Develop Reference

Android UI: Size 2 view?

Good day everyone, currently i'm trying to make my first Android app, and then the first thing i realized, that idiotic XML UI designing.
I have this 2 view (button) and i'd like to make them so the first one fill the half of the parent (RelativeLayout) and the second one fills the other half of the parent...
My Code is:
<Button
android:id="#+id/Top1"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:layout_toLeftOf="#id/Top2"
android:text="top1"/>
<Button
android:id="#+id/Top2"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_alignParentRight="true"
android:layout_toRightOf="#id/Top1"
android:text="TOP2"/>
The problem, that i'm get this error:
"No resource found that matches the given name (at 'layout_toLeftOf' with value '#id/Top2')."
It seems, that not even Android want to use XML.
Like an old C program where if a method is written below the call, it will give an error...
So i have 2 question:
1: How to solve this problem in the XML?
2: Or can i avoid this XML designing, and use code-like design like in C# ?

There are a few ways you can go about this and I provided you with two ways to have buttons aligned side by side.:
Use a LinearLayout with orientation set as horizontal
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/btn_container">
<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="Left Button"
android:layout_weight="1"
android:id="#+id/btn_left" />
<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="Right Button"
android:id="#+id/btn_right" />
</LinearLayout>
Use a RelativeLayout and an extra View to align your buttons.
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<View
android:id="#+id/strut"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_centerHorizontal="true" />
<Button
android:id="#+id/btn_left"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignRight="#id/strut"
android:text="Left Button" />
<Button
android:id="#+id/btn_right"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_alignLeft="#id/strut"
android:layout_alignParentRight="true"
android:text="Right Button" />
</RelativeLayout>

You are correct, Top2 needs to be defined first in the XML before you can refer to it. That being said, if all you are doing is putting 2 buttons next to each other and have them fill the parent, you should consider using a LinearLayout. Order is important there, too: for horizontal orientation the children are laid out left to right, for vertical they are laid out top to bottom.

Create 4 ImageButtons at bottom of the layout

I am trying to display 4 ImageButtons at the bottom of the layout. I am able to get only 3 ImageButtons. The fourth ImageButton is not visible. and here is my code for that.
I am using Relative Layout for to display the application.
<ImageButton
android:id="#+id/Button1"
android:layout_weight="1.0"
android:layout_gravity="bottom"
android:layout_alignParentBottom="true"
android:longClickable="true"
android:layout_width="wrap_content"
android:layout_height="75sp"
android:background="#android:color/transparent"
android:src="#drawable/imagebutton2"/>
<ImageButton
android:id="#+id/Button2"
android:layout_gravity="bottom"
android:layout_toRightOf="#+id/Button1"
android:layout_width="wrap_content"
android:layout_height="75sp"
android:background="#android:color/transparent"
android:src="#drawable/imagebutton1"
android:layout_weight="1.0"
android:layout_marginLeft="2dp"
android:longClickable="true"/>
<ImageButton
android:id="#+id/Button3"
android:layout_gravity="bottom"
android:layout_toRightOf="#+id/Button2"
android:layout_height="75sp"
android:layout_width="wrap_content"
android:layout_weight="1.0"
android:background="#android:color/transparent"
android:src="#drawable/imagebutton1"
android:layout_marginLeft="2dp"
android:longClickable="true"/>
<ImageButton
android:id="#+id/Button4"
android:layout_gravity="bottom"
android:layout_height="75sp"
android:layout_width="wrap_content"
android:layout_weight="1.0"
android:background="#android:color/transparent"
android:src="#drawable/imagebutton1"
android:layout_marginLeft="2dp"
android:longClickable="true"
android:layout_alignParentRight="true"/>

Put it in a LinearLayout with weights and align this LinearLayout tot he bottom of the parent like this:
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:layout_alignParentBottom="true" >
<ImageButton
android:id="#+id/ib1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1" />
<ImageButton
android:id="#+id/ib2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1" />
<ImageButton
android:id="#+id/ib3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1" />
<ImageButton
android:id="#+id/ib4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1" />
</LinearLayout>
Note that this method will decrease the performance somewhat.

First you need to remove this from your ImageButton attributes if you want to keep using RelativeLayout as their parent layout:
android:layout_weight="1.0"
It is used in LinearLayout, Lint should be giving you a warning about it (invalid layout param in RelativeLayout).
If you want your 4 buttons to show in the bottom of the screen you need to include
android:layout_alignParentBottom="true"
in all 4 ImageButtons, I tried the xml you provide and only the 1st button is showing in the bottom.
And last but not least, if you want your button to have the same size to have some design consistency, I would suggest putting them in a horizontal LinearLayout with
android:layout_alignParentBottom="true"
android:layout_width="fill_parent"
and configure the ImageButtons with
android:layout_width="0dp"
android:layout_weight="1.0"
then include that LinearLayout in your RelativeLayout.
Another thing : since you're using
android:layout_width="wrap_content"
for your ImageButtons, you need to make sure the image is not too wide, otherwise some of your buttons might not be shown on screen because the first one(s) is taking too much space, leaving the last one(s) to the right of your screen.
On a side note, I hope you're not trying to make a iOS-style lower tab bar, this is frowned upon in Android, more info here ...
Have a good one !

Like some people say, in the last button, you don't have android:layout_toRightOf = "#id/Button3" so it's going to be in the top of the layout.
Other way to do this that I usually do is:
android:layout_toRightOf = "#id/Button1"
android:layout_alignbottom = #id/Button1"
It's going to align with the bottom of the button1. I do this because sometimes this button isn't align with the other one, depends of the layout.

At the last ImageButton you don't have:
android:layout_toRightOf="#+id/Button3"
You will need this if you want it to be at the bottom.
I would also suggest that you remove some of your code:
android:layout_gravity="bottom"
android:layout_weight="1.0"
This only works in FrameLayout or LinearLayout.
If you want to know for sure every ImageButton is at the bottom of the screen use what you used for the first button:
android:layout_alignParentBottom="true"

button placement in a linear layout

I have a linear layout with several buttons in it. The button images are all the same size and have the same attributes... except for one button. This one button has a smaller font size. All the buttons except for this one are in a perfect line exactly the way I want. For some reason, the button with the smaller font appears a little lower on the screen than the other buttons. I'm having a hard time wrapping my head around the idea of a button that requires less space taking up additional space.
Might someone give me a hint on what to read up on?
EDIT
Here's main.xml (seems like SO filters some of it, all the important stuff is here...)
<ScrollView android:id="#+id/scroll"
android:layout_width="match_parent"
android:layout_height="300px">
<TextView
android:id="#+id/the_text_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:typeface="monospace"
android:textSize="9pt"
android:background="#color/paper"
android:paddingLeft="20dp"
android:paddingBottom="20dp"
android:textColor="#color/type"
/>
</ScrollView>
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<Button style="#style/ASR33_button"
android:tag="Y"
android:text="Y"
/>
<Button style="#style/ASR33_button"
android:tag="N"
android:text="N"
/>
<Button style="#style/ASR33_button"
android:tag="E"
android:text="E"
/>
<Button style="#style/ASR33_button"
android:tag="W"
android:text="W"
/>
<Button style="#style/ASR33_button"
android:tag="S"
android:text="S"
/>
<Button style="#style/ASR33_button"
android:tag="F"
android:text="F"
/>
<Button style="#style/ASR33_button"
android:tag="R"
android:text="R"
/>
<Button style="#style/ASR33_button"
android:tag="M"
android:text="M"
/>
<Button style="#style/ASR33_button"
android:tag="T"
android:text="T"
/>
<Button style="#style/ASR33_button"
android:onClick="onEnterButtonClicked"
android:textSize="6pt"
android:text="RE-\nTURN"
/>
<Button style="#style/ASR33_button"
android:tag="U"
android:text="U"
/>
</LinearLayout>
<LinearLayout
android:orientation="horizontal"
android:layout_marginTop="10dp"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="#+id/instructions"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:textSize="9pt"
android:paddingLeft="10dp"
android:typeface="normal"
android:text="Commands: (Y)es, (N)o, (N)orth, (E)ast, (W)est, (S)outh, (M)ap, (ST)atus, (Fight), (R)un, (SU)icide. All commands must be followed by RETURN."
/>
</LinearLayout>
The one that's wonky is the 2nd from the bottom, with the different onclick event. The style has 11pt for the character size. If I use it (and a 1 letter button name, like the others) it behaves. But that's not what the ASR33 'enter' key has on it. So if I reduce the font size to say 6 pt, the weirdness happens.
The style can be seen here.
Again, just reading references or ideas please, I can figure it out if I have a word or two to search on. It's hard to know what you don't know...
RESOLUTION
Anurag has it right, see his answer below. Here's an excerpt of the updated LinearLayout:
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:baselineAligned="false">

maybe the re sizing has happened due to the wrap_content property of your button. so what you should do is have a fixed height to the linear layout holding all the buttons while its with is set to fill parents.
and inside the linear layout let individual buttons have height set to wrap content which will give all the buttons the same height as that of the linear layout and also set the attribute android:adjustViewBounds="true" for the small button. this attribute will resize your image button to maintain the aspect ratio. i hope this helps.
EDIT:
So here is the solution to your problem, something that was caused due to the base alignment property of the linear layout. A horizontal LinearLayout aligns the baselines of all its child controls by default. So the first line of text in your multi-line button is vertically aligned with the single line of text in the other buttons. set android:baselineAligned="false" on the LinearLayout. This worked perfectly on my HTC.

Center multiple items in a RelativeLayout without putting them in a container?

I have a RelativeLayout containing a pair of side-by-side buttons, which I want to be centered within the layout. I could just put the buttons in a LinearLayout and center that in the RelativeLayout, but I want to keep my xml as clean as possible.
Here's what I tried, this just puts the "apply" button in the center and the "undo" button to the left of it:
<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginTop="15sp">
<TextView
android:id="#+id/instructions"
android:text="#string/instructions"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="15sp"
android:layout_centerHorizontal="true"
/>
<Button
android:id="#+id/apply"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:text="#string/apply"
android:textSize="20sp"
android:layout_below="#id/instructions"
/>
<Button
android:id="#+id/undo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:text="#string/undo"
android:textSize="20sp"
android:layout_toLeftOf="#id/apply"
android:layout_below="#id/instructions"
/>
</RelativeLayout>

android:gravity will align the content inside the view or layout it is used on.
android:layout_gravity will align the view or layout inside of his parent.
So adding
android:gravity="center"
to your RelativeLayout should do the trick...
Like this:
<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:layout_marginTop="15sp">
</RelativeLayout>

Here is an extension of BrainCrash's answer. It is a non nested option that groups and centers all three horizontally and vertically. In addition, it takes the top TextView and centers it horizontally across both buttons. If desired, you can then center the text within the TextView with android:gravity="center". I also removed the margins, added color, and set the RelativeLayout height to fill_parent to highlight the layout. Tested on API 11.
<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="center"
android:background="#android:color/black"
>
<TextView
android:id="#+id/instructions"
android:text="TEST"
android:textSize="20sp"
android:background="#android:color/darker_gray"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_alignLeft="#+id/undo"
android:layout_alignRight="#+id/apply"
android:gravity="center"
/>
<Button
android:id="#+id/apply"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:text="APPLY"
android:textSize="20sp"
android:layout_below="#id/instructions"
/>
<Button
android:id="#+id/undo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:text="UNDO"
android:textSize="20sp"
android:layout_toLeftOf="#id/apply"
android:layout_below="#id/instructions"
/>
</RelativeLayout>

android:layout_gravity="center"
will almost give what you're looking for.

Here is a combination of the above answer's that solved my specific situation:
Centering two separate labels within a layout that also includes a button in the left most position of the same layout (button, label, label, from left to right, where the labels are centered relative to the layout containing all three views - that is, the button doesn't push the labels off center).
I solved this by nesting two RelativeLayout's, where the outer most layout included the
Button and an Inner-RelativeLayout.
The Inner-RelativeLayout contained the two text labels (TextView's).
Here is a snippet that provides the details of how the centering and other layout stuff was done:
see: RelativeLayout Gravity not applied? and
Gravity and layout_gravity on Android
for the difference's between gravity and layout_gravity.
Tweak the paddingLeft on the btn_button1 Button to see that the TextView's do not move.
(My apologies to havexz for the downvotes. I was too hasty in thinking that just b/c your suggestions didn't solve the exact question being ask, that they do help to solve very similar situations (the answer here solves a very specific situation, and only the combination of all these answer's solved my problem. I tried upvoting, but it won't let me unless I edit the answer's, which I don't want to do.)
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/rl_outer"
android:layout_width="fill_parent"
android:layout_height="50dip"
android:background="#FF0000FF">
<Button
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/btn_button1"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:background="#FF00FF00"
android:text="<"
android:textSize="20sp"
android:paddingLeft="40dip"/>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/rl_inner"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:background="#FFFF00FF"
android:layout_centerInParent="true"
android:gravity="center">
<TextView
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/tv_text1"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:background="#FF505050"
android:textSize="20sp"
android:textColor="#FFFFFFFF"
android:text="Complaint #"
android:gravity="center"/>
<TextView
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/tv_text2"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:background="#FF505050"
android:textSize="20sp"
android:textColor="#FFFFFFFF"
android:layout_toRightOf="#id/tv_text1"
android:gravity="center"/>
</RelativeLayout>
</RelativeLayout>

LinearLayout is a good option. Other than that there are options like create an invisible view and center that and then align left button to the left it and right on the right of it. BUT those are just work arounds.

LinearLayout text wrap problem when having two buttons of same size plus one stretched in the center

Looks like there's a plenty of questions about centering, same size etc, but so far I didn't find the exactly my case so I dare to ask :)
What I need is a layout of three buttons like this:
[ previous ][*select*] [ next ]
where [previous] and [next] buttons are of the same size (i.e. in this case, size of the [previous] button as it is bigger), and the [*select*] button should stretch to occupy all of the available width.
Following the hints of making two buttons in LinearLayout same sized, i came up with the following xml file:
<LinearLayout
android:id="#+id/button_bar"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:orientation="horizontal" >
<Button
android:layout_width="0dip"
android:layout_height="fill_parent"
android:layout_weight="1"
android:text="Previous" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="2"
android:text="Select" />
<Button
android:layout_width="0dip"
android:layout_height="fill_parent"
android:layout_weight="1"
android:text="Next" />
</LinearLayout>
This almost works :)
Except one thing: instead of making Next button to match the size of Previous button, android makes Previous button to be the size of the Next :)
And because of this the text "Previous" gets wrapped in two lines, like
Previ
ous
Dunno if this is a bug or not, but can you advice me a workaround or some another way to achive the desired layout?
Thank you!

I'd suggest using a RelativeLayout
<RelativeLayout
android:id="#+id/buttons"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:clickable="false">
<Button
android:id="#+id/previous"
android:layout_width="30dp"
android:layout_height="wrap_content"
android:text="Previous"
android:layout_alignParentLeft="true"/>
<Button
android:id="#+id/next"
android:layout_width="30dp"
android:layout_height="wrap_content"
android:text="Next"
android:layout_alignParentRight="true"/>
<Button
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Select"
android:layout_toRightOf="#id/previous"
android:layout_toLeftOf="#id/next" />
</RelativeLayout>
This should work.

If you are including "android:layout_weight" you should give either "android:layout_width" or "android:layout_height" as "fill_parent"
modify your code like this
<LinearLayout
android:id="#+id/button_bar"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:orientation="horizontal" >
<Button
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="2"
android:text="Previous" />
<Button
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="1.5"
android:text="Select" />
<Button
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="2"
android:text="Next" />

In that sort of case I would go for a TableLayout, in which you have one row, and a weight of 1 for EACH button. and the stretchColumn attribute put to column 1. Does this make any difference?

I'm not sure if you can match a size to some other besides by doing this in code. The easiest solution is probably adjusting the previous and next button widths in dp/sp units until they look good and have the select button be the only one with the layout_weight attribute.