Develop Reference

I can't change position of textview and buttons in layout editor

My layout preview doesn't show the action bar only the textviews and buttons I added and when I add a new button or textview, it just goes to the top left corner of the screen even though I tried using Relative and Constraint Layouts. I've tried using "Base.Theme.AppCompat.Light.DarkActionBar" but it doesn't solve it. I've had this issue since I installed android studio on my new PC.Here's a screenshot of my layout preview
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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">
<Button
android:id="#+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center"
android:text="Create Account" />
</RelativeLayout>

It's totally normal that your button is on the top left corner if you don't set its position.
If you add this to your Button:
android:layout_centerInParent="true"
Than your Button will be in the center of the root layout.

You can even use ConstraintLayout for this problem. With the help of constraint layout handles you can easily set the button to the centre position.constraint layout centering button
it can be done easily : join right handle first, then left handle, then top and bottom handle.
also with the help of this, layout will not be distorted on different screens

RelativeLayout takes all its space, even though I've set its height to "wrap_content"

Background
I have a RelativeLayout inside a FrameLayout/RelativeLayout (doesn't matter to me), which should be at the bottom of the screen (like a toolbar), and should hold a few views in it.
Its height is set to "wrap_content" and so does its child-views.
The child-views of this layout are : A textView that is on the left, and a Horizontal LinearLayout on the right with a few buttons.
The problem
It seems that no matter what I do, the textview is causing the RelativeLayout to take the whole space, instead of just its children.
The code
Here's the minimal XML content that causes this problem. I've removed the extra stuff (LinearLayout and its children, and also some attributes that don't matter) since they don't cause this problem in case I remove the TextView:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#FF000000" >
<!-- Here I've put some views that don't have any relation with the views below, so it doesn't have anything with do with the problem -->
<RelativeLayout
android:id="#+id/RelativeLayout1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:background="#drawable/vertical_gradient_transparent_to_black" >
<!-- Here I've put a LinearLayout that doesn't cause the problem, so I've removed it for simplicity-->
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"/>
</RelativeLayout>
</RelativeLayout>
I've tried many possible attributes, and also tried adding additional layouts to try to "fool" the RelativeLayout, but none of those have succeeded.
The question
Why does it occur?
A working solution would be to use a Horizontal LinearLayout (with a weight for the TextView ) instead RelativeLayout , but I still want to know why can't I use a RelativeLayout, and why it occurs. Also how to fix it while still using RelativeLayout.

From the RelativeLayout doc:
Class Overview
A Layout where the positions of the children can be described in relation to each other or to the parent.
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
Class documentation
Which is exactly your case. RelativeLayout can not do that.

I have encountered the same issue before, this might be caused by android:layout_alignParentBottom attribute.Maybe you can find another way to achieve your desired effect. See this for more information.

This is some kind of Strange issue. Maybe someone else has the explanation.
I found it working when i removed the line
android:layout_alignParentBottom="true"/>
and it also worked when i tried some like this
<TextView
android:layout_width="match_parent"
android:layout_alignParentTop="true"
android:layout_height="wrap_content"/>

Status bar always on screen

Good day (or evening, or night)
I'm developing an app for android and I'm very curious about one thing. I have an activity, where user chats with another, like "im" chat. There are an EditText on the bottom and some kind of actionbar on the top. What I need is when user enters a message and the software keyboard is on screen, my activity should move up, but the actionbar should still be "glued" to the top of the screen, because it has some valuable controls on it.
Again, that's not an ActionBar, but just a 48dp height layout in a parent vertical linear layout. So I need to know is there an easy way to prevent it from moving to the top, when the layout moves off the screen.
I tried to put everything in a FrameLayout and put this bar on top of it, but on keyboard opens it goes off the screen too...

On you Activity at AndroidManifest you should put this: android:windowSoftInputMode="adjustResize"

Use something like this:
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<com.myapp.MyActionBar
android:layout_width="match_parent"
android:layout_height="48dp"/>
<LinearLayout
android:id="#+id/mylayout"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1dp"/>
<!-- Add your edittext and button -->
</LinearLayout>
This will make sure the actionbar and edittext + button are allways on screen, and the mylayout takes up the rest of the screen. When your keyboard is shown, the mylayout will shrink.

Try adding android:windowSoftInputMode="adjustResize" to your activity in the manifest. This tells Android to completely resize your layout when the keyboard comes up, rather than pan it. Note that if there isn't enough room for the entire layout this still won't work. But you ought to be able to make it work if your top level layout is a RelativeLayout, with the edit text set to align bottom, the top bar to align top, and the middle section to fill_parent and be above the edit text and below the bar.

use a RelativeLayout as your base Layout and add android:layout_alignParentTop="true" to your action bar to keep it up
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<LinearLayout
android:id="#+id/action_bar_layout"
android:layout_width="match_parent"
android:layout_height="48dp"
android:layout_alignParentTop="true" >
</LinearLayout>
<TextView
android:id="#+id/text_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_centerInParent="true" />
</RelativeLayout>

unwanted side margins of my custom listview item layout

I'm getting some weird left and right side margins when using a custom listview item layout. They are margins (or at least not padding of the container), since the background doesn't extend to the edge.
In this layout, I'm using a simple vertical LinearLayout with a bunch of textviews and a progressbar. If I switch back the built-in simple_list_item_activated_1.xml, the margins disappear. The linear layout itself doesn't have any layout margins. I specifically stripped it of any attributes, leaving only the id, the layout_width="match_parent" and layout_height="wrap_content", and the margins were still there.
Is there anything I'm missing here?
A screenshot of the problem can be seen here:
Edit 1: #Grishu: As I've said earlier, these margins appear even with a very simple layout, such as this
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="#+id/some_text"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
I just typed this from memory, so it might contain syntax errors. But you get the idea.
Edit2: I just went over all my layouts. The problematic margin was set on one of the parent containers, thus it has nothing to do with list items. Sorry for the spam.

i had a similar problem with a listview item layout, it looked fine in the graphical layout in eclipse, i solved it by setting:
android:layout_margin="0dp"
android:padding="0dp"
in the main relative layout, hope this helps.

Using layout_gravity="bottom" to place at bottom of LinearLayout

I would like to place a layout on the bottom of a LinearLayout, but I can't seem to get it to work. I know that I can use RelativeLayout to do this, but I should be able to use LinearLayout, shouldn't I?
EDIT: Actually this is more confusing than I thought. The layout below is simplified. In reality, I'm using fragments on a pre-3.0 device, with the compatibility layer.
I used Hierarchy Viewer to examine what's going on, and found that an android.support.v4.app.NoSaveStateFrameLayout was added to my layout, and that layout has layout_height set to wrap_content. That seems to be what's causing my problem, but I haven't yet figured out how to fix it.
Specifically, why doesn't this work? Shouldn't the layout_gravity place it at the bottom?
<LinearLayout
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
... stuff here ...
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
android:orientation="horizontal">
... more stuff here ...
</LinearLayout>
</LinearLayout>
BTW, changing layout_height to fill_parent or setting layout_weight don't seem to work either. I just want to better understand what is going on, because clearly I'm missing something important. Thanks.

First of all nice question.
Android behaves we can say weird in the situation like this.
if you have selected your parent linear layout's orientation horizontal then you can set its child component at bottom by setting its layoug_gravity=bottom. suppose you have added 2 text views in that horizontal linear layout and second textview's layout_gravity is bottom then it will set to bottom but it work like it is set at bottom in other column then the first text view. NOTE : you can set textview's layout_gravity = "left" or "right" when its parent linearlayout is horizontal but you cant see its result.
Oppositely, if you have selected parent linearlayout's orientation vertical then you can set its child component at left or right by using layout_gravity. but the second textview will shown in you can say next row with left or right gravity as you have set. NOTE you can set textview's layout_gravity = "top" or "bottom" when its linear layout is vertical but you can not see its result.
Try to make sample xml design as i have stated above so you get better idea.
Strange but True!!! Try to understand this behavior. :)

Just add space between what you want at the bottom and all the rest:
<Space
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1"/>

So I resolved the problem. It's a two-part solution:
First, the way to do this without using LinearLayout is to provide weight to the element above so that it takes up all of the empty space. BTW, you can see this example in the API demos: http://developer.android.com/resources/samples/ApiDemos/res/layout/linear_layout_3.html
<LinearLayout
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
... stuff here ...
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:weight="1"/>
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
... more stuff here ...
</LinearLayout>
</LinearLayout>
This by itself didn't solve my problem, as I had a NoSaveStateFrameLayout with layout_width="wrap_content" as a parent view, and so I needed to get that fixed first. I'm using code based on the wonderful Google I/O App, and when I searched the code for NoSaveStateFrameLayout, I found this:
// For some reason, if we omit this, NoSaveStateFrameLayout thinks we are
// FILL_PARENT / WRAP_CONTENT, making the progress bar stick to the top of the activity.
mRootView.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT,
ViewGroup.LayoutParams.FILL_PARENT));
Thanks for an awesome comment Google!!! I added this into my source and everything worked great!
The moral of the story: Hierarchy Viewer and comments are your friends.

LinearLayout will just stack things as they are placed in there. Since it is vertical, it will keep placing items one after the next in a vertical manner. Can you change the android:gravity of the linearLayout and not the layout_gravity of the nested one and see if that works.
RelativeLayout of course should be the first way but you stated you didnt want to do that. Is there reason for that?

It could be that, as per https://stackoverflow.com/a/13366783/513038, you need to set the parent LinearLayout to have android:baselineAligned="false". Worked in my case.