Question

I want to have a relative layout inside another full-screen relative layout, occupying full width but 50% of its parent’s height, preferably done with XML and not java code.

I have figured out how how to align parent’s center, and how to fill up the width, but is there a way to get 50% of parent’s height? What about 30%? 6.2834%?

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent" android:layout_height="fill_parent">

    <RelativeLayout
        android:layout_width="fill_parent"
        android:layout_height="??????????"
        android:layout_centerInParent="true" >

The reason I’m trying to do percentage is that, if I specify it with “dip”, while the object will remain the same size, the layout will look a lot different on different screen sizes (e.g. a phone and a tablet).

EDIT:

Thank you for all the answers about using LinearLayout and weighting. I have looked at that before, too. I feel I might have over-simplified the problem. Say I need something like this:

I suppose I could use complicated LinearLayout and weighting to outline the center square, then having the center square to fill_parent, like so:

But then what should I do with the other 3 squares (layouts)? Can I have another “layer” of LinearLayout for another square? Or should I divide up the whole screen into many, many small cells and having these sublayouts span over multiple cells (not sure if this is even possible)?

Answer 1

I usually go with a LinearLayout for this and set the weight to a certain percentage :

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent"
    android:orientation="vertical">

    <View
        android:layout_width="fill_parent"
        android:layout_height="0dp"
        android:layout_weight="25"/>

    <RelativeLayout
        android:layout_width="fill_parent"
        android:layout_height="0dp"
        android:layout_weight="50">
     </RelativeLayout>

     <View
         android:layout_width="fill_parent"
         android:layout_height="0dp"
         android:layout_weight="25"/>

</LinearLayout>

To your edit:

At some point you need to determine the layout. Start by taking the layout in groups. Look for patterns. In your simple explanation we have devised a way using a linearlayout to group 3 objects with one in the middle. With your new layout, could you group those items in any way?

Once you have simple layout patterns set, maybe add specific spacing that you are looking for by defining weights. Then you might want to add a relative layout and start anchoring views to specific views. Ask yourself do they overlap? Does one view always position on top of other views or on the sides. What defines the bounds of your views and then take it from there using linear layouts, weights, relative layouts, toLeftOf, toRightOf, bellow, above, margins, and padding.

Here is an example of what I mean by grouping like objects. It’s by no means the best solutions but that all depends on how you define the positioning parameters.

Yellow = vertical linear layout

Green = horizontal linear layouts

You have 1 large vertical layout and inside two horizontal layouts with multiple objects inside of that. From there you can break it down into easier to manage portions on how to arrange and item within that layout. Now with relative layouts you could position items relative to another object, you could remove some of the work handled by the linear layouts but you will then be defining their distance relative to the other objects and might have to fiddle to get the layout to adjust properly on different screen sizes (reason to not use static positioning).