Why do we always type cast in Android/Java?

Question

I am writing an Android app and just was curious about why we must always type-cast in Android. I understand that we need to be sure of the type so that our code runs proper

Answer 1

In android - while writing java code you need to bring XML code inside Java.

So we use R.id.drawer_layout is what we want to bring inside java which becomes findViewById(R.id.drawer_layout) which returns an Object.

So we then assign it to a variable declared at top.

 private DrawerLayout mDrawerLayout;

where DrawerLayout is a class in java android.

mDrawerLayout = findViewById(R.id.drawer_layout);

Since findViewById(R.id.drawer_layout) returns an object and we are assigning it to a variable we need to typecast by using

mDrawerLayout = (DrawerLayout)findViewById(R.id.drawer_layout);