今天試用了下Volley框架,運行時老師報這個錯,鬱悶了一會兒才發現,原來是在清單文件裏面沒有聲明,擦
12-23 10:57:07.023 20997-20997/? E/AndroidRuntime: FATAL EXCEPTION: mainjava.lang.RuntimeException: Unable to start activity ComponentInfo{com.cisetech.hello/com.cisetech.hello.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2250)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2304)
at android.app.ActivityThread.access$700(ActivityThread.java:152)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1284)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:176)
at android.app.ActivityThread.main(ActivityThread.java:5299)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.cisetech.hello.MainActivity.volley_get(MainActivity.java:44)at com.cisetech.hello.MainActivity.onCreate(MainActivity.java:22)
at android.app.Activity.performCreate(Activity.java:5326)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1097)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2213)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2304)
at android.app.ActivityThread.access$700(ActivityThread.java:152)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1284)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:176)
at android.app.ActivityThread.main(ActivityThread.java:5299)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
at dalvik.system.NativeStart.main(Native Method)
解決方法:[別忘記加權限]
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.cisetech.hello">
<span style="white-space:pre"> </span><uses-permission android:name="android.permission.INTERNET"></uses-permission>
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
<h3> <span style="color:#ff0000;"> android:name=".MyApplication"</span></h3> android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>