Custom Layout return null

Question

I followed this guide on how to have buttons inside a snippet Link

The problem is that at final MapWrapperLayout mapWrapperLayout = (MapWrapperLayout) findViewById(R.id.map_relative_layout); return null value and a null pointer exception at this line of code:

        mapWrapperLayout.init(map, getPixelsFromDp(getApplicationContext(), 39 + 20));

This my code of the method oncreate of my main activity that extend Activity:

super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    final MapFragment mapFragment = (MapFragment)getFragmentManager().findFragmentById(R.id.map);
    final MapWrapperLayout mapWrapperLayout = (MapWrapperLayout) findViewById(R.id.map_relative_layout);
    final GoogleMap map = mapFragment.getMap();

    // MapWrapperLayout initialization
    // 39 - default marker height
    // 20 - offset between the default InfoWindow bottom edge and it's content bottom edge 
    mapWrapperLayout.init(map, getPixelsFromDp(getApplicationContext(), 39 + 20)); 

    // We want to reuse the info window for all the markers, 
    // so let's create only one class member instance
    this.infoWindow = (ViewGroup)getLayoutInflater().inflate(R.layout.infowindow, null);
    this.infoTitle = (TextView)infoWindow.findViewById(R.id.title);
    this.infoSnippet = (TextView)infoWindow.findViewById(R.id.snippet);
    this.infoButton = (Button)infoWindow.findViewById(R.id.button);

    // Setting custom OnTouchListener which deals with the pressed state
    // so it shows up 
    this.infoButtonListener = new OnInfoWindowElemTouchListener(infoButton,
            getResources().getDrawable(R.drawable.common_signin_btn_icon_dark),
            getResources().getDrawable(R.drawable.common_signin_btn_icon_disabled_dark)) 
    {
        @Override
        protected void onClickConfirmed(View v, Marker marker) {
            // Here we can perform some action triggered after clicking the button
            Toast.makeText(MainActivity.this, marker.getTitle() + "'s button clicked!", Toast.LENGTH_SHORT).show();
        }
    }; 
    this.infoButton.setOnTouchListener(infoButtonListener);


    map.setInfoWindowAdapter(new InfoWindowAdapter() {
        @Override
        public View getInfoWindow(Marker marker) {
            return null;
        }

        @Override
        public View getInfoContents(Marker marker) {
            // Setting up the infoWindow with current's marker info
            infoTitle.setText(marker.getTitle());
            infoSnippet.setText(marker.getSnippet());
            infoButtonListener.setMarker(marker);

            // We must call this to set the current marker and infoWindow references
            // to the MapWrapperLayout
            mapWrapperLayout.setMarkerWithInfoWindow(marker, infoWindow);
            return infoWindow;
        }
    });

    // Let's add a couple of markers
    map.addMarker(new MarkerOptions()
        .title("Prague")
        .snippet("Czech Republic")
        .position(new LatLng(50.08, 14.43)));

    map.addMarker(new MarkerOptions()
        .title("Paris")
        .snippet("France")
        .position(new LatLng(48.86,2.33)));

    map.addMarker(new MarkerOptions()
        .title("London")
        .snippet("United Kingdom")
        .position(new LatLng(51.51,-0.1)));
}

MapWrapperLayout is the same of the guide:

public class MapWrapperLayout extends RelativeLayout {
/**
 * Reference to a GoogleMap object 
 */
private GoogleMap map;

/**
 * Vertical offset in pixels between the bottom edge of our InfoWindow 
 * and the marker position (by default it's bottom edge too).
 * It's a good idea to use custom markers and also the InfoWindow frame, 
 * because we probably can't rely on the sizes of the default marker and frame. 
 */
private int bottomOffsetPixels;

/**
 * A currently selected marker 
 */
private Marker marker;

/**
 * Our custom view which is returned from either the InfoWindowAdapter.getInfoContents 
 * or InfoWindowAdapter.getInfoWindow
 */
private View infoWindow;    

public MapWrapperLayout(Context context) {
    super(context);
}

public MapWrapperLayout(Context context, AttributeSet attrs) {
    super(context, attrs);
}

public MapWrapperLayout(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
}

/**
 * Must be called before we can route the touch events
 */
public void init(GoogleMap map, int bottomOffsetPixels) {
    this.map = map;
    this.bottomOffsetPixels = bottomOffsetPixels;
}

/**
 * Best to be called from either the InfoWindowAdapter.getInfoContents 
 * or InfoWindowAdapter.getInfoWindow. 
 */
public void setMarkerWithInfoWindow(Marker marker, View infoWindow) {
    this.marker = marker;
    this.infoWindow = infoWindow;
}

@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
    boolean ret = false;
    // Make sure that the infoWindow is shown and we have all the needed references
    if (marker != null && marker.isInfoWindowShown() && map != null && infoWindow != null) {
        // Get a marker position on the screen
        Point point = map.getProjection().toScreenLocation(marker.getPosition());

        // Make a copy of the MotionEvent and adjust it's location
        // so it is relative to the infoWindow left top corner
        MotionEvent copyEv = MotionEvent.obtain(ev);
        copyEv.offsetLocation(
            -point.x + (infoWindow.getWidth() / 2), 
            -point.y + infoWindow.getHeight() + bottomOffsetPixels);

        // Dispatch the adjusted MotionEvent to the infoWindow
        ret = infoWindow.dispatchTouchEvent(copyEv);
    }
    // If the infoWindow consumed the touch event, then just return true.
    // Otherwise pass this event to the super class and return it's result
    return ret || super.dispatchTouchEvent(ev);
}

}

This is my xml file with the tag of my project

    <?xml version="1.0" encoding="utf-8"?>
<com.example.testmappa.MapWrapperLayout xmlns:android="http://schemas.android.com/apk/res/android"
          xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/map_relative_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >



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

</com.example.testmappa.MapWrapperLayout>

and this my home activity layout:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >

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

finally my logcat

    03-13 17:50:56.386: E/AndroidRuntime(21055): FATAL EXCEPTION: main
03-13 17:50:56.386: E/AndroidRuntime(21055): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.testmappa/com.example.testmappa.MainActivity}: java.lang.NullPointerException
03-13 17:50:56.386: E/AndroidRuntime(21055):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2249)
03-13 17:50:56.386: E/AndroidRuntime(21055):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2299)
03-13 17:50:56.386: E/AndroidRuntime(21055):    at android.app.ActivityThread.access$700(ActivityThread.java:154)
03-13 17:50:56.386: E/AndroidRuntime(21055):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1284)
03-13 17:50:56.386: E/AndroidRuntime(21055):    at android.os.Handler.dispatchMessage(Handler.java:99)
03-13 17:50:56.386: E/AndroidRuntime(21055):    at android.os.Looper.loop(Looper.java:137)
03-13 17:50:56.386: E/AndroidRuntime(21055):    at android.app.ActivityThread.main(ActivityThread.java:5306)
03-13 17:50:56.386: E/AndroidRuntime(21055):    at java.lang.reflect.Method.invokeNative(Native Method)
03-13 17:50:56.386: E/AndroidRuntime(21055):    at java.lang.reflect.Method.invoke(Method.java:511)
03-13 17:50:56.386: E/AndroidRuntime(21055):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
03-13 17:50:56.386: E/AndroidRuntime(21055):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
03-13 17:50:56.386: E/AndroidRuntime(21055):    at dalvik.system.NativeStart.main(Native Method)
03-13 17:50:56.386: E/AndroidRuntime(21055): Caused by: java.lang.NullPointerException
03-13 17:50:56.386: E/AndroidRuntime(21055):    at com.example.testmappa.MainActivity.onCreate(MainActivity.java:44)
03-13 17:50:56.386: E/AndroidRuntime(21055):    at android.app.Activity.performCreate(Activity.java:5255)
03-13 17:50:56.386: E/AndroidRuntime(21055):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1097)
03-13 17:50:56.386: E/AndroidRuntime(21055):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2213)

Can anyone explain me why i have this error? Thanks!

Raghunandan · Accepted Answer · 2014-03-13T17:00:41.933

1

Change this

final MapWrapperLayout mapWrapperLayout = (MapWrapperLayout) findViewById(R.layout.map_relative_layout);

to

final MapWrapperLayout mapWrapperLayout = (MapWrapperLayout) findViewById(R.id.map_relative_layout);

findViewById looks for a view with the id in the current inflated layout.

Edit:

You have

setContentView(R.layout.activity_main);
final MapWrapperLayout mapWrapperLayout = (MapWrapperLayout) findViewById(R.id.map_relative_layout);

While activity_main.xml does not have the custom layout.

edited Mar 13 '14 at 17:00

answered Mar 13 '14 at 16:43

Raghunandan

132,755
26
225
256

@Frank what problem? post the activity code and stacktrace – Raghunandan Mar 13 '14 at 16:52
@Frank post the code where you initialize the custom layout and also the stacktrace – Raghunandan Mar 13 '14 at 16:53
@Frank its obvious you get NPE coz activity_main.xml does not have the custom layout. If you read my post again there is a line that explains the same even before the edit. Pls understand – Raghunandan Mar 13 '14 at 17:01

score 0 · Answer 2 · answered Mar 13 '14 at 16:59

Check if it is 'null' right after you assign it. If that's the case then you probably don't set the current content view appropriately.

setContentView(R.layout./*nameOfTheXmlFileContainingThisLayout.xml*/);

before calling your

final MapWrapperLayout mapWrapperLayout = (MapWrapperLayout) findViewById(R.id.map_relative_layout);

Without the current xml content view loaded when you try and access the MapWrapperLayout, it will always return null cause it is looking in the wrong place.

Custom Layout return null

2 Answers2