如何启动应用程序上下文的Intent

Question

I found almost the same question: How to start an Intent if context is not Activity Context but Application Context

but I faild to do it when using https://stackoverflow.com/a/9238105/6593395

public void onReceive(Context context, Intent intent) {
    String action = intent.getAction();
    if ("android.intent.action.BOOT_COMPLETED".equals(action)) {
        Intent applicationIntent = new Intent(context, myCamApplication.class);
        applicationIntent.setAction(myCamApplication.class.getName());
        applicationIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        context.startActivity(applicationIntent);

the error log:

Caused by: android.content.ActivityNotFoundException: Unable to find explicit activity class {com.fenchtose.asyncamera/com.eason.mycamera.myCamApplication}; have you declared this activity in your AndroidManifest.xml?

I have registered this myCamApplication class as my application class inside AndroidManifest.xml

    <application
    android:name=".myCamApplication"
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme"
    >
    <receiver
        android:name=".BootComplete"
        android:enabled="true"
        android:exported="true">
        <intent-filter>
            <action android:name="android.intent.action.BOOT_COMPLETED" />
        </intent-filter>
    </receiver>
    <activity
        android:name=".myCam"
        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>

So, Anyone could help?

Answer 1

You can not start an Application class. You can only start an Activity.

Change your code from eg:

Intent applicationIntent = new Intent(context, myCamApplication.class);

to

Intent applicationIntent = new Intent(context, myCam.class);

Answer 2

尝试创建另一个Activity并将其添加到您的Manifest.xml ，看看是否有任何错误，不要忘记添加此代码<activity android:name=".yourSecondActivity" />并启动一个新的Intent

Answer 3

The problem here is that you don't understand basic principles. In android you have only 4 components: Activity, Service, ContentProvider, BroadcastReceiver. So in your manifest you declare that you have Application (name, attributes...) and inside the application you have Activities, Services, Receivers, ContentProviders.

Your application is not your Application class. So to start your application you should start default activity:

Intent intent = new Intent(context, MainActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);//because we use Application context
startActivity(intent);

PS Your Application class will start automatically. Lifecycle of application is following: Start of Application class -> Start of Component(service, activity..) -> Stop of Component(service...) -> Stop of Application class

PSS There is no need to check the action in onReceive - it will be there for the only reason:

<intent-filter>
    <action android:name="android.intent.action.BOOT_COMPLETED" />
</intent-filter>