问题描述
我正在按照本教程制作导航抽屉：
我的片段之一是定义如下的地图：
XML格式
<fragment android:id="@+id/map"
android:layout_width="match_parent"
android:layout_height="match_parent"
class="com.google.android.gms.maps.MapFragment" />
<FrameLayout android:orientation="vertical" xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
/*Some texts and buttons */
</FrameLayout>
</RelativeLayout>
爪哇
public class MapsFragment extends Fragment implements AsyncResponse {
private View mView;
private GoogleMap mMap;
private LayoutInflater mInflater;
private Bundle savedInstanceState;
private CustomButton mCancelButton;
private CustomButton mPeekButton;
private boolean mActivityPaused;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
mPeeks = new ArrayList();
mGson = new Gson();
mInflater = inflater;
mIsPaneOpen = false;
mMarkerMap = new HashMap();
if (mView != null) {
ViewGroup parent = (ViewGroup) mView.getParent();
if (parent != null)
parent.removeView(mView);
}
try {
mView = mInflater.inflate(R.layout.activity_maps, container, false);
} catch (InflateException e) {
e.printStackTrace();
}
setUpMapIfNeeded();
mCancelButton = (CustomButton) mView.findViewById(R.id.bt_cancel);
return mView;
}
public void setUpMapIfNeeded(){
if (mMap == null){
mMap = ((MapFragment) getActivity().getFragmentManager().findFragmentById(R.id.map)).getMap();
if (mMap != null)
setUpMap();
}
}
private void setUpMap() {
mMap.setMyLocationEnabled(true);
//Some code
}
}
我自愿删除了一些不相关的代码。 然后我有主要活动：
XML格式
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<!-- The ActionBar -->
<include
layout="@layout/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<!-- The main content view -->
<FrameLayout
android:id="@+id/flContent"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
<!-- The navigation drawer -->
<android.support.design.widget.NavigationView
android:id="@+id/nvView"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:background="@android:color/white"
app:menu="@menu/drawer_view" />
</android.support.v4.widget.DrawerLayout>
</LinearLayout>
爪哇
public class MainActivity extends AppCompatActivity {
/**
* Fragment managing the behaviors, interactions and presentation of the navigation drawer.
*/
//Manager de Fragment
DrawerLayout mDrawer; // Declaring DrawerLayout
Toolbar mToolbar;
Fragment currentFrag;
FragmentManager mFragmentManager;
Fragment mMapFragment;
Fragment mUserFragment;
Fragment mThirdFragment;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mFragmentManager = getSupportFragmentManager();
mMapFragment = new MapsFragment();
mUserFragment = new UserFragment();
mThirdFragment = new ThirdFragment();
//Initializing the first Fragment
mFragmentManager.beginTransaction().replace(R.id.flContent, new MapsFragment()).commit();
// Set a Toolbar to replace the ActionBar.
mToolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(mToolbar);
// Find our drawer view
mDrawer = (DrawerLayout) findViewById(R.id.drawer_layout);
// Set the menu icon instead of the launcher icon.
final ActionBar ab = getSupportActionBar();
ab.setHomeAsUpIndicator(R.drawable.ic_menu);
ab.setDisplayHomeAsUpEnabled(true);
// Find our drawer view
NavigationView nvDrawer = (NavigationView) findViewById(R.id.nvView);
// Setup drawer view
setupDrawerContent(nvDrawer);
}
//First We Declare Titles And Icons For Our Navigation Drawer List View
//This Icons And Titles Are holded in an Array as you can see
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// The action bar home/up action should open or close the drawer.
switch (item.getItemId()) {
case android.R.id.home:
mDrawer.openDrawer(GravityCompat.START);
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
}
private void setupDrawerContent(NavigationView navigationView) {
navigationView.setNavigationItemSelectedListener(
new NavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(MenuItem menuItem) {
selectDrawerItem(menuItem);
return true;
}
});
}
public void selectDrawerItem(MenuItem menuItem) {
// Create a new fragment and specify the planet to show based on
// position
Fragment fragment = null;
switch(menuItem.getItemId()) {
case R.id.nav_map:
fragment = mMapFragment;
break;
case R.id.nav_profile:
fragment = mUserFragment;
break;
case R.id.nav_nav_settings:
fragment = mThirdFragment;
break;
default:
fragment = mMapFragment;
}
// Insert the fragment by replacing any existing fragment
mFragmentManager.beginTransaction().replace(R.id.flContent, fragment).commit();
// Highlight the selected item, update the title, and close the drawer
menuItem.setChecked(true);
setTitle(menuItem.getTitle());
mDrawer.closeDrawers();
}
}
问题是，当我第一次附加de MapFragment时，没问题，活动将显示地图。 但是，当我尝试通过导航抽屉转到另一个片段，然后又回到地图片段时，我遇到了以下异常：
07-19 16:04:25.710 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ android.view.InflateException: Binary XML file line #12: Error inflating class fragment
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:770)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at android.view.LayoutInflater.rInflate(LayoutInflater.java:813)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at android.view.LayoutInflater.inflate(LayoutInflater.java:511)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at android.view.LayoutInflater.inflate(LayoutInflater.java:415)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at fr.yougraph.homelesspasseul.fragment.MapsFragment.onCreateView(MapsFragment.java:93)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at android.support.v4.app.Fragment.performCreateView(Fragment.java:1789)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:955)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1138)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:740)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1501)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:458)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at android.os.Handler.handleCallback(Handler.java:739)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at android.os.Handler.dispatchMessage(Handler.java:95)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at android.os.Looper.loop(Looper.java:145)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at android.app.ActivityThread.main(ActivityThread.java:5944)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at java.lang.reflect.Method.invoke(Native Method)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at java.lang.reflect.Method.invoke(Method.java:372)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1389)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1184)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ Caused by: java.lang.IllegalArgumentException: Binary XML file line #12: Duplicate id 0x7f0e0099, tag null, or parent id 0x7f0e0098 with another fragment for com.google.android.gms.maps.MapFragment
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at android.app.FragmentManagerImpl.onCreateView(FragmentManager.java:2135)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at android.app.Activity.onCreateView(Activity.java:5610)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at android.support.v7.app.AppCompatDelegateImplV11.callActivityOnCreateView(AppCompatDelegateImplV11.java:41)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at android.support.v7.app.AppCompatDelegateImplV7.onCreateView(AppCompatDelegateImplV7.java:826)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at android.support.v4.view.LayoutInflaterCompatHC$FactoryWrapperHC.onCreateView(LayoutInflaterCompatHC.java:44)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at android.view.LayoutInflater$FactoryMerger.onCreateView(LayoutInflater.java:181)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:732)
07-19 16:04:25.720 12380-12380/fr.yougraph.homelesspasseul W/System.err﹕ ... 18 more
07-19 16:04:25.740 12380-12380/fr.yougraph.homelesspasseul D/AndroidRuntime﹕ Shutting down VM
07-19 16:04:25.740 12380-12380/fr.yougraph.homelesspasseul E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: fr.yougraph.homelesspasseul, PID: 12380
java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference
at fr.yougraph.homelesspasseul.fragment.MapsFragment.onCreateView(MapsFragment.java:123)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1789)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:955)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1138)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:740)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1501)
at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:458)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:5944)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1389)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1184)
第一个例外，由于重复的mapfragment，导致mView为null，而我无法执行findViewById。
我看不到我在哪里错，我以前使用过寻呼机条，并且片段之间的切换效果很好，因此就像地图一样。
谢谢你的帮助
顺便说一下，我尝试了这些问题中给出的解决方案：
没有工作
1楼
我认为重复项来自：在MainActivity的onCreated中，您调用setupDrawerContent，它调用selectDrawerItem，默认情况下会设置片段= mMapfragment，但以前在Oncreate中，您已经在此行中创建了另一个MapsFragment：
- mFragmentManager.beginTransaction（）。replace（R.id.flContent，new MapsFragment（））。commit（）;
所以我的建议是尝试将初始化更改为您已经声明的mMapFragment：
- mFragmentManager.beginTransaction（）。replace（R.id.flContent，mMapFragment）.commit（）;