Android 配置 之 AndroidManifest.xml 出错 Unable to instantiate activity ComponentInfo

在尝试启动Android应用时遇到了'Unable to instantiate activity ComponentInfo'异常,错误指出无法找到类'com.example.demo.GestureEvent'。问题可能出在AndroidManifest.xml中配置的activity名称不正确。确保<activity>标签中的android:name属性值为全路径且正确,例如'com.zouxiaojia.tabtest.MainActivity'。如果配置错误,应用会抛出ClassNotFoundException。

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04-08 18:17:48.468: ERROR/AndroidRuntime(20955): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example/com.example.demo.GestureEvent}:java.lang.ClassNotFoundException: com.example.demo.GestureEvent in loader dalvik.system.PathClassLoader@4485c9a8

04-08 18:17:48.468: ERROR/AndroidRuntime(20955):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2497)


我的AndroidManifest.xml文件

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.zouxiaojia.tabtest"
    android:versionCode="1"
    android:versionName="1.0" >
    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="16" />
    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.zouxiaojia.tabtest.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>
    </application>
</manifest>

关键代码

<activity android:name="com.zouxiaojia.tabtest.MainActivity">

android:name 需要配置正确,而且为全路径 路径为.tabtest.TabTest仍会报错

<activity android:name="com.zouxiaojia.tabtest.TabTest">

 

否则将会抛出如上异常



分析以下报错信息: E FATAL EXCEPTION: main Process: com.example.contacts2, PID: 11798 java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.contacts2/com.example.contacts2.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:4186) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:4467) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:222) at android.app.servertransaction.TransactionExecutor.executeNonLifecycleItem(TransactionExecutor.java:133) at android.app.servertransaction.TransactionExecutor.executeTransactionItems(TransactionExecutor.java:103) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:80) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2823) at android.os.Handler.dispatchMessage(Handler.java:110) at android.os.Looper.loopOnce(Looper.java:248) at android.os.Looper.loop(Looper.java:338) at android.app.ActivityThread.main(ActivityThread.java:9067) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:593) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:932) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()' on a null object reference at android.content.ContextWrapper.getApplicationInfo(ContextWrapper.java:208) at android.view.ContextThemeWrapper.getTheme(ContextThemeWrapper.java:174) at android.content.Context.obtainStyledAttributes(Context.java:1103) at androidx.appcompat.app.AppCompatDelegateImpl.createSubDecor(AppCompatDelegateImpl.java:922) at androidx.appcompat.app.AppCompatDelegateImpl.ensureSubDecor(AppCompatDelegateImpl.java:889) at androidx.appcompat.app.AppCompatDelegateImpl.findViewById(AppCompatDelegateImpl.java:691) at androidx.appcompat.app.AppCompatActivity.findViewById(AppCompatActivity.java:264) at com.example.contacts2.MainActivity.<init>(MainActivity.java:35) at java.lang.Class.newInstance(Native Method) at android.app.AppComponentFactory.instantiateActivity(AppComponentFactory.java:95) at androidx.core.app.CoreComponentFactory.instantiateActivity(CoreComponentFactory.java:45) at android.app.Instrumentation.newActivity(Instrumentation.java:1443) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:4173) ... 13 more
07-23
分析以下报错; FATAL EXCEPTION: main Process: com.example.contacts2, PID: 12148 java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.contacts2/com.example.contacts2.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:4186) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:4467) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:222) at android.app.servertransaction.TransactionExecutor.executeNonLifecycleItem(TransactionExecutor.java:133) at android.app.servertransaction.TransactionExecutor.executeTransactionItems(TransactionExecutor.java:103) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:80) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2823) at android.os.Handler.dispatchMessage(Handler.java:110) at android.os.Looper.loopOnce(Looper.java:248) at android.os.Looper.loop(Looper.java:338) at android.app.ActivityThread.main(ActivityThread.java:9067) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:593) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:932) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()' on a null object reference at android.content.ContextWrapper.getApplicationInfo(ContextWrapper.java:208) at android.view.ContextThemeWrapper.getTheme(ContextThemeWrapper.java:174) at android.content.Context.obtainStyledAttributes(Context.java:1103) at androidx.appcompat.app.AppCompatDelegateImpl.createSubDecor(AppCompatDelegateImpl.java:922) at androidx.appcompat.app.AppCompatDelegateImpl.ensureSubDecor(AppCompatDelegateImpl.java:889) at androidx.appcompat.app.AppCompatDelegateImpl.findViewById(AppCompatDelegateImpl.java:691) at androidx.appcompat.app.AppCompatActivity.findViewById(AppCompatActivity.java:264) at com.example.contacts2.MainActivity.<init>(MainActivity.java:36) at java.lang.Class.newInstance(Native Method) at android.app.AppComponentFactory.instantiateActivity(AppComponentFactory.java:95) at androidx.core.app.CoreComponentFactory.instantiateActivity(CoreComponentFactory.java:45) at android.app.Instrumentation.newActivity(Instrumentation.java:1443) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:4173) ... 13 more
07-23
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