Difference between getContext getApplicationContext getBaseContext and this

Question

What is the difference between getContext     getApplicationContext     getBaseContext     and  this     Though this is simple question I am unable to understand the basic difference between them  Please give some easy examples if possible

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getApplicationContext   - Returns the context for all activities running in application  getBaseContext   -  If you want to access Context from another context within application you can access  getContext   - Returns the context view only current running activity

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getApplicationContext        this is used for application level and refer to all activities    getContext   and getBaseContext        is most probably same  these are reffered only current activity which is live    this     is  refer current class object always

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The question  quot what the Context is quot  is one of the most difficult questions in the Android universe  Context defines methods that access system resources  retrieve application s static assets  check permissions  perform UI manipulations and many more  In essence  Context is an example of God Object anti-pattern in production  When it comes to which kind of Context should we use  it becomes very complicated because except for being God Object  the hierarchy tree of Context subclasses violates Liskov Substitution Principle brutally  This blog post  now from Wayback Machine  attempts to summarize Context classes applicability in different situations  Let me copy the main table from that post for completeness    ---------------------------- ------------- ---------- --------- ----------------- -------------------                                 Application   Activity   Service   ContentProvider   BroadcastReceiver    ---------------------------- ------------- ---------- --------- ----------------- -------------------    Show a Dialog                NO            YES        NO        NO                NO                    Start an Activity            NO             YES        NO         NO                 NO                     Layout Inflation             NO             YES        NO         NO                 NO                     Start a Service              YES           YES        YES       YES               YES                   Bind to a Service            YES           YES        YES       YES               NO                    Send a Broadcast             YES           YES        YES       YES               YES                   Register BroadcastReceiver   YES           YES        YES       YES               NO                     Load Resource Values         YES           YES        YES       YES               YES                  ---------------------------- ------------- ---------- --------- ----------------- -------------------    An application CAN start an Activity from here  but it requires that a new task be created   This may fit specific use cases  but can create non-standard back stack behaviors in your application and is generally not recommended or considered good practice  This is legal  but inflation will be done with the default theme for the system on which you are running  not what   s defined in your application  Allowed if the receiver is null  which is used for obtaining the current value of a sticky broadcast  on Android 4 2 and above

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View getContext     Returns the context the view is currently running in   Usually the currently active Activity  Activity getApplicationContext     Returns the context for the entire application  the process all the Activities are running inside of    Use this instead of the current Activity context if you need a context tied to the lifecycle of the entire application  not just the current Activity  ContextWrapper getBaseContext     If you need access to a Context from within another context  you use a ContextWrapper   The Context referred to from inside that ContextWrapper is accessed via getBaseContext

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Most answers already cover getContext   and getApplicationContext   but getBaseContext   is rarely explained   The method getBaseContext   is only relevant when you have a ContextWrapper  Android provides a ContextWrapper class that is created around an existing Context using   ContextWrapper wrapper   new ContextWrapper context     The benefit of using a ContextWrapper is that it lets you    modify behavior without changing the original Context     For example  if you have an activity called myActivity then can create a View with a different theme than myActivity   ContextWrapper customTheme   new ContextWrapper myActivity       Override   public Resources Theme getTheme          return someTheme        View myView   new MyView customTheme     ContextWrapper is really powerful because it lets you override most functions provided by Context including code to access resources  e g  openFileInput    getString     interact with other components  e g  sendBroadcast    registerReceiver     requests permissions  e g  checkCallingOrSelfPermission    and resolving file system locations  e g  getFilesDir     ContextWrapper is really useful to work around device version specific problems or to apply one-off customizations to components such as Views that require a context   The method getBaseContext   can be used to access the    base    Context that the ContextWrapper wraps around  You might need to access the    base    context if you need to  for example  check whether it   s a Service  Activity or Application   public class CustomToast     public void makeText Context context  int resId  int duration        while  context instanceof ContextWrapper          context   context baseContext              if  context instanceof Service           throw new RuntimeException  Cannot call this from a service                          Or if you need to call the    unwrapped    version of a method   class MyCustomWrapper extends ContextWrapper      Override   public Drawable getWallpaper         if  BuildInfo DEBUG          return mDebugBackground        else         return getBaseContext   getWallpaper

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Context provides information about the Actvity or Application to newly created components   Relevant Context should be provided to newly created components  whether application context or activity context   Since Activity is a subclass of Context  one can use this to get that activity s context

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From this docs  I understood that you should use      Try using the context-application instead of a context-activity

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A Context is    an abstract class whose implementation is provided by the Android system  It allows access to application-specific resources and classes  as well as up-calls for application-level operations such as launching activities  broadcasting and receiving intents  etc

[android] Difference between getContext() , getApplicationContext() , getBaseContext() and "this"

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