Get Width and Height of view with match_parent constant

I have declared Linear Layout in my main_layout.xml, which has layout_with with value of match_parent and I am trying to get the width of Linear Layout programmatically in pixles, but i am getting width 0. Here is my main_layout.xml.

<RelativeLayout xmlns:android="http://ift.tt/nIICcg"
    xmlns:tools="http://ift.tt/LrGmb4"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.bairnlogixgame.MainActivity" > 

    <LinearLayout
        android:id="@+id/llTextvieConainter"
        android:layout_width="match_parent"
        android:layout_height="150dp"
        android:background="@drawable/view_borders"
        android:orientation="vertical" 
        />

</RelativeLayout>

Here is my MainActivity code.

public class MainActivity extends ActionBarActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mMainContainer = (LinearLayout) findViewById(R.id.llTextvieConainter);

        int mWidth = getBoxDimensions(mMainContainer)[0];
        Log.i(TypeRacingConstants.LOGCAT,
                "Width of box :" + mWidth); 

    }

    private int[] getBoxDimensions(LinearLayout linearLayout) {
        int boxDiamensions[] = { 0, 0 };
        linearLayout.measure(MeasureSpec.EXACTLY, MeasureSpec.EXACTLY);
        boxDiamensions[0] = linearLayout.getMeasuredWidth();
        boxDiamensions[1] = linearLayout.getMeasuredHeight();
        return boxDiamensions;
    }   
}

Please help me, where i am getting wrong.