Reference to elements of fragment from activity
<p>It is possible to get reference to element(like button) defined in xml layout of fragment and use it in another activity?</p>

<p>I tried to do that but have null object reference.</p>

<p>fragment_date_picker.xml</p>

<pre><code>&lt;TimePicker
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/timePicker"
    android:layout_gravity="center_horizontal|top" /&gt;

&lt;Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="ok"
    android:id="@+id/bt_ok"
    android:layout_gravity="center" /&gt;
</code></pre>

<p>MainActivity.java</p>

<pre><code>btPickTime=(Button)findViewById(R.id.bt_pickTime);
    AlarmManager alarmManager=(AlarmManager)getSystemService(ALARM_SERVICE);
    final DatePickerFragment dp=new DatePickerFragment();

    btOk=(Button)findViewById(R.id.bt_ok);
    btOk.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            FragmentManager fm = getFragmentManager();
            FragmentTransaction ft = fm.beginTransaction();
            ft.remove(dp);
            ft.commit();
        }
    });
    btPickTime.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            FragmentManager fm = getFragmentManager();
            FragmentTransaction ft = fm.beginTransaction();
            ft.add(R.id.ll_main
                    ,dp);
            ft.commit();

        }
    });
</code></pre>