putExtra() and getBooleanExtra() in android

问题:

I'm developing an app that implements mapsView. I have two activities that lead to the mapsView activity. activity_A will lead to mapsView activity, and the mapsView activity will lead to the activity_B. I'm implementing putExtra() and getBooleanExtra() in my code.

Here's my code in activity_A

case R.id.buttonMaps:
    Intent i = new Intent(MainActivity.this, MapsActivity.class);
    i.putExtra("maps", false);
    startActivity(i);
break;

Here's my code in activity_B

buttonNavigasi.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        Intent i = new Intent(DetailActivity.this,MapsActivity.class);
        i.putExtra("nama", daftarNama);
        i.putExtra("deskripsi", daftarDeskripsi);
        i.putExtra("foto", daftarFoto);
        i.putExtra("marker", daftarMarker);
        i.putExtra("lat", daftarLat);
        i.putExtra("lng", daftarLng);
        i.putExtra("maps", true);
        startActivity(i);
     }
});

Here's my code in mapsView activity

case R.id.action_refresh:
     removeAllMarkers();
     if(i.getBooleanExtra("maps", true)) {
         mMyMarkersArray.add(new MyMarker(i.getStringExtra("nama"), i.getStringExtra("deskripsi"), i.getStringExtra("foto"), i.getStringExtra("marker"), Double.parseDouble(i.getStringExtra("lat")), Double.parseDouble(i.getStringExtra("lng"))));
         UI_HANDLER.postDelayed(UI_UPDATE_RUNNABLE, 500);
     }
     else {
         registerReceiver(mNetworkReceiver, new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION));
     }
     getCurrentLocation();
     return true;

The problem is when the mapsView go to activity_B and in activity_B I pressed the back button (back to mapsView activity) then I pressed the refresh icon in mapsView, the mapsView will go to this code

if(i.getBooleanExtra("maps", true)) {
     mMyMarkersArray.add(new MyMarker(i.getStringExtra("nama"), i.getStringExtra("deskripsi"), i.getStringExtra("foto"), i.getStringExtra("marker"), Double.parseDouble(i.getStringExtra("lat")), Double.parseDouble(i.getStringExtra("lng"))));
     UI_HANDLER.postDelayed(UI_UPDATE_RUNNABLE, 500);
}

Why it doesn't go to the else statement in mapsView activity? I do not press the buttonNavigasi in activity_B, but I just press the back button. What's wrong with my code?

Any answer will be greatly appreciated.

Thanks in advance.

回答1:

When you press back button your previous activity is just resumed

private boolean registerRecr=false;

@Override
protected void onRestart() {
    // TODO Auto-generated method stub
    super.onRestart();

    registerRecr=true;


}
@Override
protected void onStart() {
    // TODO Auto-generated method stub
    super.onStart();

}

@Override
protected void onResume() {
    // TODO Auto-generated method stub
    super.onResume();

}

 case R.id.action_refresh:
 removeAllMarkers();
 if(i.getBooleanExtra("maps", true)&& registerRecr==false) {
     mMyMarkersArray.add(new MyMarker(i.getStringExtra("nama"), i.getStringExtra("deskripsi"), i.getStringExtra("foto"), i.getStringExtra("marker"), Double.parseDouble(i.getStringExtra("lat")), Double.parseDouble(i.getStringExtra("lng"))));
     UI_HANDLER.postDelayed(UI_UPDATE_RUNNABLE, 500);
 }
 else {
     registerReceiver(mNetworkReceiver, new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION));
 }
 getCurrentLocation();
 return true;

回答2:

if(i.getBooleanExtra("maps", true)) {

Here you are telling it to get maps, if it doesn't exist it will simply be true.

If you set it to false, you will get the correct answer.

回答3:

Because when you do not assign any value he get by default true i.getBooleanExtra("maps", true) try with i.getBooleanExtra("maps", false):

case R.id.action_refresh:
     removeAllMarkers();
     if(i.getBooleanExtra("maps", false)) {
         mMyMarkersArray.add(new MyMarker(i.getStringExtra("nama"), i.getStringExtra("deskripsi"), i.getStringExtra("foto"), i.getStringExtra("marker"), Double.parseDouble(i.getStringExtra("lat")), Double.parseDouble(i.getStringExtra("lng"))));
         UI_HANDLER.postDelayed(UI_UPDATE_RUNNABLE, 500);
     }
     else {
         registerReceiver(mNetworkReceiver, new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION));
     }
     getCurrentLocation();
     return true;

EDIT

Following the life cycle of an activity when you press back button maybe this solution in MapsActivity could be more useful for you:

Intent i;
boolean refresh=false;
//YOUR CODE
 @Override
    protected void onCreate(Bundle savedInstanceState) {
    //YOUR CODE
    i = getIntent();
    //YOUR CODE
    }

    @Override
    protected void onResume() {
    //YOUR CODE
        if(i!=null){
                refresh = i.getBooleanExtra("maps", false);
        }
    //YOUR CODE 
    }

    @Override
    protected void onPause() {
        //YOUR CODE
        i=null;
       //YOUR CODE 
    }
    //YOUR CODE
    case R.id.action_refresh:
     removeAllMarkers();
     if(refresh) {
         mMyMarkersArray.add(new MyMarker(i.getStringExtra("nama"), i.getStringExtra("deskripsi"), i.getStringExtra("foto"), i.getStringExtra("marker"), Double.parseDouble(i.getStringExtra("lat")), Double.parseDouble(i.getStringExtra("lng"))));
         UI_HANDLER.postDelayed(UI_UPDATE_RUNNABLE, 500);
     }
     else {
         registerReceiver(mNetworkReceiver, new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION));
     }
     getCurrentLocation();
     return true;
     //YOUR CODE

Hope help

回答4:

you could override your own onBackPressed

@Override
public void onBackPressed() {

}

to force the user to navigate through your buttons or to pass through the onBackPressed the value of the boolean that you want

or you could simply finish() each activity after using the startActivity() so you won't use too much memory in the same time avoid those loops that way you can only start the map through the intent