bundle via intent.putExtras(b) with the same effect. The intent.putExtra("asdf", true) is for debugging reasons only - I cannot get this data too (because getIntent() has almost all fields set to null).

EDIT

The answers below are correct and working. This was my fault. I didn't correctly passed my bundle to new intent.

回答1:

I am not sure what "Info" is for, but I suggest making the most basic passing of data from one activity to another first before involving other data objects.

Activity1

    Intent intent = new Intent(Activity1.this, Activity2.class);
    intent.putExtra("asdf", true);
    info.write(intent);
    startActivity(intent);

Activity2

    Bundle bundle = getIntent.getExtras();
    if (bundle!=null) {
        if(bundle.containsKey("asdf") {
            boolean asdf = bundle.getBooleanExtra("asdf");
            Log.i("Activity2 Log", "asdf:"+String.valueOf(asdf));
        }
    } else {
        Log.i("Activity2 Log", "asdf is null");

    }

回答2:

Activity 1

Intent intent = new Intent(getApplicationContext(), MapViewActivity.class);

        Bundle b = new Bundle();
         b.putBoolean("asdf", true);
         b.putInt(AppConstants.ID_KEY, id);
         intent.putExtras(b);

         startActivity(intent);

Activity 2

Bundle extras = getIntent().getExtras();

 boolean bool = extras.getBoolean("asdf");
 int m_int = extras.getInt(AppConstants.ID_KEY,-1);