java在SupportFragmentManager上获取GoogleMaps NullPointerException
我试图制作一个使用谷歌地图的应用程序,但我在一开始就添加了一个NullPointerException
如果我在没有GoogleMaps myMap变量的情况下运行这个应用程序,我可以正确地看到地图,但我想处理我的地图,只是无法理解我的代码有什么问题。多谢各位
Java类:
package com.runrabbit.roman.runrabbit_1;
import 安卓.support.v4.app.FragmentActivity;
import 安卓.os.Bundle;
import 安卓.view.Menu;
import 安卓.view.MenuItem;
import com.google.安卓.gms.maps.GoogleMap;
import com.google.安卓.gms.maps.OnMapReadyCallback;
import com.google.安卓.gms.maps.SupportMapFragment;
public class homeActivity extends FragmentActivity implements OnMapReadyCallback {
private GoogleMap myMap;
private SupportMapFragment supportMapFrag;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
myMap = ((SupportMapFragment)getSupportFragmentManager().findFragmentById(R.id.mymap)).getMap();
}
XML文件:
<RelativeLayout xmlns:安卓="http://schemas.安卓.com/apk/res/安卓"
xmlns:tools="http://schemas.安卓.com/tools"
安卓:layout_width="match_parent"
安卓:layout_height="match_parent"
tools:context=".homeActivity">
<TextView
安卓:layout_width="wrap_content"
安卓:layout_height="wrap_content"
安卓:text="MY MAP"
安卓:gravity="center"
安卓:id="@+id/mymap"/>
<fragment
class="com.google.安卓.gms.maps.SupportMapFragment"
安卓:layout_width="match_parent"
安卓:layout_height="180dp"
tools:layout="@layout/activity_home"
安卓:layout_below="@id/mymap"/>
</RelativeLayout>
清单文件:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:安卓="http://schemas.安卓.com/apk/res/安卓"
package="com.runrabbit.roman.runrabbit_1" >
<uses-permission 安卓:name="安卓.permission.INTERNET"/>
<uses-permission 安卓:name="安卓.permission.ACCESS_NETWORK_STATE"/>
<uses-permission 安卓:name="安卓.permission.WRITE_EXTERNAL_STORAGE"/>
<!-- The following two permissions are not required to use
Google Maps Android API v2, but are recommended. -->
<uses-permission 安卓:name="安卓.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission 安卓:name="安卓.permission.ACCESS_FINE_LOCATION"/>
<uses-feature
安卓:glEsVersion="0x00020000"
安卓:required="true"/>
<application
安卓:allowBackup="true"
安卓:icon="@mipmap/ic_launcher"
安卓:label="@string/app_name"
安卓:theme="@style/AppTheme" >
<meta-data
安卓:name="com.google.安卓.geo.API_KEY"
安卓:value="AIzaSyCaka9TmwvXBjk1bDzIbRfDSFniqDwEByg"/>
<activity
安卓:name=".homeActivity"
安卓:label="@string/app_name" >
<intent-filter>
<action 安卓:name="安卓.intent.action.MAIN" />
<category 安卓:name="安卓.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
构建渐变:
apply plugin: 'com.安卓.application'
安卓 {
compileSdkVersion 21
buildToolsVersion "21.1.2"
defaultConfig {
applicationId "com.runrabbit.roman.runrabbit_1"
minSdkVersion 11
targetSdkVersion 21
versionCode 1
versionName "1.0"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-安卓.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
compile 'com.安卓.support:appcompat-v7:22.1.1'
compile 'com.google.安卓.gms:play-services:6.5.87'
}
日志:
Caused by: java.lang.NullPointerException
at com.runrabbit.roman.runrabbit_1.homeActivity.onCreate(homeActivity.java:33)
at 安卓.app.Activity.performCreate(Activity.java:5133)
at 安卓.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at 安卓.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
at 安卓.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
at 安卓.app.ActivityThread.access$600(ActivityThread.java:141)
at 安卓.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
at 安卓.os.Handler.dispatchMessage(Handler.java:99)
at 安卓.os.Looper.loop(Looper.java:137)
at 安卓.app.ActivityThread.main(ActivityThread.java:5103)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.安卓.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
at com.安卓.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
# 1 楼答案
您的片段需要一个ID。您还应该将文本视图更改为其他名称。尝试将布局文件的内容更改为: