setLayoutParams不生效，请大家指点

protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
	}

	@Override
	public boolean onTouchEvent( MotionEvent event) {
		RelativeLayout layout  = (RelativeLayout) this.getLayoutInflater().inflate(R.layout.activity_main, null);
		LinearLayout menu_layout = (LinearLayout)layout.findViewById(R.id.menu);
	        mp  =  (MarginLayoutParams)menu_layout.getLayoutParams();  
		mp.leftMargin=200;
		mp.topMargin=200;
	        menu_layout.setLayoutParams(mp);
		return true;
	}

布局文件：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    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"
 	android:orientation="horizontal"
    tools:context=".MainActivity" >
	<LinearLayout
	      	android:layout_width="fill_parent"
   		  	android:layout_height="fill_parent"
   		 	android:background="#f00" 
   			android:id="@+id/menu">
	    
	    <TextView
	        android:id="@+id/text"
	        android:layout_width="wrap_content"
	        android:layout_height="wrap_content"
	        android:text="@string/hello_world" />
	</LinearLayout>    

    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="hello" />
    
</RelativeLayout>