您好我想更改默认活动.但是,当我这样做时,应用程序根本没有启动而没有任何错误

<activity 
        android:name="com.example.dimmer.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="com.example.dimmer.DevicesActivity" >
    </activity>

这样MainActivty就可以毫无问题地启动.当我按下按钮时,它也会转到设备活动.所以一切正常.
现在我需要DevcieACtivty作为默认值.

我改变了Manifest

<activity 
            android:name="com.example.dimmer.DevicesActivity"
            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="com.example.dimmer.MainActivity" >
        </activity>

但现在应用程序无法启动.没有错误.没有在控制台中写入.
它只是没有做任何事情,
可能有什么问题？

它开始写下面的错误
ActivityManager：开始：Intent {act = android.intent.action.MAIN cat = [android.intent.category.LAUNCHER] cmp = com.example.dimmer / .MainActivity}
[2014-05-16 21:17:10 – Dimmer] ActivityManager：java.lang.SecurityException：Permission Denial：start Intent {act = android.intent.action.MAIN cat = [android.intent.category.LAUNCHER] flg =来自null的0x10000000 cmp = com.example.dimmer / .MainActivity}(pid = 13093,uid = 2000)需要null

完整的清单

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.dimmer"
    android:versionCode="1"
    android:versionName="1.0" 
    android:hardwareAccelerated="false">

    <uses-sdk
        android:minSdkVersion="9"
        android:targetSdkVersion="14" />
    <uses-permission android:name="android.permission.INTERNET" /> 

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >

        <activity 
            android:name="com.example.dimmer.DevicesActivity"
            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="com.example.dimmer.MainActivity" >
        </activity>

    </application>

</manifest>


[2014-05-16 22:13:25 - Dimmer] Android Launch!
[2014-05-16 22:13:25 - Dimmer] adb is running normally.
[2014-05-16 22:13:25 - Dimmer] Performing com.example.dimmer.MainActivity activity launch
[2014-05-16 22:13:26 - Dimmer] Uploading Dimmer.apk onto device 'SH17VT514235'
[2014-05-16 22:13:26 - Dimmer] Installing Dimmer.apk...
[2014-05-16 22:13:29 - Dimmer] Success!
[2014-05-16 22:13:29 - Dimmer] Starting activity com.example.dimmer.MainActivity on device SH17VT514235
[2014-05-16 22:13:29 - Dimmer] ActivityManager: Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] cmp=com.example.dimmer/.MainActivity }
[2014-05-16 22:13:29 - Dimmer] ActivityManager: java.lang.SecurityException: Permission Denial: starting Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 cmp=com.example.dimmer/.MainActivity } from null (pid=15458, uid=2000) requires null

解决方法:

由于您已将包定义为“com.example.dimmer”,因此可以删除包名称并仅使用活动with dot in front的名称：

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >

    <activity 
        android:name=".DevicesActivity"
        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=".MainActivity" >
    </activity>

</application>

此外,请检查Eclipse中的运行配置设置.如果您的启动活动设置为MainActivity,并且在清单中将DevicesActivity设置为main,则在通过Eclipse启动时,您的应用可能无法启动.单击箭头图标,然后选择“运行配置”,

然后确保选择DevicesActivity作为Launch：