Question

Whenever I want to use any resource element in the non-root package, I have to import my own R class (not Android R class). For example,

Root package com.example.test and a file Main.java

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
}

No need to import R class.

When I create another package, com.example.test.something and a new class in there Something.java, I have to import my own R.class

import com.example.test.R;

//...other code...

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
}

This happens automatically when I move a Java file from root to non-root package.

Why is this so important?

Answer 1

Your R class lives in your application package com.example.test — check out it’s package declaration. If you want to reference it from any other package, you need to import it or fully qualify its name, like any other class.