Too many Activities being started when launching an Android Application

Question

Hi guys.

I am confirming about creating activity.

My Manifest.xml is like this :

<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".FirstActivity"
          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=".SecondActivity"
          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=".ThirdActivity"
          android:label="@string/app_name">
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>

You can see property action android:name= property is "android.intent.action.MAIN" and category android:name= is "android.intent.category.LAUNCHER" for all activities.

When application starts up, it calls FirstActivity.

Then calls useless Activity such as ThirdActivity or SecondActivity.

In this case, is my manifest.xml correct?

Or, do I need to set another property to Second and Third activity? If so, what is that?

I wonder manifest.xml file is right for my case.

Please advise.

Thanks in advance.

Answer 1

Try this config:

<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".FirstActivity" 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=".SecondActivity" android:label="@string/app_name">
    <intent-filter>
    </intent-filter>
</activity>
 <activity android:name=".ThirdActivity" android:label="@string/app_name">
    <intent-filter>
    </intent-filter>
</activity>

Answer 2

Think of an Intent as message used to start an Activity to do something. So I can create an Intent to view a web page and an application with an Activity which knows how to view a web page - most likely the browser - can intercept his Intent as act on it.

You tell Android which Activities can act on which Intents using the <intent-filter> part of your Manifest.

The MAIN Intent is a special one. This is sent to an application when it is launched and basically it says "Go!" So the Activity which shoud be displayed first needs to intercept this by having a correctly defined <intent-filter>.

As you had all three Activities with MAIN in their filter they all responded to the request to start your application. So you should have that <intent-filter> only for FirstActivity.

Answer 3

One of the other problems with using <category android:name="android.intent.category.LAUNCHER" /> for more than one activity is that the Phone's launcher menu will display more than one icon...

From the docs:

CATEGORY_LAUNCHER The activity can be the initial activity of a task and is listed in the top-level application launcher.