how to use activity context from other activity?

Question

I want to use activity context from another activity simple code example below Any idea ?

public class Activity_A extends AppCompatActivity {

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

---

public class Activity_B extends AppCompatActivity {
Dialog dialog1 ;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_Activity_B);

dialog1 = new Dialog(I want Activity_A Context) ; // Is this possible ??

}
}

---

Thanks