Android DP toughts? - android-layout

Question

Can someone please give me directions on this:
I've got a ListView, the adapter got a LinearLayout and in this I got four more LinearLayouts.
Now I read about dp and it is relative to 160, but when I read different examples this number "160" seems to be different on different screens, so how do I work with dp?
I am used to work with % in this cases.
Now I want my four LinearLayouts to be:
55dp
35pd
35pd
35pd
Like if the dp was 160!
But as I mentioned above, this dosen't work on all screens.
Can someone tell me how I should work with this? Directions or a good tutorial or similar?
This is what I have tried, and come up with so far:
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_marginTop="15dip"
android:layout_marginBottom="15dip"
android:paddingTop="15dip"
android:paddingBottom="15dip" >
<LinearLayout
android:orientation="vertical"
android:layout_width="55dp"
android:layout_height="wrap_content"
android:gravity="center">
<TextView
android:id="#+id/text1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="top" />
</LinearLayout>
<LinearLayout
android:orientation="vertical"
android:layout_width="35dp"
android:layout_height="wrap_content"
android:gravity="center">
<Button
android:text="Woho"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
<TextView
android:text="Woho"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
<Button
android:text="Woho"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
</LinearLayout>
<LinearLayout
android:orientation="vertical"
android:layout_width="35dp"
android:layout_height="wrap_content"
android:gravity="center">
<Button
android:text="Woho"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
<TextView
android:text="Woho"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
<Button
android:text="Woho"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
</LinearLayout>
</LinearLayout>

Answer 1

As per the android documentation, 1 DP = 1 pixel on a 160 DPI screen. If the screen is 240 DPI, then 1.5pixel = 1 DP. the size of one DP is independent of underlying hardware resolution but a function of DPI of the screen.
To your layout question, if you assign a fixed width value to your layout, then it will not look good on larger screen sizes.
Better to use layoutweight to distribute the width between those layouts.