What are intent-filters in Android

Question

In my android app  I wanted to start an activity  B  from initial activity  A   I have created classes for both of these  However when using following code to start B  I get a runtime error  application has stopped unexpectedly  try again  Here is my code   Intent myIntent   new Intent this  AddNewActivity class   startActivity myIntent      When I added a new entry in AndroidManifest xml manifest application activity intent-filers for activity B then the application worked   I have two questions    When there are multiple activities entries in AndroidManifest xml  how does android know which activity to start first  I could not understand intent-filters  Can anyone please explain    Here is my partial AndroidManifest xml   lt application android icon   drawable icon  android label   string app name  gt       lt activity android name   ListAllActivity                android label   string app name  gt           lt intent-filter gt               lt action android name  android intent action MAIN    gt               lt category android name  android intent category LAUNCHER    gt           lt  intent-filter gt       lt  activity gt       lt activity android name   AddNewActivity  android label   string app name  gt           lt intent-filter gt               lt action android name  android intent action MAIN    gt               lt category android name  android intent category LAUNCHER    gt           lt  intent-filter gt       lt  activity gt   lt  application gt

User · Answer

The Activity which you want it to be the very first screen if your app is opened  then mention it as LAUNCHER in the intent category and remaining activities mention Default in intent category   For example  -  There is 2 activity A and B    The activity A is LAUNCHER so make it as LAUNCHER in the intent Category and B is child for Activity A so make it as DEFAULT    lt application android icon   drawable icon  android label   string app name  gt       lt activity android name   ListAllActivity                android label   string app name  gt           lt intent-filter gt               lt action android name  android intent action MAIN    gt               lt category android name  android intent category LAUNCHER    gt           lt  intent-filter gt       lt  activity gt       lt activity android name   AddNewActivity  android label   string app name  gt           lt intent-filter gt               lt action android name  android intent action MAIN    gt               lt category android name  android intent category DEFAULT    gt           lt  intent-filter gt       lt  activity gt   lt  application gt

User · Answer

An intent filter is an expression in an app s manifest file that specifies the type of intents that the component would like to receive   When you create an implicit intent  the Android system finds the appropriate component to start by comparing the contents of the intent to the intent filters declared in the manifest file of other apps on the device  If the intent matches an intent filter  the system starts that component and delivers it the Intent object   AndroidManifest xml   lt activity android name   HelloWorld      android label   string app name  gt       lt intent-filter gt           lt action android name  android intent action VIEW   gt           lt category android name  android intent category DEFAULT   gt           lt category android name  android intent category BROWSABLE   gt           lt data android scheme  http  android host  androidium org   gt       lt  intent-filter gt   lt  activity gt    Launch HelloWorld  Intent intent   new Intent  Intent ACTION VIEW  Uri parse  http   androidium org     startActivity intent

User · Answer

When there are multiple activities   entries in AndroidManifest xml  how   does android know which activity to   start first    There is no  first   In your case  with your manifest as shown  you will have two icons in your launcher  Whichever one the user taps on is the one that gets launched      I could not understand intent-filters    Can anyone please explain    There is quite a bit of documentation on the subject  Please consider reading that  then asking more specific questions   Also  when you get  application has stopped unexpectedly  try again   use adb logcat  DDMS  or the DDMS perspective in Eclipse to examine the Java stack trace associated with the error

User · Answer

intent filter is expression which present in manifest in your app that specify the type of intents that the component is to receive  If component does not have any intent filter it can receive explicit intent  If component with filter then receive both implicit and explicit intent

User · Answer

When you create an implicit intent  the Android system finds the appropriate component to start by comparing the contents of the intent to the intent filters declared in the manifest file of other apps on the device  If the intent matches an intent filter  the system starts that component and delivers it the Intent object  If multiple intent filters are compatible  the system displays a dialog so the user can pick which app to use   An intent filter is an expression in an app s manifest file that specifies the type of intents that the component would like to receive  For instance  by declaring an intent filter for an activity  you make it possible for other apps to directly start your activity with a certain kind of intent  Likewise  if you do not declare any intent filters for an activity  then it can be started only with an explicit intent   According  Intents and Intent Filters

User · Answer

First change the xml  mark your second activity as DEFAULT   lt activity android name   AddNewActivity  android label   string app name  gt           lt intent-filter gt               lt action android name  android intent action MAIN    gt               lt category android name  android intent category DEFAULT    gt           lt  intent-filter gt       lt  activity gt    Now you can initiate this activity using StartActivity method

User · Answer

There can be no two Lancher AFAIK  Logcat is a usefull tool to debug and check application machine status in the behind  it will be automatic while switching from one activity to another activity

User · Answer

Keep the first intent filter with keys MAIN and LAUNCHER and add another as ANY NAME and DEFAULT   Your LAUNCHER will be activity A and DEFAULT will be your activity B

User · Answer

When there are multiple activities set as main and launcher with an intent filter in the manifest  Then first activity considers as Launcher activity  and android launch or open the first activity    lt category android name  android intent category LAUNCHER    gt      The above code makes an app icon available in the device menu  so if we declare 2 launcher activity in the manifest  there will be 2 app icons get created in the device app menu   So there will be 2 app icons  on click of the first icon  first declared activity in manifest will be launch  and click of another second declared activity gets launch

User · Answer

If possible try this one instant solution   Intent intent  new Intent getApplicationBaseContext second Act class   StartActivity intent

[android] What are intent-filters in Android?

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