For what purpose Context class is used in android?Please explain me in depth and be more specific .I read all other posts but none of them were specific enough to give me clear understanding.
I know Content class 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.
Like Here,
Intent intent=new Intent(this,new_class.class);
why we are passing Main activity context into the Intent constructor call.what type of information does this activity context contain,how will it help it ,what type of resource access is it providing to it ?(with example please).
Similarly,
here,
TextView textview=new TextView(this);
Why TextView need activity context?How does it help it.
There are already several good explanations of Context on Stackoverflow (see the linked questions and us the "search" feature. Also, the source code for Android is available on grepcode.com and you can look yourself if you are really interested. Why trust someone else's answer if you can look yourself? ;-)
However, I will answer your specific questions:
Intent intent=new Intent(this,new_class.class);
why we are passing Main activity context into the Intent constructor
call.what type of information does this activity context contain,how
will it help it ,what type of resource access is it providing to it
?(with example please).
In this case (the 2-argument constructor for Intent), the Context parameter is only used to determine the package name of the target Activity. Assuming that the package name of your application is "com.example.app", and MyActivity is an `Activity of your application, the following code snippets are all functionally identical:
Intent intent = new Intent(this, MyActivity.class);
Intent intent = new Intent(getApplicationContext(), MyActivity.class);
Intent intent = new Intent();
intent.setComponent(new ComponentName(this, "com.example.app.MyActivity");
Intent intent = new Intent();
intent.setComponent(new ComponentName(this, MyActivity.class);
Intent intent = new Intent();
intent.setComponent(new ComponentName("com.example.app", MyActivity.class);
Intent intent = new Intent();
intent.setClass(this, MyActivity.class);
Intent intent = new Intent();
intent.setClassName("com.example.app", "com.example.app.MyActivity");
Similarly, here,
TextView textview=new TextView(this);
Why TextView need activity context?How does it help it.
All Views need a Context. Think of the Context as the "owner of the View". This controls the lifetime of the View. In general, a View should have the same lifetime as its owning Activity, which is why you usually pass the Activity as the Context parameter when creating a View. When the Activity is destroyed, all of the owned Views are also destroyed. Additionally, the View uses the Context to gain access to resources (drawables, layouts, strings, themes, etc.).
It act as a Interface to global information about an application environment. This 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.
You can get all the information from delveloper's official documentation... https://developer.android.com/reference/android/content/Context.html
