Develop Reference

Can't support multiple screen sizes

I have just created a new resource folder in
\src\main\res\layout\layout-large
that contains the activity_main-large.xml with the following code:
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="LARGE" />
But when I run the app on a large screen device it still loads the defalut activity and shows "Hello World!" that I have put in
\src\main\res\layout\activity_main.xml
How should I fix that? I already read about this on the internet but I wrote the code in the correct way so what is the problem?

To have different ressources
they need to have the same name, and
they need to be in the correct folder
Your other configurations are on the same level, so rename your large layout and move it to
\src\main\res\layout-large\activity_main.xml
This will make it available for large devices.

R doesn't generate button

I've just finished to do the layout I want, and even although I saved everything, when I try to find by id the button, the button I'm looking for is missing.. Both the button's I have.. I've checked in the R class, under the ID, and it seems it doesn't sees' the buttons. Doesn't generate them? I dunno.. Any way, it happens every time I use relative layout!! Is there any connection? It works with TableLayout and with linear layout.. Only with relative layout it make's problems.
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#drawable/Background" >
<TextView
android:id="#+id/corpTag"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:text="#string/corpTag"
android:textColor="#color/White" />
<Button
android:id="#+id/addBusinessButton"
style="#android:style/ButtonBar"
android:layout_width="200dp"
android:layout_height="25dp"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="208dp"
android:text="#string/addYourBusiness" />
<Button
android:id="#+id/searchBusinessButton"
style="#android:style/ButtonBar"
android:layout_width="200dp"
android:layout_height="25dp"
android:layout_alignBottom="#+id/addBusinessButton"
android:layout_alignLeft="#+id/addBusinessButton"
android:layout_marginBottom="36dp"
android:text="#string/searchBusiness" />

I found this happening to me with a broken layout. No need to be worry. I am trying my best to giving you the solution
Solution
Make sure that anything the R. links to is not broken. Fix all errors in your XML files. If anything in the ADKs are broken, R will not regenerate.
If you somehow hit something and created import android.R in your activity, remove it.
Run Project -> Clean. This will delete and regenerate R and BuildConfig.
Make sure Project -> Build Automatically is ticked. If not, build it manually via Menu -> Project -> Build Project .
Wait a few seconds for the errors to disappear.

This problem isn't related to relative layout, but is actually set on the background because Android drwable is case-sensitive and now allows you any capital letters for image or layout. Rename your image name or drwable name to "background" instead of Background."
Here is the problem with set background name:
android:background="#drawable/Background"

It might be the Android Style ButtonBar. It isn't available for every API level. So if you have a low minSDK, it's not going to build and Eclipse/IntelliJ should give you an error message in its error pane.
The rule given by Google, is that you should always define your own resources. If you want to use a resource that is in the Android name space, that's fine, but you should copy it first and package it with your apk, because that's the only way you can be assured that it will always be bundled with your application.
And yes, I realize many people and many tutorials on the web don't do it that way, but that's because most people are lazy.

Missing or Incorrect images and backgrounds randomly throughout app lifecycle

I was hoping someone here might have an idea what causes this sort of behaviour:
Throughout my application, in seemingly random places and in random conditions I'm observing this strange UI issue. Images are on occasion being loaded black (with the correct bounds) or with the incorrect image source (again, with the correct bounds). This effects ImageViews and has effected android:background tags with references to colour resources.
My application relies on 6 library projects, it runs Native Code via a Service and Activities in the App use GlSurfaceViews (although, not all Activities which display the problem contain OpenGL components). The problem could I suppose be from any of these places or a combination of them through using large amounts of memory.
You can see this behaviour in the following screen shots:
This is actually a 6 or so pixel wide column separator image which has been incorrectly drawn into my ImageView (the ImageView seems to have correctly sized itself).
When going out of the Application and then back in again (repeatedly) it instead appeared (and remained) like so:
After a Force Clear and a Clear App Data it returned to the correct format:
As you can also see the Magnifying Glass image next to it is displaying fine in each of these. The problems with these missing/incorrect images and backgrounds seems to happen randomly, throughout the application lifecycle, and I've been unable to find a way of reproducing it.
The layouts for these images are nothing special, I'm not doing anything funny during the rendering lifecycle (i'm not overriding onDraw() or onMeasure() or the like). The source of these images aren't being set dynamically but via the XML.
As you can see from the above example, it's not a build issue as it occurs between app lifecycles not between installs. It's also happening on different devices, Samsung 8.9, Acer Iconia Tab, Motarola XOOM,
It seems to me to be some sort of error with the reference table, could it perhaps have been nudged by my native code? Or is it an effect of me in some stages of the application using too much memory?
Here's the XML source for the above example:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/browseProgressWrapper"
android:layout_width="match_parent"
android:layout_height="#dimen/actionbar_compat_height"
android:orientation="horizontal">
<RelativeLayout android:layout_width="#dimen/search_bar_width"
android:layout_height="match_parent">
<EditText android:id="#+id/browseFilter"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginTop="4dp"
android:layout_marginLeft="5dp"
android:imeOptions="actionSearch"
android:background="#drawable/edit_text_blue"
android:maxLength="30"/>
<ImageView android:id="#+id/clearSearch"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_centerVertical="true"
android:src="#drawable/ic_input_delete"
android:layout_marginRight="5dp"/>
</RelativeLayout>
<ImageView android:id="#+id/browseFilterButton"
android:src="#drawable/ic_menu_search"
android:scaleType="center"
android:layout_width="#dimen/actionbar_compat_height"
android:layout_height="#dimen/actionbar_compat_height"
android:layout_gravity="center_vertical"
android:minWidth="#dimen/actionbar_compat_height"/>
</LinearLayout>
A more full description of the code / layout surrounding another such occurrence I happened to get the screenshot for:
I have a "Settings" Activity which restarts my app after saving new settings details. It does this by stopping a Service, calling a new Activity (the Splash Activity) and finishing itself:
mConfiguration.save();
mConfiguration = new Configuration(Configuration.getInstance());
getActivity().stopService(new Intent(getActivity(), NativeService.class));
getActivity().finish();
startActivity(new Intent(getActivity(), SplashActivity.class));
Most of the time (and on most devices) this works fine, the Splash Activity contains an image which loads correctly. Sometimes though on some devices the Splash Activity loads either an incorrect resource (what my testers refer as "an upside down Nike tick") or just a blank box (as seen below). Does anyone know why?
Here is the Layout for the Splash page, as you can see it's pretty simple, no surprises:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/ContentBackgroundColor"
android:orientation="vertical" >
<View
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_weight="2" />
<ImageView
android:id="#+id/image"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:src="#drawable/manager_android_400" />
<View
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_weight="1" />
<ProgressBar
style="#android:style/Widget.ProgressBar.Large"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal" />
<View
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_weight="2" />
</LinearLayout>
Theory tested and debunct:
I've theorised that this could be a processor/memory issue where the Layout isn't being drawn fully before the Splash screen exits and moves onto the next Activity so I put in this piece of code:
image = (ImageView) findViewById(R.id.image);
image.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
image.getViewTreeObserver().removeGlobalOnLayoutListener(this);
moveToStartScreen.start();
}
});
The hope was the code above would make sure the Image is definitely loaded before moving onto the Start page but seems to have had no observable effect.
Another Theory
I was also wondering if this could be being caused by the R.id / R.colour / R.drawable resources some how being currupted in program execution? Does anyone know why that might happen.
Could my native code be running rampant on some memory addresses that Android isn't correctly allocating?
Has anybody noticed this before - or perhaps know why this behaviour occurs?

Graeme, I had almost the same problem and found out that it was a reported bug of the android plattform. It was corrected in the 3.0 version I think. Which API are you compiling with? Try to build with the last available api and be sure to compile with JDK 1.6
If your problem is related to this bug, this should fix the problem.

This is a simple problem of refresh, clean, and rebuild.
Images in your various drawable folders or resource id indices are out of sequence because they were either changed outside of the eclipse IDE (via external source control such as GIT, SVN or other edits) and not refreshed in the eclipse navigator. Or, the files may have been updated in a library project upon which your UI Activity depends.
I have found that although .java file dependencies are propagated throughout the system, this is not always the case for resources such as images and .xml files.
The solution is fairly simple, clean everything, refresh all of your projects, and rebuild. The stretched or black edges should be gone.
Note: The predominant manifestation of this problem occurs when 9-patch images become treated like standard .png images. This means that they get stretched in a linear manner across the image instead of just at the edges. To me, this explains your 'Torn/Stretched' example. I have seen similar often. Another common manifestation is that text strings occasionally get displayed with the wrong resources!

Drawable not showing up

I have a fairly simple xml file that has an image button in it. The image shows up fine on the Graphical Layout xml designer, shows up fine when I run a development build, but as soon as I create the signed apk file and run it, the image no longer shows up. It's just an empty button. I can't think of a reason why, any ideas? The xml file looks like this:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/navigation_root"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
<TextView
android:id="#+id/navigation_text"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="5dp"
android:text="TextView"
android:textAppearance="?android:attr/textAppearanceLarge" />
<SeekBar
android:id="#+id/navigation_seekbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:layout_weight="1"
android:padding="5dp" />
<LinearLayout
android:id="#+id/linearLayout1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="5dp" >
<ImageButton
android:id="#+id/part_select_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="#drawable/chapter_select" />
<Button
android:id="#+id/navigation_ok_button"
android:layout_width="75dp"
android:layout_height="match_parent"
android:layout_weight="1"
android:text="#string/ok" />
<Button
android:id="#+id/navigation_cancel_button"
android:layout_width="75dp"
android:layout_height="match_parent"
android:layout_weight="1"
android:text="#string/cancel" />
</LinearLayout>
</LinearLayout>
The image #drawable/chapter_select is a fairly small (41*41) png file that is in the res/drawable folder.

Seems like this is a bug with android, where sometimes the first image in the drawable folder doesn't show up. Added a dummy image called aaaa.png to the drawable folder and problem was solved. Found the answer here: ImageButton does not display a particular drawable

One of the reason is:
If you are using Vector file as a drawableLeft or drawableRight (or drawableStart or drawableEnd) in layout.xml, then you have to use androidx.appcompat.widget.AppCompatButton (formerly android.support.v7.widget.AppCompatButton) instead of Button.
Simple View like Button or Textview doesn't support Vector file as a drawableLeft or drawableRight (or drawableStart or drawableEnd) in my case.

Had the same issue and resolved it by removing all special characters. In my case it was dashes '-' in the filename:
background-720.png => background.png.

try to put the image in drawable-hdpi and drawable-mdpi folder
depends on what device you run you app , the image is searched in these folders...
But puting in drawable means that the image should be available everywhere, but somethimes (depends on your manifest settings) this could not be true, I mean you can turn of the compatibility mode.
also you can try dinamically at run time to set the image to the view
iv.setImageResource(R.drawable.somethig);

My situation was weird.Everything was correct until integrating FireBase Crash report to my Application.
I just added compile 'com.google.firebase:firebase-crash:11.0.1' & DrawableLeft vanished .When i went through the xml , noticed a warning (In lined below).
So added android:drawableStart & issue gone.
Still I am wondering about the relation of FireBase Crash reporting to the same.
Using left/right instead of start/end attributes Using Gravity#LEFT
and Gravity#RIGHT can lead to problems when a layout is rendered in
locales where text flows from right to left. Use Gravity#START and
Gravity#END instead.
Similarly, in XML gravity and layout_gravity attributes, use start
rather than left. For XML attributes such as paddingLeft and
layout_marginLeft, use paddingStart and layout_marginStart.
NOTE: If your minSdkVersion is less than 17, you should add both the
older left/right attributes as well as the new start/right attributes.
On older platforms, where RTL is not supported and the start/right
attributes are unknown and therefore ignored, you need the older
left/right attributes.
There is a separate lint check which catches that type of error.
(Note: For Gravity#LEFT and Gravity#START, you can use these constants
even when targeting older platforms, because the start bitmask is a
superset of the left bitmask. Therefore, you can use gravity="start"
rather than gravity="left|start".)

Check your image size. If you're using an unnecessarily large asset when actually deployed it might just not show despite looking correct in the designer.

Well ! in my case setting MinifyEnabled false and shrinkResources false is working fine now.
i was getting image from drawable. it was working pretty nice in debug version but after release version of apk it was showing sometime blank ImageView.
minifyEnabled false
shrinkResources true
**
See the Screenshots
**
Hope this may help anyone.

I had a similar problem where a drawable png was not showing up in Android Studio. Deleted the file and added it again in the drawable folder and it Worked for me.

Why is my image disappearing in landscape mode?

I have an image in portrait mode, which is displayed correctly. When I change the configuration to landscape, the image is not displayed.
Note that the LinearLayout, enclosing the ImageView is displayed right(I checked it by changing the background). But when I changed the background for the ImageView, the background was also not shown.
<LinearLayout android:layout_width="fill_parent" android:layout_height="fill_parent" android:padding="10dp" android:layout_weight="3">
<ImageView android:layout_width="wrap_content" android:layout_height="wrap_content" android:gravity="center_vertical" android:minHeight="48dp" android:minWidth="48dp" android:src="#drawable/xyz" android:id="#+id/img"/>

Do you have different files specified for portrait and landscape more? I.e., do you have a layout file with the same name in the layout folder as well as the layout-land folder? If so, make sure both files include the ImageView.

You are most likely specifying the file you want to display like
myImageView.setImage("myfile.jpg");
in your onCreate method.
Move this code to onResume (create onResume with the #Override if you do not already have it) This will fix your problem

OK, your layout file is unnecessarily large and complex. So let's try a couple of things-
First, try creating a simple version of your XML file that contains the barebones for displaying the image. If that works in both portrait and landscape, you know that the problem is not your activity or your image.
If the first step works, the next step would be to work on simplifying your layout file, there is a lot that could be pruned. It goes seven layers deep at points, that should almost never happen. Here is a good blog post by an Android engineer on better layout design. You can find similar resources elsewhere.