android:layout_height="0.5dp" will be error -

i want user imageview

<imageview     android:layout_width="match_parent"     android:layout_height="0.4dp"     android:background="@color/bottomline" /> 

but android:layout_height="0.4dp" error !

the error:suspicious size: make view invisible, should used layout_weight.

and found error appear if imageview first view in linearlayout,like this

<linearlayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@color/backgroundcolor" android:orientation="vertical" >  <!-- first view error -->  <imageview     android:layout_width="match_parent"     android:layout_height="0.4dp"     android:layout_margintop="10dp"     android:background="@color/bottomline" />  <!-- second view  right -->  <imageview     android:layout_width="match_parent"     android:layout_height="0.4dp"     android:layout_margintop="10dp"     android:background="@color/bottomline" />  <textview     android:layout_width="match_parent"     android:layout_height="wrap_content"     android:background="@color/white"     android:padding="10dp"     android:text="李文"     android:textcolor="@color/black_text_color"     android:textsize="16sp" /> 

how solve problem ?

you should try give height in px if want thin line.