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我想開始說我知道這個錯誤已經發布了大約2000次，但是在瀏覽頁面和頁面上的同一個問題的人並嘗試所有的修復之後，他們都沒有工作，所以我決定提出一個新問題。我很抱歉，如果有針對我的特定問題的解決方案，我無法找到它。java.lang.NullPointerException谷歌地圖Android API V2
因爲這樣，我相信錯誤是MainActivity.Java的第41行有一個NullPointerException，因爲Google Map是null並且沒有被初始化。
41號線如下：
map = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.mapU)).getMap();
如果我刪除所有來自MainActivity.Java我的代碼，只留下由Android Studio生成的代碼時，應用程序啓動了罰款，並顯示谷歌地圖世界，所以我不認爲它與我的API密鑰或Google Play服務沒有任何關係。
一些東西，我已經試過是：
從FragmentManager - 切換到SupportFragmentManager在線41（當我做這個，我改變了地圖從FragmentMap到SupportMapFragment）
-Adding權限清單文件，你可以看到我結束的一切。 - 不同設備
-I原本就minSDK 12（在三星Galaxy S2和銀河S4不工作），決定改變到16只，看它是否會有所幫助，沒有什麼
注：我首先創建了這個項目，出於某種原因，MainActivity.Java表示擴展了ActionBarActivity而不是FragmentActivity，所以我將其改爲說FragmentActivity，但我之前和之後都遇到了這個問題。
的Manifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.hasan.maps" >
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"></uses-permission>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
<uses-permission android:name="com.google.android.providers.gsf.permission.MAPS_RECIEVE"></uses-permission>
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES"/>
<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" >
<activity
android:name="com.hasan.maps.MainActivity"
android:label="@string/app_name"
>
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<meta-data
android:name="com.google.android.maps.v2.API_KEY"
android:value="APIKEY_IS_INSERTED_HERE"/>
<meta-data
android:name="com.google.android.gms.version"
android:value="@integer/google_play_services_version" />
</application>
</manifest>
MainActivity.Java
package com.hasan.maps;
import android.support.v4.app.FragmentActivity;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;
import com.google.android.gms.maps.CameraUpdate;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapFragment;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
public class MainActivity extends FragmentActivity {
private GoogleMap map;
private final LatLng Location_NJIT = new LatLng(40.7406517, -74.1792757);
private final LatLng Location_Stevens = new LatLng(40.7469309, -74.0258336);
@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();
}
map = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.mapU)).getMap();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public void onClick_city (View v){
}
public void onClick_njit (View v){
CameraUpdate update = CameraUpdateFactory.newLatLng(Location_NJIT);
map.animateCamera(update);
}
public void onClick_stevens (View v){
}
/**
* 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;
}
}
}
logcat的
Logcat
01-31 00:08:42.050 14353-14353/com.hasan.maps E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.hasan.maps/com.hasan.maps.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2110)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2135)
at android.app.ActivityThread.access$700(ActivityThread.java:140)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1237)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4938)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
atcom.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.hasan.maps.MainActivity.onCreate(MainActivity.java:41)
at android.app.Activity.performCreate(Activity.java:5188)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2074)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2135)
at android.app.ActivityThread.access$700(ActivityThread.java:140)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1237)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4938)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
Fragment_Main.xml
<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"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context="com.hasan.maps.MainActivity$PlaceholderFragment">
<fragment
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/mapU"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_below="@+id/stevens" />
<Button
style="?android:attr/buttonStyleSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="City"
android:id="@+id/city"
android:layout_above="@+id/map"
android:layout_toRightOf="@+id/header"
android:onClick="onClick_city" />
<Button
style="?android:attr/buttonStyleSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="NJIT"
android:id="@+id/njit"
android:layout_alignParentTop="true"
android:layout_toRightOf="@+id/city"
android:onClick="onClick_njit" />
<Button
style="?android:attr/buttonStyleSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Stevens"
android:id="@+id/stevens"
android:layout_alignParentTop="true"
android:layout_toRightOf="@+id/njit"
android:onClick="onClick_stevens" />
</RelativeLayout>
提前致謝！
MainActivity.java第41行的內容是什麼？ –
對不起，我應該指定map =（（SupportMapFragment）getSupportFragmentManager（）。findFragmentById（R.id.mapU））。getMap（）; – user2828960