App crash when trying to access mapfragment

Question

i am creating a project for school with a mapfragment and a button, but when i try to access my map, it crashes completely this is my code:

package com.helloandroid.mapview;

import android.app.FragmentManager;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;

import com.google.android.gms.maps.*;
import com.google.android.gms.maps.model.*;


public class MainActivity extends ActionBarActivity {
    GoogleMap myMap;
    Button btnShow;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
                .add(R.id.container, new PlaceholderFragment())
                .commit();
    }
    btnShow = (Button) findViewById(R.id.btnShow);

this is the line where it crashes:

SupportMapFragment mapFrag = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);

    myMap = mapFrag.getMap();



}




/**
 * A placeholder fragment containing a simple view.
 */
public static class PlaceholderFragment extends Fragment {

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main, container, false);
        return rootView;
    }
}

}

this is my logcat result:

01-09 20:19:57.475  28744-28744/? E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.helloandroid.mapview/com.helloandroid.mapview.MainActivity}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2306)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2358)
            at android.app.ActivityThread.access$600(ActivityThread.java:156)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1340)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:153)
            at android.app.ActivityThread.main(ActivityThread.java:5297)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at com.helloandroid.mapview.MainActivity.onCreate(MainActivity.java:34)
            at android.app.Activity.performCreate(Activity.java:5122)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1081)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2270)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2358)
            at android.app.ActivityThread.access$600(ActivityThread.java:156)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1340)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:153)
            at android.app.ActivityThread.main(ActivityThread.java:5297)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
            at dalvik.system.NativeStart.main(Native Method)

this is the mapfragment

    <fragment
        android:id="@+id/map"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:name="com.google.android.gms.maps.MapFragment"
        android:layout_below="@+id/btnShow" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Show"
        android:id="@+id/btnShow"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" />

</RelativeLayout>

does anybody know how i can fix this?

thanks in advance

Please include the full details from LogCat about the crash. — Carl Anderson, Jan 09 '14 at 19:15

Ernir Erlingsson · Accepted Answer · 2014-01-10T15:38:11.607

Correct setup

First off you need to check if the device has the correct Google Play services, if it hasn't got it properly set up, you will not be able to use the map at all.

    if (GooglePlayServicesUtil.isGooglePlayServicesAvailable(this) != ConnectionResult.SUCCESS) {
        // Handle the case here
    }

Second, you don't get any guarantee that the map will be ready, therefore you will need to try to set up the map multiple times, e.g. call this method both from OnCreate(..) and onResume(..).

private void setUpMapIfNeeded() {
    // Do a null check to confirm that we have not already instantiated the map.
    if (mMap == null) {
        // Try to obtain the map from the SupportMapFragment.
        mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map)).getMap();
        // Check if we were successful in obtaining the map.
        if (mMap != null) {
            // here you can setup the map the way you want
        }
    }
}

Your error

You are getting a NullPointerException when you access the SupportMapFragment? Check the following:

Are you sure that you have included the android-support-v4.jar support library?
Are you sure that R.id.map exists?
Do you have the google play services lib correctly included in your project?

If you still run into problems you should include the xml for the map fragment.

EDIT

Your XML setup should have this

class="com.google.android.gms.maps.SupportMapFragment", i.e. remove the android:name attribute from fragment and add the class.

i still get the same error when i use this, but i've attached the xml — Kaspaar, Jan 10 '14 at 14:02

score 1 · Answer 2 · answered Jan 10 '14 at 14:08

In your xml file you wrote:

android:name="com.google.android.gms.maps.MapFragment"

and in your java code you can access it by

SupportMapFragment mapFrag = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);

So just you have to need to change from

android:name="com.google.android.gms.maps.MapFragment"

to

android:name="com.google.android.gms.maps.SupportMapFragment"

in your xml file.

score 0 · Answer 3 · answered Dec 08 '15 at 03:57

Simply Replace

 <?xml version="1.0" encoding="utf-8"?>
    <fragment xmlns:android="http://schemas.android.com/apk/res/android
    android:id="@+id/map"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    class="com.google.android.gms.maps.SupportMapFragment" />

with this

<?xml version="1.0" encoding="utf-8"?>
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/map"
    android:name="com.google.android.gms.maps.MapFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

and access Mapview like this

GoogleMap googleMap;

..
..

        googleMap = ((MapFragment) getActivity().getFragmentManager()
                .findFragmentById(R.id.map)).getMap();
        googleMap.getUiSettings().setZoomControlsEnabled(true);

Hope it will help somebody.

App crash when trying to access mapfragment

3 Answers3

Correct setup

Your error

EDIT

Linked