Question

我在地图上编写了显示balloonView的程序，当我运行程序时，程序已停止。我读了LogCat并获得了NullPointerException，但我不知道问题出在哪里以及哪一行。

location.java

 public class Location extends MapActivity {
private FrameLayout linear;
private MapView map;
private MapController controller;
private EditText text_location;
GeoPoint searchLocation;
GeoPoint mylocation;
double myLatitude=0;
double myLongitude=0;
List<Overlay> mapOverlays;
Drawable drawable;
SimpleItemizedOverlay itemizedOverlay;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.location);
    initMapView();
    //initZoomControls();
    initMyLocation();
    //Not complete this method
    text_location.setOnKeyListener(new OnKeyListener(){
        public boolean onKey(View view, int keyCode,KeyEvent event){
            if(keyCode==KeyEvent.KEYCODE_ENTER){
                // The map should shows a location that user writes in edittex.
                Geocoder geo=new Geocoder(getApplicationContext(),Locale.getDefault());

                List<Address> address;
                try {
                    address = geo.getFromLocationName(text_location.getText().toString(),3);
                    if(address.size()>0){
                        searchLocation=new GeoPoint((int)(address.get(0).getLatitude()*1e6),(int)(address.get(0).getLongitude()*1e6));
                        controller.animateTo(searchLocation);
                        controller.setZoom(12);
                        //

                    }
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

                return true;
            }
            return false;
        }
    });
    mapOverlays=map.getOverlays();
    drawable=getResources().getDrawable(R.drawable.marker);
    itemizedOverlay=new SimpleItemizedOverlay(drawable,map);
    OverlayItem overlayItem=new OverlayItem(searchLocation,text_location.getText().toString(),"for test");
    itemizedOverlay.addOverlay(overlayItem);
    mapOverlays.add(itemizedOverlay);

}
@Override
protected boolean isRouteDisplayed() {
    return false;
}
private void initMapView() {
    linear = (FrameLayout) findViewById(R.id.frame);
    text_location=(EditText)findViewById(R.id.edit_text);
    map = (MapView) findViewById(R.id.map);
    controller = map.getController();
    map.setSatellite(true);
}
/*private void initZoomControls() {
    //WHY???
    View zoomControls = map.getZoomControls();
    FrameLayout.LayoutParams p = new FrameLayout.LayoutParams(
       LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT,Gravity.CENTER_VERTICAL + Gravity.CENTER_HORIZONTAL);
    linear.addView(zoomControls, p);
}*/
private void initMyLocation() {
    final MyLocationOverlay overlay = new MyLocationOverlay(this, map);
    overlay.enableMyLocation();
    overlay.enableCompass(); 
    //
    mylocation=overlay.getMyLocation();
    overlay.runOnFirstFix(new Runnable() {
        public void run() {
            controller.setZoom(13);
            controller.animateTo(overlay.getMyLocation());
        }
    });
    map.getOverlays().add(overlay);

    //myLatitude=(overlay.getMyLocation().getLatitudeE6())/1e6;
    //myLongitude=(overlay.getMyLocation().getLongitudeE6())/1e6;

}

}

logcat的：

11-09 13:02:37.480: D/libEGL(26632): loaded /system/lib/egl/libGLES_android.so
11-09 13:02:37.488: D/libEGL(26632): loaded /vendor/lib/egl/libEGL_POWERVR_SGX540_120.so
11-09 13:02:37.488: D/libEGL(26632): loaded /vendor/lib/egl/libGLESv1_CM_POWERVR_SGX540_120.so
11-09 13:02:37.496: D/libEGL(26632): loaded /vendor/lib/egl/libGLESv2_POWERVR_SGX540_120.so
11-09 13:02:37.637: D/OpenGLRenderer(26632): Enabling debug mode 0
11-09 13:02:40.582: D/dalvikvm(26632): GC_CONCURRENT freed 189K, 2% free 14334K/14599K, paused 3ms+2ms
11-09 13:02:40.582: W/CursorWrapperInner(26632): Cursor finalized without prior close()
11-09 13:02:40.691: I/Maps.MyLocationOverlay(26632): Request updates from network
11-09 13:02:40.707: D/dalvikvm(26632): GC_CONCURRENT freed 121K, 2% free 14613K/14855K, paused 2ms+2ms
11-09 13:02:40.855: D/AndroidRuntime(26632): Shutting down VM
11-09 13:02:40.855: W/dalvikvm(26632): threadid=1: thread exiting with uncaught exception (group=0x40a3f1f8)
11-09 13:02:40.855: E/AndroidRuntime(26632): FATAL EXCEPTION: main
11-09 13:02:40.855: E/AndroidRuntime(26632): java.lang.RuntimeException: Unable to start activity ComponentInfo{org.example.loyaltier/org.example.loyaltier.Location}: java.lang.NullPointerException
11-09 13:02:40.855: E/AndroidRuntime(26632):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at android.app.ActivityThread.access$600(ActivityThread.java:122)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at android.os.Handler.dispatchMessage(Handler.java:99)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at android.os.Looper.loop(Looper.java:137)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at android.app.ActivityThread.main(ActivityThread.java:4340)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at java.lang.reflect.Method.invokeNative(Native Method)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at java.lang.reflect.Method.invoke(Method.java:511)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at dalvik.system.NativeStart.main(Native Method)
11-09 13:02:40.855: E/AndroidRuntime(26632): Caused by: java.lang.NullPointerException
11-09 13:02:40.855: E/AndroidRuntime(26632):    at com.google.android.maps.ItemizedOverlay.populate(ItemizedOverlay.java:312)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at org.example.loyaltier.SimpleItemizedOverlay.addOverlay(SimpleItemizedOverlay.java:27)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at org.example.loyaltier.Location.onCreate(Location.java:85)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at android.app.Activity.performCreate (Activity.java:4465)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919)
11-09 13:02:40.855: E/AndroidRuntime(26632):    ... 11 more
11-09 13:02:42.887: I/Process(26632): Sending signal. PID: 26632 SIG: 9
11-09 13:02:37.480: D/libEGL(26632): loaded /system/lib/egl/libGLES_android.so
11-09 13:02:37.488: D/libEGL(26632): loaded /vendor/lib/egl/libEGL_POWERVR_SGX540_120.so
11-09 13:02:37.488: D/libEGL(26632): loaded /vendor/lib/egl/libGLESv1_CM_POWERVR_SGX540_120.so
11-09 13:02:37.496: D/libEGL(26632): loaded /vendor/lib/egl/libGLESv2_POWERVR_SGX540_120.so
11-09 13:02:37.637: D/OpenGLRenderer(26632): Enabling debug mode 0
11-09 13:02:40.582: D/dalvikvm(26632): GC_CONCURRENT freed 189K, 2% free 14334K/14599K, paused 3ms+2ms
11-09 13:02:40.582: W/CursorWrapperInner(26632): Cursor finalized without prior close()
11-09 13:02:40.691: I/Maps.MyLocationOverlay(26632): Request updates from network
11-09 13:02:40.707: D/dalvikvm(26632): GC_CONCURRENT freed 121K, 2% free 14613K/14855K, paused  2ms+2ms
11-09 13:02:40.855: D/AndroidRuntime(26632): Shutting down VM
11-09 13:02:40.855: W/dalvikvm(26632): threadid=1: thread exiting with uncaught exception (group=0x40a3f1f8)
11-09 13:02:40.855: E/AndroidRuntime(26632): FATAL EXCEPTION: main
11-09 13:02:40.855: E/AndroidRuntime(26632): java.lang.RuntimeException: Unable to start activity ComponentInfo{org.example.loyaltier/org.example.loyaltier.Location}: java.lang.NullPointerException
11-09 13:02:40.855: E/AndroidRuntime(26632):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at android.app.ActivityThread.access$600(ActivityThread.java:122)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at android.os.Handler.dispatchMessage(Handler.java:99)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at android.os.Looper.loop(Looper.java:137)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at android.app.ActivityThread.main(ActivityThread.java:4340)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at java.lang.reflect.Method.invokeNative(Native Method)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at java.lang.reflect.Method.invoke(Method.java:511)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at dalvik.system.NativeStart.main(Native Method)
11-09 13:02:40.855: E/AndroidRuntime(26632): Caused by: java.lang.NullPointerException
11-09 13:02:40.855: E/AndroidRuntime(26632):    at com.google.android.maps.ItemizedOverlay.populate(ItemizedOverlay.java:312)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at org.example.loyaltier.SimpleItemizedOverlay.addOverlay(SimpleItemizedOverlay.java:27)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at org.example.loyaltier.Location.onCreate(Location.java:85)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at android.app.Activity.performCreate(Activity.java:4465)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
11-09 13:02:40.855: E/AndroidRuntime(26632):    at  android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919)
11-09 13:02:40.855: E/AndroidRuntime(26632):    ... 11 more
11-09 13:02:42.887: I/Process(26632): Sending signal. PID: 26632 SIG: 9

Answer 1

首先，如果您只是向我们显示错误报告，我们将无法帮助您，您需要显示实际代码。

其次有很多资源可以教你什么是空指针异常，所以你可以调试你的程序，这里是一个：What is a NullPointerException, and how do I fix it?

Answer 2

OverlayItem overlayItem=new OverlayItem(searchLocation,text_location.getText().toString(),"for test");

text_location.getText()一开始就会为空，因为你已将它放在keyListener之外。

尝试输入此代码

mapOverlays=map.getOverlays();
    drawable=getResources().getDrawable(R.drawable.marker);
    itemizedOverlay=new SimpleItemizedOverlay(drawable,map);
    OverlayItem overlayItem=new OverlayItem(searchLocation,text_location.getText().toString(),"for test");
    itemizedOverlay.addOverlay(overlayItem);
    mapOverlays.add(itemizedOverlay);

进入if(keyCode==KeyEvent.KEYCODE_ENTER){区域。

地图应用程序中的nullPointerException错误

2 个答案: