Apps How Does Android know which Java to Execute First ???

[ac4android]

Hi. I am working thru some codes and cannot see the wood for the trees at the moment.

I have several layers of activities, the topmost is called "TopLevelActivity", then followed by several activities and some pure Java codes.

How does Android know which code to execute first? There's no "public static void main(String[] arghs)" in any of the activity- Java to kick off the sequence of activities.

 

[Deleted User]

There's no main method because your app, along with all the others runs in a kind of container, managed by the Android runtime environment. All apps have a lifecycle, with specifically defined methods being called at various points e.g. to suspend or restart the app.
As for your main activity, that's all configured using the manifest XML file

<application
       android:icon="@drawable/ic_launcher"
       android:label="@string/app_name"
       android:theme="@style/AppTheme" >
      
       <activity
          android:name=".MainActivity"
          android:label="@string/title_activity_main" >
      
          <intent-filter>
             <action android:name="android.intent.action.MAIN" />
             <category android:name="android.intent.category.LAUNCHER"/>
          </intent-filter>
      
       </activity>
      
   </application>

 

[scary alien]

^^^ +10, @LV426!

A couple other lifecycle resources and references for you, @ac4android:

http://developer.android.com/training/basics/activity-lifecycle/index.html

http://www.vogella.com/tutorials/AndroidLifeCycle/article.html

 

[Deleted User]

Nice one Alien

 

[ac4android]

There's no main method because your app, along with all the others runs in a kind of container, managed by the Android runtime environment. All apps have a lifecycle, with specifically defined methods being called at various points e.g. to suspend or restart the app.
As for your main activity, that's all configured using the manifest XML file

<application
       android:icon="@drawable/ic_launcher"
       android:label="@string/app_name"
       android:theme="@style/AppTheme" >
     
       <activity
          android:name=".MainActivity"
          android:label="@string/title_activity_main" >
     
          <intent-filter>
             <action android:name="android.intent.action.MAIN" />
             <category android:name="android.intent.category.LAUNCHER"/>
          </intent-filter>
     
       </activity>
     
   </application>

Thx.