今天，我的Eclipse崩溃了。因此，我重新创建了我的项目。
我没有更改代码，但它无法正常工作。
问题是当我使用SupportMapFragment getMap（）函数时，我得到了一个
显示java.lang.NullPointerException。
很奇怪，因为它在我重新创建项目之前工作正常。代码如下所示：
public class MapFragment extends Fragment {
private static GoogleMap mMap;
private LocationManager locationManager;
private LocationListener locationListener;
private String mUserName;
private final static int DAY = 0;
private final static int MONTH = 1;
private final static int YEAR = 2;
private long timeFrom, timeTo, now;
private Button btnTimeChanger;
private int postion = 2;
private View view;
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
LayoutParams params = new LayoutParams(LayoutParams.MATCH_PARENT,
LayoutParams.MATCH_PARENT);
FrameLayout fl = new FrameLayout(getActivity());
fl.setLayoutParams(params);
DisplayMetrics dm = getResources().getDisplayMetrics();
final int margin = (int) TypedValue.applyDimension(
TypedValue.COMPLEX_UNIT_DIP, 8, dm);
view = inflater.inflate(R.layout.mapdisplay, container, false);
int status = GooglePlayServicesUtil
.isGooglePlayServicesAvailable(getActivity().getBaseContext());
if (status != ConnectionResult.SUCCESS) { // Google Play Services are
// not available
int requestCode = 10;
Dialog dialog = GooglePlayServicesUtil.getErrorDialog(status,
getActivity(), requestCode);
dialog.show();
} else { // Google Play Services are available
view = initializeMap(view);
TextView v = new TextView(getActivity());
params.setMargins(margin, margin, margin, margin);
v.setLayoutParams(params);
v.setGravity(Gravity.CENTER);
v.setText("Google Map");
v.setTextSize((int) TypedValue.applyDimension(
TypedValue.COMPLEX_UNIT_SP, 12, dm));
fl.addView(view);
fl.addView(v);
return fl;
}
private View initializeMap(View v) { // TODO Auto-generated method stub
SupportMapFragment fm = (SupportMapFragment) getActivity()
.getSupportFragmentManager().findFragmentById(R.id.google_map);
// Getting GoogleMap object from the fragment
mMap = fm.getMap();
mMap.setMyLocationEnabled(true);
RadioGroup rgViews = (RadioGroup) v.findViewById(R.id.rg_views);
rgViews.setOnCheckedChangeListener(new OnCheckedChangeListener() {
@Override public void onCheckedChanged(RadioGroup group, int checkedId) {
if (checkedId == R.id.rb_map) {
mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
} else if (checkedId == R.id.rb_satellite) {
mMap.setMapType(GoogleMap.MAP_TYPE_SATELLITE);
} } });
btnTimeChanger = (Button) v.findViewById(R.id.btnTimechanger); btnTimeChanger.setText("Time"); btnTimeChanger.setTextSize(12); btnTimeChanger.setHeight(13); btnTimeChanger.setWidth(20);
return v;
}
相应的MapFragment视图xml文件：
<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" >
<RadioGroup
android:id="@+id/rg_views"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center_horizontal"
android:orientation="horizontal" >
<RadioButton
android:id="@+id/rb_map"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/str_rb_map"
android:checked="true" />
<RadioButton
android:id="@+id/rb_satellite"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/str_rb_satellite" />
</RadioGroup>
<Button
android:id="@+id/btnTimechanger"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
<fragment
android:id="@+id/google_map"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="@id/rg_views"
class="com.google.android.gms.maps.SupportMapFragment" />
</RelativeLayout>
当我运行应用程序时，它会显示如下的异常：
10-23 21:09:32.426: D/AndroidRuntime(10159): Shutting down VM
10-23 21:09:32.426: W/dalvikvm(10159): threadid=1: thread exiting with uncaught exception (group=0x4208ac08)
10-23 21:09:32.441: E/AndroidRuntime(10159): FATAL EXCEPTION: main
10-23 21:09:32.441: E/AndroidRuntime(10159): Process: com.facebook.biodatashare, PID: 10159
10-23 21:09:32.441: E/AndroidRuntime(10159): java.lang.NullPointerException
10-23 21:09:32.441: E/AndroidRuntime(10159): at com.facebook.biodatashare.display.MapFragment.initializeMap(MapFragment.java:244)
10-23 21:09:32.441: E/AndroidRuntime(10159): at com.facebook.biodatashare.display.MapFragment.onCreateView(MapFragment.java:93)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.support.v4.app.Fragment.performCreateView(Fragment.java:1786)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:947)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1126)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:739)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1489)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:486)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.support.v4.view.ViewPager.populate(ViewPager.java:1073)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.support.v4.view.ViewPager.populate(ViewPager.java:919)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1441)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.view.View.measure(View.java:17387)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:719)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:455)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.view.View.measure(View.java:17387)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5352)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.view.View.measure(View.java:17387)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5352)
10-23 21:09:32.441: E/AndroidRuntime(10159): at com.android.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:391)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.view.View.measure(View.java:17387)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5352)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
10-23 21:09:32.441: E/AndroidRuntime(10159): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2533)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.view.View.measure(View.java:17387)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2213)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1350)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1549)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1234)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6467)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:803)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.view.Choreographer.doCallbacks(Choreographer.java:603)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.view.Choreographer.doFrame(Choreographer.java:573)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:789)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.os.Handler.handleCallback(Handler.java:733)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.os.Handler.dispatchMessage(Handler.java:95)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.os.Looper.loop(Looper.java:157)
10-23 21:09:32.441: E/AndroidRuntime(10159): at android.app.ActivityThread.main(ActivityThread.java:5356)
10-23 21:09:32.441: E/AndroidRuntime(10159): at java.lang.reflect.Method.invokeNative(Native Method)
10-23 21:09:32.441: E/AndroidRuntime(10159): at java.lang.reflect.Method.invoke(Method.java:515)
10-23 21:09:32.441: E/AndroidRuntime(10159): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
10-23 21:09:32.441: E/AndroidRuntime(10159): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
10-23 21:09:32.441: E/AndroidRuntime(10159): at dalvik.system.NativeStart.main(Native Method)
10-23 21:09:32.476: D/dalvikvm(10159): GC_FOR_ALLOC freed 1169K, 24% free 21999K/28880K, paused 31ms, total 31ms
10-23 21:09:32.486: D/REQUEST(10159): Processing DataRequest: com.google.maps.api.android.lib6.b.d@432a7518
10-23 21:09:32.486: D/REQUEST(10159): Processing DataRequest: com.google.maps.api.android.lib6.c.au@43296960
10-23 21:09:32.486: D/REQUEST(10159): DRD(1): 62|147, <1s, <1kb
10-23 21:09:32.486: D/REQUEST(10159): Close
10-23 21:09:32.486: D/USER_EVENTS(10159): Event: type=22, status: fb, data: 66
10-23 21:09:32.491: D/USER_EVENTS(10159): Event: type=22, status: lb, data: 67
10-23 21:09:32.491: D/USER_EVENTS(10159): Event: type=22, status: flbs, data: fb=66|lb=67|s=16
这是该项目的清单文件：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.facebook.biodatashare"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="14"
android:targetSdkVersion="19" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />
<!--
The following two permissions are not required to use
Google Maps Android API v2, but are recommended.
-->
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-feature
android:glEsVersion="0x00020000"
android:required="true" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<meta-data
android:name="com.google.android.gms.version"
android:value="@integer/google_play_services_version" />
<meta-data
android:name="com.google.android.maps.v2.API_KEY"
android:value="AIzaSyCq7IeRF5UsyGEsFhq_mL538oSLy4tsk20" />
<activity
android:name="com.yixian.biodatashare.LoginActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="com.facebook.LoginActivity"
android:label="@string/app_name" >
</activity>
<activity
android:name="com.yixian.biodatashare.DataSelectActivity"
android:label="@string/app_name" >
</activity>
<activity
android:name="com.yixian.biodatashare.TimeSelectionActivity"
android:label="@string/app_name" >
</activity>
<activity
android:name="com.facebook.biodatashare.display.DisplayActivity"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
</activity>
<meta-data
android:name="com.facebook.sdk.ApplicationId"
android:value="@string/app_id" />
</application>
</manifest>
MapFragment来自FragmentActivity：我使用了下载的PagerSlidingTabStrip
来自https://github.com/astuetz/PagerSlidingTabStrip：
public class DisplayActivity extends FragmentActivity {
private MapFragment mapFragment;
/**
* MapFragment
*/
private DataAnalysisFragment dataAnalysisFragment;
/**
* DataAnalysisFragment
*/
/**
* The instance of PagerSlidingTabStrip
*/
private PagerSlidingTabStrip tabs;
/**
* Obtain the metrics of the screen
*/
private DisplayMetrics dm;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.display);
setOverflowShowingAlways();
dm = getResources().getDisplayMetrics();
ViewPager pager = (ViewPager) findViewById(R.id.pager);
tabs = (PagerSlidingTabStrip) findViewById(R.id.tabs);
pager.setAdapter(new MyPagerAdapter(getSupportFragmentManager()));
tabs.setViewPager(pager);
setTabsValue();
}
/**
* 对PagerSlidingTabStrip的各项属性进行赋值。
*/
private void setTabsValue() {
tabs.setShouldExpand(true);
tabs.setDividerColor(Color.TRANSPARENT);
tabs.setUnderlineHeight((int) TypedValue.applyDimension(
TypedValue.COMPLEX_UNIT_DIP, 1, dm));
tabs.setIndicatorHeight((int) TypedValue.applyDimension(
TypedValue.COMPLEX_UNIT_DIP, 4, dm));
tabs.setTextSize((int) TypedValue.applyDimension(
TypedValue.COMPLEX_UNIT_SP, 16, dm));
tabs.setIndicatorColor(Color.parseColor("#45c01a"));
tabs.setSelectedTextColor(Color.parseColor("#45c01a"));
tabs.setTabBackground(0);
}
public class MyPagerAdapter extends FragmentPagerAdapter {
public MyPagerAdapter(FragmentManager fm) {
super(fm);
}
private final String[] titles = { "Map", "Data Analysis"};
@Override
public CharSequence getPageTitle(int position) {
return titles[position];
}
@Override
public int getCount() {
return titles.length;
}
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
if (mapFragment == null) {
mapFragment = new MapFragment();
}
return mapFragment;
case 1:
if (dataAnalysisFragment == null) {
dataAnalysisFragment = new DataAnalysisFragment();
}
return dataAnalysisFragment;
default:
return null;
}
}
}
public void showDialog()
{
final CharSequence[] items={"Map","Chart","Both of them"};
AlertDialog.Builder builder=new AlertDialog.Builder(this);
builder.setTitle("Which presentation will be shared on facebook?");
builder.setPositiveButton("ok", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
builder.setSingleChoiceItems(items,-1, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
if("Red".equals(items[which]))
{
}
else if("Green".equals(items[which]))
{
}
else if("Blue".equals(items[which]))
{
}
}
});
builder.show();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onMenuOpened(int featureId, Menu menu) {
if (featureId == Window.FEATURE_ACTION_BAR && menu != null) {
if (menu.getClass().getSimpleName().equals("MenuBuilder")) {
try {
Method m = menu.getClass().getDeclaredMethod(
"setOptionalIconsVisible", Boolean.TYPE);
m.setAccessible(true);
m.invoke(menu, true);
} catch (Exception e) {
}
}
}
return super.onMenuOpened(featureId, menu);
}
private void setOverflowShowingAlways() {
try {
ViewConfiguration config = ViewConfiguration.get(this);
Field menuKeyField = ViewConfiguration.class
.getDeclaredField("sHasPermanentMenuKey");
menuKeyField.setAccessible(true);
menuKeyField.setBoolean(config, false);
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.action_album:
showDialog();
Toast.makeText(this, "Action Refresh selected", Toast.LENGTH_SHORT).show();
break;
default:
break;
}
return true;
}
}
FragmentActivity的XML：
<?xml version="1.0" encoding="utf-8"?>
<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" >
<com.yixian.biodataintegration.PagerSlidingTabStrip
android:id="@+id/tabs"
android:layout_width="match_parent"
android:layout_height="40dp" />
<android.support.v4.view.ViewPager
android:id="@+id/pager"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/tabs" />
</RelativeLayout>
谁能帮我解决问题？
答案 0 :(得分：14)
尝试更改此代码块：
SupportMapFragment fm = (SupportMapFragment) getActivity()
.getSupportFragmentManager().findFragmentById(R.id.google_map);
// Getting GoogleMap object from the fragment
mMap = fm.getMap();
为：
GoogleMap mMap = ((SupportMapFragment) this.getChildFragmentManager().findFragmentById(R.id.google_map)).getMap();
答案 1 :(得分：1)
试试这个......
private GoogleMap googleMap;
private SupportMapFragment mapFragment;
......
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup viewGroup, Bundle bundle) {
.......
FragmentManager fManager= getChildFragmentManager();
mapFragment = (SupportMapFragment) fManager
.findFragmentById(R.id.ezeidHomeMap);
mapFragment.getMapAsync(new OnMapReadyCallback()
{
public void onMapReady(GoogleMap map)
{
if (map == null)
{
// showToast(getActivity(),
"Sorry! unable to create maps");
} else
{
googleMap = map;
googleMap.getUiSettings().setCompassEnabled(true);
googleMap.getUiSettings().setZoomControlsEnabled(true);
googleMap.getUiSettings().setMyLocationButtonEnabled(false);
googleMap.getUiSettings().setRotateGesturesEnabled(true);
}
}
});
.......
}
答案 2 :(得分：0)
((SupportMapFragment) this.getChildFragmentManager().findFragmentById(R.id.google_map)).getMapAsync(this);
不要忘记实现以下回调：
@Override
public void onMapReady(GoogleMap googleMap) {
}