当我尝试通过意图调用新活动时,出现错误:
java.lang.NullPointerException: Attempt to invoke virtual method 'android.app.ActivityThread$ApplicationThread android.app.ActivityThread.getApplicationThread()' on a null object reference
我的活动有一个按钮,点击它会进入这个方法:
public void onClickChangeActivity() {
Intent intent = new Intent(context , Details.class);
startActivity(intent);
}
在类的开头创建 public static Context context,然后在我的 onCreate 中进行实例化 context = getApplicationContext()。
我也尝试过 context = getBaseContext() 和 context = RecyclerViewActivity.this(RecyclerViewActivity 是当前类的名称)
为什么我收到 NullP 的帮助?我已经尝试了 StackOverFlow 提供的所有相关答案。另外,我的清单包括我的活动。
onClickChangeActivity 是从我的 RecyclerViewerAdapter 类中调用的:
View.OnClickListener getPersonClickListener(final int position) {
return new View.OnClickListener() {
@Override
public void onClick(View view) {
RecyclerViewActivity recyclerViewActivity = new RecyclerViewActivity();
recyclerViewActivity.onClickChangeActivity();
}
};
清单文件:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.test.akash.android_test" >
<uses-sdk
android:minSdkVersion="16"
android:targetSdkVersion="21" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission
android:name="android.permission.WRITE_EXTERNAL_STORAGE"
android:maxSdkVersion="18" />
<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission
android:name="android.permission.READ_EXTERNAL_STORAGE"
android:maxSdkVersion="18" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="@string/app_name"
android:screenOrientation="portrait" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<!-- <activity -->
<!-- android:name=".DataFetcher" -->
<!-- android:label="@string/title_activity_data_fetcher" > -->
<!-- </activity> -->
<activity
android:name=".Crime"
android:label="@string/title_activity_crime"
android:screenOrientation="portrait" >
</activity>
<activity
android:name=".RecyclerViewActivity"
android:label="@string/title_activity_recycler_view"
android:screenOrientation="portrait" >
</activity>
<activity
android:name=".Details"
android:label="@string/title_activity_crime_details"
android:parentActivityName=".RecyclerViewActivity" >
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="RecyclerViewActivity" />
</activity>
</application>
</manifest>
日志记录器:
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference
at android.content.ContextWrapper.getPackageName(ContextWrapper.java:132)
at android.content.ComponentName.<init>(ComponentName.java:77)
at android.content.Intent.<init>(Intent.java:4160)
at com.bah.baltimoreopendata.android_baltimoreopendata.RecyclerViewActivity.onClickChangeActivity(RecyclerViewActivity.java:265)
at com.bah.baltimoreopendata.android_baltimoreopendata.RecycleViewAdapter$1.onClick(RecycleViewAdapter.java:121)
at android.view.View.performClick(View.java:4780)
at android.view.View$PerformClick.run(View.java:19866)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
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:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)