Develop Reference

How to place 2 views to the bottom of the parent but one stacked above the other?

In a RelativeLayout if a view has android:layout_alignParentBottom="true” then it is placed to the bottom of the parent.
If 2 views have android:layout_alignParentBottom="true” then both are placed on the bottom, but 1 above the other.
How can I have 2 view to have the setting android:layout_alignParentBottom="true” and one to be stacked over the other?
android:layout_above seems to be not applicable/working for this case.

Put the views inside a LinearLayout with orientation - vertical, and put
layout_alignParentBottom=true
To the LinearLayout;
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:background="#color/black"
android:layout_height="match_parent">
<LinearLayout
android:layout_alignParentBottom="true"
android:background="#color/red"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
</RelativeLayout>

layout_above means "above" in a Y direction, not in a Z direction, if that makes sense. If you want them to overlay, remove the layout_above attribute and make them both layout_alignParentBottom=true.

They won't be placed one after another if you have set only android:layout_alignParentBottom="true”. Please paste your layout xml so that the real issue can be found.

How to Prevent Scrolling within FrameLayouts and Instead Have the Parent LinearLayout Handle all Scrolling?

I have a scrollable LinearLayout parent with a few FrameLayouts nested inside it as follows:
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fillViewport="true"
android:scrollbars="vertical"
android:orientation="vertical">
<FrameLayout
android:id="#+id/hb_container"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
<FrameLayout
android:id="#+id/gn_container"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
<FrameLayout
android:id="#+id/yt_container"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
</LinearLayout>
I would like FrameLayouts to take up the space they need, allowing for scrolling of the full view through the LinearLayout.
Issue is: the LinearLayout will only take up the screen, it won't scroll, instead the FrameLayout's will scroll if the content overflows the bottom of the screen.
To be clear, I just want the FrameLayouts to fill whatever space they need, and the LinearLayout can scroll it like one long view. Must I fix the FrameLayout heights to achieve this? If so, is there risk of my layout breaking on different screen sizes/densities (or does DP really work in all cases?).
Thank you immensely!
EDIT: I have confirmed that setting fixed heights in the FrameLayout does exactly what I want this to do: scroll as one. However, why doesn't wrap_content measure the height and then go from there? That is what I expected the case was... I'm not certain how to judge the right heights for each element.

Try adding a scrollview to the layout
<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fillViewport="true"
android:orientation="vertical">
<FrameLayout
android:id="#+id/hb_container"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
<FrameLayout
android:id="#+id/gn_container"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
<FrameLayout
android:id="#+id/yt_container"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
</LinearLayout>
</ScrollView>

Putting two child layout inside a parent layout with equal weight distribution in Android

I want to use two child layout (one linear layout and one relative layout) inside a parent layout (relative layout) in such a way that both of the child layout will take exactly half of the screen and items inside of each child layout will not cause one child layout to get more width than another one!

It is pretty easy, use parameter layout_weight in children of LinearLayout, something like this:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent">
<RelativeLayout
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="match_parent">
</RelativeLayout>
<RelativeLayout
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="match_parent">
</RelativeLayout>
</LinearLayout>

If I understand correctly from your illustration, the red box is a RelativeLayout, whereas the green boxes are a LinearLayout and a RelativeLayout.
A simple solution would be to center an empty View inside the RelativeLayout and align the two child Views against it:
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_toLeftOf="#+id/v_center" />
<View
android:id="#+id/v_center"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_centerInParent="true" />
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_toRightOf="#+id/v_center" />
</RelativeLayout>
A nice little bonus here is that you can provide some spacing between the two by specifying the View's dimensions.
Beware, however, that RelativeLayouts aren't very efficient, and nesting them is an especially bad idea. I suggest using the hierarchy viewer tool to inspect the layout timings to make sure it's relatively fast, and to try to avoid nesting the layouts in this fashion.

How to make several RelativeLayouts each occupying a potion of the screen?

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)?

Try to use LinearLayout with weightSum
<LinearLayout 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:weightSum="2"
android:gravity="center_vertical"
android:orientation="vertical" >
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:background="#FF0000">
</RelativeLayout>
</LinearLayout>

If you don't absolutely need it nested in one RelativeLayout you can use weight in a LinearLayout as others have pointed out. I just added in an additional RelativeLayout above and below so you can use the rest of the screen if you are trying to. If not, just remove the other RelativeLayouts.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/ParentLinearLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:weightSum="10" >
<RelativeLayout
android:id="#+id/RelativeLayoutTop"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="2.5"
android:background="#color/torange" >
</RelativeLayout>
<RelativeLayout
android:id="#+id/RelativeLayoutMid"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="5"
android:background="#color/tpurple"
android:padding="8dp" >
<TextView
android:id="#+id/description"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:text="#string/describe"
android:textAppearance="?android:attr/textAppearanceLarge" />
</RelativeLayout>
<RelativeLayout
android:id="#+id/RelativeLayoutBottom"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="2.5"
android:background="#color/torange" >
</RelativeLayout>

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).

Maybe try using a LinearLayout with 3 layouts inside with android:layout_weight set to 1, 2, 1.
<?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" >
<RelativeLayout
android:background="#FF0000"
android:layout_weight="1"
android:layout_width="match_parent"
android:layout_height="0dip" >
</RelativeLayout>
<RelativeLayout
android:background="#00FF00"
android:layout_weight="2"
android:layout_width="match_parent"
android:layout_height="0dip" >
</RelativeLayout>
<RelativeLayout
android:background="#FF0000"
android:layout_weight="1"
android:layout_width="match_parent"
android:layout_height="0dip" >
</RelativeLayout>
</LinearLayout>

RelativeLayout does not support percentage of width and height for children. Use LinearLayout with android:layout_weight attribute.

2 RelativeLayouts in one layout

I've decided to use 2 RelativeLayouts for my app, one Layout for one portion of child Views on the screen to the left, the other for child Views to go to the right.
The problem is I don't know how to lay them out in XML so that the middle white space isn't included when I inflate my Layout.
This is what I want.
When I use 1 RelativeLayout, the middle white space is filled with the RelativeLayout, and I can't touch anything behind it.
Thank you very much for reading.

Do something similar to the following example.
This will create a LinearLayout with 2 RelativeLayouts using layout_weight to space the RelativeLayouts and then you can populate the RelativeLayouts with whatever you want.
The Buttons are just place holders for the example.
<?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="horizontal" >
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1" >
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="TEST1" />
</RelativeLayout>
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1" >
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="TEST2" />
</RelativeLayout>
</LinearLayout>