Develop Reference

Inserting many views into one layout without them overflowing to the end of the screen

I'm looking for a way that I can dynamically add views into a layout (currently a LinearLayout) and that they won't overflow into the end of the screen and be hidden.
I can't use ScrollViews since it has to look like one sentence (It's a "fill the blanks" question).
I'm just looking for an idea on how to do this, not the code itself.
Thanks in advance, Shay.

If you are using linear layout than use linear layout with weights:
For example:
You have a LinearLayout with vertical orientation and you have 2 ImageViews inside it and you want these ImageViews always to take equal space.
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:weightSum="2"
android:orientation="vertical"
android:layout_gravity="center">
You can set the layout_weight of each ImageView to 1 and the weightSum in LinearLayout to 2 to achieve this.
<ImageView
android:layout_height="wrap_content"
android:layout_weight="1"
android:layout_height="0dp"/>
This will work correctly for any device without overflow into the end of the screen and be hidden

Android Centering the content

I'm a total beginner in Android layout, but I want to center the content vertically and horizontally.
So this book I'm reading says this:
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:background="#color/background"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:padding="30dip"
android:orientation="horizontal" >
<LinearLayout
android:orientation="vertical"
android:layout_height="wrap_content"
android:layout_width="fill_parent"
android:layout_gravity="center" >
...component.. etc...
This works and I think i get it, except Eclipse says:
This linearlayout or its parent is useless; transfer the background
attribute to the other view
But I do not understand this?

This linearlayout or its parent is useless; transfer the background
attribute to the other view
means that you can manage the entire layout by the parent it self, you are unnecessarily adding another LinearLayout which can degrade the layout performance
You can use android:gravity="center" instead of android:layout_gravity="center" which a child supplies to its parent.
Solution
you can combine your linear layouts as
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:background="#color/background"
android:orientation="vertical"
android:layout_height="wrap_content"
android:layout_width="fill_parent"
android:gravity="center"
android:padding="30dip"
>

add android:background parameter in both LinearLayout

This linearlayout or its parent is useless; transfer the background
attribute to the other view
This is a warning triggered when any Layout has only one child which is also a Layout. In your case LinearLayout. In these cases one of other can be removed without any problems. It is recommended to remove these redundant layouts. It is.. as it says just a warning, it wont cause any exception, but if you remove that redundant layout that will help improve overall performance

You should share your full code so that everyone get the whole scenario of your problem. Any way you can follow three way to do the things.
Approach One :
android:layout_centerInParent="true"
Above code will make your layout center horizontally and vertically.
Approach two :
And if you want to do individually.(May be needs sometimes)
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
Approach three :
android:gravity="center" (Though I see you have used. May be you have missed any point inside code).
Hope this will help you. Happy coding.

fill_parent in LinearLayout isn't being honored

After much research on both SO and google, I haven't seen any one with exactly the same problem I am experiencing, so here it is:
I recently redid the entire UI on an android app. For the most part, I made only cosmetic changes to each of the screens. They appear in the UI editor of eclipse perfectly as expected. However, directly after doing this, two of the screens stopped being laid out correctly on both all tested devices and the emulator.
Now, the big problem one these two screens was that the root level LinearLayout didn't appear to be actually honoring the fill_parent for either layout_height or layout_width. it looks like it's being measured as if it were set to wrap_content instead. It only takes up about 70% of the screen - which is just enough to wrap the individual elements inside the root LinearLayout. I would post an image, but as a new user, I am not allowed to.
The layout isn't stretching to fill the screen. Here's the code for layout, except that there are a few more in the LinearLayouts containing a TextView and an EditText.
<?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:background="#FF000000"
android:orientation="vertical" >
<TextView
style="#style/sans.white.16.bold"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:paddingTop="4dp"
android:text="#string/edit_account" />
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >
<com.teamunify.ondeck.widget.TUTextView
style="#style/sans.white.14"
android:layout_width="100dp"
android:layout_height="wrap_content"
android:text="#string/first_name" />
<com.teamunify.ondeck.widget.TUEditText
android:id="#+id/acc_editor_first"
android:layout_width="fill_parent"
android:layout_height="40dp"
android:selectAllOnFocus="true"
android:singleLine="true" />
</LinearLayout>
I think the root LinearLayout should be filling both height and width. I've used this same layout many MANY times in our app without problems. (A quick count revealed that I used 76 LinearLayouts in our app, and all but two of them are working.)
At first, I suspected that perhaps our custom classes measure was wrecking things, so I changed the layout to use all plain EditTexts, but there was no change. I double checked the activity, but it isn't doing anything except to load this xml. So, in desperation, I redid the layout like so:
<?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:background="#FF000000"
android:orientation="vertical" >
<TextView
style="#style/sans.white.16.bold"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center|top"
android:paddingTop="4dp"
android:text="#string/edit_account" />
</LinearLayout>
After that, The words Edit Account appear with a black background mashed into the upper left corner. Clearly, the LinearLayout isn't filling the parent.
Long story short, I am asking how to fix this so that the LinearLayout fills the screen as expected.
I am at a complete loss as to why this is happening, and I am certainly hoping that someone on SO has an idea. This has got me pulling my hair out!

Try setting fixed width and height for the root layout.
Then only you will be able to debug who is driving length and width. It is very much possible that parent activity or background activity is setting dimensions. Once you identify the root cause you can go back to original settings.
As of now from your code snippet given here, nothing wrong here

If you use a custom activity as a container to other activities for some reason (In our case, we were recreating the look of our iOS app, and needed a custom menu to show up along the button side of the screen) the window manager seems to get a bit confused with what the actual height and width of the nested activities should be. A call to fillparent or matchparent ends up wrapping the content instead.
We ended up changing the behavior of several methods in our container activity class to make this work.

Android RelativeLayout and height of wrap_content?

I am trying to make a selection ListActivity, similar to the one used to add shortcuts to the launcher screens. I have rolled my own header and footers, which I would like to be "sticky" at the top and bottom of the view when on screen. In order to do this, I am using a RelativeLayout with the header set to dock to top, footer set to dock to bottom, and the list set to go below the header and above the footer. In terms of the overall layout of the activity, this is rendering as I would expect. The header is sticky to the top, the footer is sticky to the bottom, and the list scrolls in between them.
One odd thing though happened when I switched to the RelativeLayout as my root. Please see the following screenshot:
I want my Activity's height to be wrap_content, so that the form is only as high as the content displayed in it, but once i switched to RelativeLayout, it seems to render the Activity effectively as fill_parent, taking up the whole screen, even though the content doesn't warrant it. Notice that there are not enough list items to fill the screen, which with the fill_parent style, is leaving a bunch of whitespace between the end of the list, and the footer. I was setting my height's via styles - which worked fine with LinearLayout, but seems to be ignored now. So I tried hard-coding the height directly on the RelativeLayout, but it still doesn't work and still renders as fill_parent.
Here is my layout code:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
style="#style/GroupsList"
android:layout_height="wrap_content">
<FrameLayout android:layout_height="wrap_content"
android:layout_width="fill_parent"
android:id="#+id/hdrGroups"
android:layout_alignParentTop="true">
<include layout="#layout/title"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
</include>
</FrameLayout>
<FrameLayout style="#style/MyFooter"
android:layout_height="wrap_content"
android:layout_width="fill_parent"
android:layout_alignParentBottom="true"
android:id="#+id/ftrGroups">
<ImageView style="#style/CloseButton"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:src="#drawable/add"
android:id="#+id/imgGroupsAdd"
android:clickable="true">
</ImageView>
</FrameLayout>
<ListView android:divider="#9f9f9f"
android:id="#+id/android:list"
android:choiceMode="singleChoice"
android:dividerHeight="1dp"
android:layout_height="wrap_content"
android:layout_width="fill_parent"
android:layout_below="#id/hdrGroups"
android:layout_above="#id/ftrGroups">
</ListView>
<TextView android:text="#string/browser_no_groups"
style="#style/ListedItemB"
android:id="#+id/android:empty"
android:layout_height="wrap_content"
android:layout_above="#id/ftrGroups"
android:layout_below="#id/hdrGroups"
android:layout_width="fill_parent">
</TextView>
</RelativeLayout>
All layout is done via XML, ... I am not doing any layout in code.
How can I get the sticky header and footer while also having the activity as a whole behave in a wrap_content mode for its height? Is there some other way I should be going about this instead of a RelativeLayout?

According to the developer documentation your desired behaviour is not possible for Relative layout ;
"Note that you cannot have a circular dependency between the size of
the RelativeLayout and the position of its children. For example, you
cannot have a RelativeLayout whose height is set to WRAP_CONTENT and a
child set to ALIGN_PARENT_BOTTOM."
RelativeLayout
To solve your problem you could maybe try to use a linear layout, set to wrap_content and set max height via code to screen height.
You can get the screen height as described here : get screen height

I just change my RelativeLayout in FrameLayout and all starts to work

android:layout_gravity effect in main.xml?

I have 4 buttons in a horizontal linear layout. I'd like the right edge of the 4th button to align with the right edge of the linear layout (equal to screen width) I've tried using android:layout_gravity="right" but it doesn't work - the right button is to the right of the 3rd one but not right aligned . Am I missing something obvious?
main.xml with only the relevant layout params only is:
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<LinearLayout
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
<Button
android:layout_height="fill_parent"
android:layout_width="wrap_content">
<Button SAME LAYOUT AS BUTTON 1>
<Button SAME LAYOUT AS BUTTON 1>
<Button
android:layout_height="fill_parent"
android:layout_width="wrap_content"
android:layout_gravity="right" />
</LinearLayout>
</LinearLayout>
This doesn't seem to match the stated behaviour for layout_gravity in the SDK reference :"Defines how to place the view, both its x- and y-axis, within its parent view group."

I know this isn't really the proper answer to your question, but you should really consider using RelativeLayout instead of LinearLayout. It scales better to different phone screen resolutions, and you can place the buttons in the correct order by using the layout_toRightOf and layout_alignParentRight attributes in your XML (or layout_above, layout_alignParentTop, etc.). Using gravity in a linear layout won't really behave as you expect because Android is still attempting to place the widgets in a fixed position.
RelativeLayout is a bit more of a pain to get working than LinearLayout, but it's worth the trouble and is also the one which Google recommends using. Once you get the hang of it, they are very convenient to work with.