1. 首先我們二話不說直接先看報錯內容如下：

07-12 08:25:03.572: E/dalvikvm(3602): native fork pid:0 done. 07-12 08:25:03.582: E/dalvikvm(3602): threadid=6: created from interp,name=ReferenceQueueDaemon 07-12 08:25:03.582: E/dalvikvm(3602): threadid=6: calling run(),name=ReferenceQueueDaemon 07-12 08:25:03.582: E/dalvikvm(3602): threadid=7: created from interp,name=FinalizerDaemon 07-12 08:25:03.582: E/dalvikvm(3602): threadid=7: calling run(),name=FinalizerDaemon 07-12 08:25:03.592: E/dalvikvm(3602): threadid=8: created from interp,name=FinalizerWatchdogDaemon 07-12 08:25:03.592: E/dalvikvm(3602): threadid=8: calling run(),name=FinalizerWatchdogDaemon 07-12 08:25:03.642: D/ActivityThread(3602): setTargetHeapUtilization:0.25 07-12 08:25:03.642: D/ActivityThread(3602): setTargetHeapIdealFree:8388608 07-12 08:25:03.642: D/ActivityThread(3602): setTargetHeapConcurrentStart:2097152 07-12 08:25:03.662: I/System.out(3602): Sending WAIT chunk 07-12 08:25:03.662: W/ActivityThread(3602): Application com.himi.clock is waiting for the debugger on port 8100... 07-12 08:25:05.253: I/System.out(3602): Debugger has connected 07-12 08:25:05.253: I/System.out(3602): waiting for debugger to settle... 07-12 08:25:05.454: I/System.out(3602): waiting for debugger to settle... 07-12 08:25:05.654: I/System.out(3602): waiting for debugger to settle... 07-12 08:25:05.854: I/System.out(3602): waiting for debugger to settle... 07-12 08:25:06.054: I/System.out(3602): waiting for debugger to settle... 07-12 08:25:06.254: I/System.out(3602): waiting for debugger to settle... 07-12 08:25:06.455: I/System.out(3602): waiting for debugger to settle... 07-12 08:25:06.655: I/System.out(3602): waiting for debugger to settle... 07-12 08:25:06.855: I/System.out(3602): waiting for debugger to settle... 07-12 08:25:07.055: I/System.out(3602): waiting for debugger to settle... 07-12 08:25:07.256: I/System.out(3602): debugger has settled (1411) 07-12 08:26:55.171: D/ActivityThread(4159): setTargetHeapUtilization:0.25 07-12 08:26:55.171: D/ActivityThread(4159): setTargetHeapIdealFree:8388608 07-12 08:26:55.171: D/ActivityThread(4159): setTargetHeapConcurrentStart:2097152 07-12 08:26:55.391: W/dalvikvm(4159): threadid=1: thread exiting with uncaught exception (group=0x416cd498) 07-12 08:26:55.391: E/AndroidRuntime(4159): FATAL EXCEPTION: main 07-12 08:26:55.391: E/AndroidRuntime(4159): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.himi.clock/com.himi.clock.MainActivity}: android.content.ActivityNotFoundException: Unable to find explicit activity class {com.himi.clock/com.himi.clock.ClockActivity}; have you declared this activity in your AndroidManifest.xml? 07-12 08:26:55.391: E/AndroidRuntime(4159): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2092) 07-12 08:26:55.391: E/AndroidRuntime(4159): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2117) 07-12 08:26:55.391: E/AndroidRuntime(4159): at android.app.ActivityThread.access$600(ActivityThread.java:140) 07-12 08:26:55.391: E/AndroidRuntime(4159): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1213) 07-12 08:26:55.391: E/AndroidRuntime(4159): at android.os.Handler.dispatchMessage(Handler.java:99) 07-12 08:26:55.391: E/AndroidRuntime(4159): at android.os.Looper.loop(Looper.java:137) 07-12 08:26:55.391: E/AndroidRuntime(4159): at android.app.ActivityThread.main(ActivityThread.java:4914) 07-12 08:26:55.391: E/AndroidRuntime(4159): at java.lang.reflect.Method.invokeNative(Native Method) 07-12 08:26:55.391: E/AndroidRuntime(4159): at java.lang.reflect.Method.invoke(Method.java:511) 07-12 08:26:55.391: E/AndroidRuntime(4159): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:808) 07-12 08:26:55.391: E/AndroidRuntime(4159): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:575) 07-12 08:26:55.391: E/AndroidRuntime(4159): at dalvik.system.NativeStart.main(Native Method) 07-12 08:26:55.391: E/AndroidRuntime(4159): Caused by: android.content.ActivityNotFoundException: Unable to find explicit activity class {com.himi.clock/com.himi.clock.ClockActivity}; have you declared this activity in your AndroidManifest.xml? 07-12 08:26:55.391: E/AndroidRuntime(4159): at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1541) 07-12 08:26:55.391: E/AndroidRuntime(4159): at android.app.ActivityThread.resolveActivityInfo(ActivityThread.java:1903) 07-12 08:26:55.391: E/AndroidRuntime(4159): at android.app.LocalActivityManager.startActivity(LocalActivityManager.java:285) 07-12 08:26:55.391: E/AndroidRuntime(4159): at android.widget.TabHost$IntentContentStrategy.getContentView(TabHost.java:694) 07-12 08:26:55.391: E/AndroidRuntime(4159): at android.widget.TabHost.setCurrentTab(TabHost.java:358) 07-12 08:26:55.391: E/AndroidRuntime(4159): at android.widget.TabHost.addTab(TabHost.java:236) 07-12 08:26:55.391: E/AndroidRuntime(4159): at com.himi.clock.MainActivity.addOneTab(MainActivity.java:32) 07-12 08:26:55.391: E/AndroidRuntime(4159): at com.himi.clock.MainActivity.onCreate(MainActivity.java:20) 07-12 08:26:55.391: E/AndroidRuntime(4159): at android.app.Activity.performCreate(Activity.java:5086) 07-12 08:26:55.391: E/AndroidRuntime(4159): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079) 07-12 08:26:55.391: E/AndroidRuntime(4159): at com.lbe.security.service.core.client.b.x.callActivityOnCreate(Unknown Source) 07-12 08:26:55.391: E/AndroidRuntime(4159): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2056) 07-12 08:26:55.391: E/AndroidRuntime(4159): ... 11 more 07-12 08:34:04.128: D/ActivityThread(6074): setTargetHeapUtilization:0.25 07-12 08:34:04.128: D/ActivityThread(6074): setTargetHeapIdealFree:8388608 07-12 08:34:04.128: D/ActivityThread(6074): setTargetHeapConcurrentStart:2097152 07-12 08:34:04.379: W/dalvikvm(6074): threadid=1: thread exiting with uncaught exception (group=0x416cd498) 07-12 08:34:04.389: E/AndroidRuntime(6074): FATAL EXCEPTION: main 07-12 08:34:04.389: E/AndroidRuntime(6074): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.himi.clock/com.himi.clock.MainActivity}: android.content.ActivityNotFoundException: Unable to find explicit activity class {com.himi.clock/com.himi.clock.ClockActivity}; have you declared this activity in your AndroidManifest.xml? 07-12 08:34:04.389: E/AndroidRuntime(6074): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2092) 07-12 08:34:04.389: E/AndroidRuntime(6074): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2117) 07-12 08:34:04.389: E/AndroidRuntime(6074): at android.app.ActivityThread.access$600(ActivityThread.java:140) 07-12 08:34:04.389: E/AndroidRuntime(6074): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1213) 07-12 08:34:04.389: E/AndroidRuntime(6074): at android.os.Handler.dispatchMessage(Handler.java:99) 07-12 08:34:04.389: E/AndroidRuntime(6074): at android.os.Looper.loop(Looper.java:137) 07-12 08:34:04.389: E/AndroidRuntime(6074): at android.app.ActivityThread.main(ActivityThread.java:4914) 07-12 08:34:04.389: E/AndroidRuntime(6074): at java.lang.reflect.Method.invokeNative(Native Method) 07-12 08:34:04.389: E/AndroidRuntime(6074): at java.lang.reflect.Method.invoke(Method.java:511) 07-12 08:34:04.389: E/AndroidRuntime(6074): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:808) 07-12 08:34:04.389: E/AndroidRuntime(6074): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:575) 07-12 08:34:04.389: E/AndroidRuntime(6074): at dalvik.system.NativeStart.main(Native Method) 07-12 08:34:04.389: E/AndroidRuntime(6074): Caused by: android.content.ActivityNotFoundException: Unable to find explicit activity class {com.himi.clock/com.himi.clock.ClockActivity}; have you declared this activity in your AndroidManifest.xml? 07-12 08:34:04.389: E/AndroidRuntime(6074): at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1541) 07-12 08:34:04.389: E/AndroidRuntime(6074): at android.app.ActivityThread.resolveActivityInfo(ActivityThread.java:1903) 07-12 08:34:04.389: E/AndroidRuntime(6074): at android.app.LocalActivityManager.startActivity(LocalActivityManager.java:285) 07-12 08:34:04.389: E/AndroidRuntime(6074): at android.widget.TabHost$IntentContentStrategy.getContentView(TabHost.java:694) 07-12 08:34:04.389: E/AndroidRuntime(6074): at android.widget.TabHost.setCurrentTab(TabHost.java:358) 07-12 08:34:04.389: E/AndroidRuntime(6074): at android.widget.TabHost.addTab(TabHost.java:236) 07-12 08:34:04.389: E/AndroidRuntime(6074): at com.himi.clock.MainActivity.addOneTab(MainActivity.java:32) 07-12 08:34:04.389: E/AndroidRuntime(6074): at com.himi.clock.MainActivity.onCreate(MainActivity.java:20) 07-12 08:34:04.389: E/AndroidRuntime(6074): at android.app.Activity.performCreate(Activity.java:5086) 07-12 08:34:04.389: E/AndroidRuntime(6074): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079) 07-12 08:34:04.389: E/AndroidRuntime(6074): at com.lbe.security.service.core.client.b.x.callActivityOnCreate(Unknown Source) 07-12 08:34:04.389: E/AndroidRuntime(6074): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2056) 07-12 08:34:04.389: E/AndroidRuntime(6074): ... 11 more

仔細閱讀紅色字體處的報錯信息知道：原來是我編寫的APP中含有的多個Activity，必須要在AndroidManifest.xml中進行聲明，聲明如下：

<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android"package="com.himi.clock"android:versionCode="1"android:versionName="1.0" ><uses-sdkandroid:minSdkVersion="15"android:targetSdkVersion="17" /><applicationandroid:allowBackup="true"android:icon="@drawable/ic_launcher"android:label="@string/app_name"android:theme="@style/AppTheme" ><activityandroid:name=".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><activity android:name=".ClockActivity" /><activity android:name=".StopwatchActivity" /><activity android:name=".TimerActivity" /></application></manifest>

再次加載程序到手機里面，發現這時候是可以運行的，沒有報錯了

?

那么為什么要這樣在AndroidManifest.xml聲明注冊多個activity？？？

答：我們知道不同activity代表不同的窗口界面，Android系統只有先注冊了不同的activity，系統內部才能對它操作，比如利用intent操作。

轉載于:https://www.cnblogs.com/hebao0514/p/4640494.html

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