Develop Reference

My app looks horrible in older/smaller phone

I've been using my galaxy s9+ for creating good looking app, but now I tried with old galaxy s5, its very old and my app looks horrible in it. Is it just simply too old, or will this happen to newer, better resolution phones too?
My main problem is the main menu, that has plenty of space in s9+ but can't see last button in s5, do I need to do something differently? I've been using Relative layouts, and sometimes androidx.constraintlayout.widget.ConstraintLayout

SDP - a scalable size unit
https://github.com/intuit/sdp
This is the library I have been using for my app. Its easy and it automatically manage the size of layout and view.It changes dimension according to the screen size. Change all you dimension in _sdp.

I think it been answered before but I would like to share my idea or way to resolve text size problem over difference resolution devices. Many android developer sites suggest that we have to use sp unit for text size which will handle text size for difference resolution devices. But I am always unable to get the desired result. So I have found one solution which I am using from my last 4-5 projects and its working fine. As per my suggestion, you have to place the text size for each resolution devices, which is bit tedious work, but it will fulfill your requirement. Each developer has must listen about the ratio like 4:6:8:12 (h:xh:xxh:xxxh respectively). Now inside your project res folder you have to create 4 folder with dimens file e.g.
res/values-hdpi/dimens.xml
res/values-xhdpi/dimens.xml
res/values-xxhdpi/dimens.xml
res/values-xxxhdpi/dimens.xml
Now inside dimens.xml file you have to place text sizes. I am showing you code for values-hdpi, similarly you have to place code for other resolution values/dimens.xml file.
<?xml version="1.0" encoding="utf-8"?>
<resources>
<dimen name="text_size">4px</dimen>
</resources>
For other resolutions it is like xhdpi : 6px, xxhdpi : 8px, xxxhdpi : 12px. This is calculated with the ratio (3:4:6:8:12) I have written above. Lets discuss other text size example with above ratio. If you want to take text size of 12px in hdpi, then in other resolution it would be
hdpi : 12px
xhdpi : 18px
xxhdpi : 24px
xxxhdpi : 36px
This is the simple solution to implement required text size for all resolutions. I am not considering values-mdpi resolution devices here. If any one want to include text size for this resolution then ration is like 3:4:6:8:12. In any query please let me know. Hope it will help you people out.

yes.. as mentioned by Rajesh Kumar Sharma you can you this library https://github.com/intuit/sdp. I have used in so many projects.. & it works well...
good luck.

app's UI is not proper in a 220 dpi screen

hi I'm new in android developing and it's my first app.
I have made these folders in address : app\src\main\res for supporting multiple phone and tablet screens and put proper dimens.xml files in them.
values-ldpi
values-mdpi
values-hdpi
values-xhdpi
values-xxhdpi
values-xxxhdpi
values-sw600dp
values-sw768dp
values-sw800dp
first of all, are they complete or am I missing some screen sizes?
second, I've tested the app on several devices and it's working fine and has proper user interface in all phones but on the Galaxy Grand Prime which has a 5 inch 540 x 960 pixels display that means 220 dpi. this phone using hdpi dimens but UI is a bit messy.
The following pictures may make my point better :
Proper UI , as it is shown in other devices
VS
UI in galaxy grand prime 220 dpi display
as UI is completely OK in other devices, I thought I should make a specific dimens.xml file for that kind of dpi, so I made values-sw220dp. but after that other phones used this dimens instead of hdpi dimens and problem got worse because UI was fine in the galaxy phone and was not proper in other hdpi displays. and now I don't know what should I do.
can anyone help me in this issue?
at last sorry because of flaws in my english , as you can guess I'm not a native.

are they complete or i'm missing some screen sizes?
If you read the guides which I mentioned at the end of my answer you will find that there are very many possibilities of defining resources folders. I think nobody will want to implement all of them.
Usually you look at your app and then decide on maybe three or four screen sizes you want to support. I think "sw220dp" is important, if only to show a message that your app needs more space :-).
So there could well be three to five layout folders (sw220dp, sw320dp, maybe sw480dp, sw600dp, maybe sw820dp). If you need orientation-dependent layouts, then the number will be twice that much. (Why ? That's explained very well in the guides linked below)
You already know that there are different types of resources. Some of them do not depend on the screen resolution (e.g. layout files), some do (drawable resources).
So first of all you decide which screen sizes you want to support. Let's say they are "phone", "tablet" and "220dp". You create three layout files by the same name "my_activity.xml" and put them in three folders
for the really small window: res/layout-sw220dp
for the mobile phone: res/layout-sw320dp
for the tablet: res/layout-sw600dp
By the way, "sw" stands for smallest width which is the minimum length of the screen, no matter what the orientation is currently.
Now let's assume you have created three different layout files and all of them contain an ImageView like this:
<ImageView
android:layout_width="24dp"
android:layout_height="24dp"
android:src="#drawable/my_picture" />
This is where the screen resolution comes into play: 24dp is a size value in "density-independent pixels". It will be resolved depending on the screen resolution of the device. So you need different versions of my_picture.png, and for this you need different folders for drawables. They are named after the different categories for screen resolution so the runtime knows which png file to pick:
res/drawable/ldpi (although I read somewhere you can skip that because the pictures will be scaled down from hdpi nicely)
res/drawable (here go the resources for res/drawable-mdpi as well as every drawable resource for which resolution does not matter, e.g. drawables defined via xml files)
res/drawable-hdpi
res/drawable-xhdpi
res/drawable-xxhdpi
res/drawable-xxxhdpi
Helpful links:
Providing Resources
Supporting Multiple Screens

Different layout for 5 and 4 inch Android devices

I have an Android application with one layout file. I have different layout files for different densities, i.e., layout-hdpi, layout-mdpi, etc. I also have different dimens files in corresponding value directories (values-mdpi, values-hdpi, etc).
My problem is that I would like to use different layouts for 4 and 5 inch screen devices. I am testing on two physical a 4 inch and a 5 inch and both devices use the layout from the /res/layout folder and the dimens file from the /res/values-hdpi/ folder (in other words, they use the same resources).
Is there a way to make the 4 inch device use a different dimens.xml file - if not automatically, can this be done programmatically?

You can use something like layout-sw320dp or similar. This will differentiate layouts based on minimum display width.
Here is much more about it:
https://developer.android.com/guide/practices/screens_support.html#NewQualifiers

Density is not related to size, they tell you how many pixels there are in on square inch of screen, not how may inches of space there are in the screen. you should use size related resources. for example layout-w500dp folder would be used for screens that have at least 500dp of width.this should help

calculate dp for different screen for supporting multiple screens

I know there are many questions like this, I have read many blogs and questions on this and I am not satisfied by what I have understand.
I want to support multiple screens and resolutions like hdpi, xxxhdpi etc.
And i am using dimens.xml for this purpose. But m still unclear about how to calculate exact dp value for different screens.
For example if 48dp x 48dp ImageView is proper for hdpi device, what values should i define for xxhdpi device? Is there any fixed calulation just like there is for drawable images?
I am using these folder for trying to support multiple screens :
values-sw320dp-hdpi
values-sw320dp-xhdpi/xxhdpi/xxxhdpi
There are few problems I am facing currently
Though defining values in respective dimens.xml works almost for most of the devices, there are few devices which takes wrong values
For example I have Lg optimus G that is xhdpi device, but it reads values from values-sw320dp-xxxhdpi's dimens.xml instead of xhdpi one
I am not able to calculate the exact value for each resolution (hdpi,xhdpi etc), so the view which looks perfect in hdpi device, seems little large or small in xxxhdpi as I can't guess the value like if hdpi view size is 48dp then xxxhdpi should be of 64dp or something as I don't know the exact approach.
Also while searching for supporting different screens, I read many times about calculating dp at runtime based on density or calulating pixels etc.
I am too confused about all this. Please help me in understanding and learning the proper way of making responsive apps.

You can use resource qualifiers to specify different sizes for Views.
If you want the width of an ImageView to vary based on the size of the screen, create a new dimension in your dimens.xml file called image_view_width (for example).
This then essentially creates a copy of the dimens.xml but adding the 'Size' qualifier. This will create another version of the dimens.xmlfile, and any device that meets your specified qualifications will use that version of dimens.xml. You then add image_view_width to this new file and give it a different (smaller/bigger) value. You can do this as many times as you want and with as many different qualifiers as you want.
Finally, when you want to use this value in your layouts, you only have to type:
android:layout_width="#dimen/image_view_width"
and android will do the rest for you.
Hope this helps!

Android Text Scaling on different resolutions same density

I have 2 devices, a 1024x600 7" tablet hdpi running Gingerbread and a hub attached to a touchscreen which is 1920x1008 22" in size, hdpi running ICS. The Android OS seems to consider both as "large" (240dp).
So, they have the same actual density (240dpi), same generalized density (hdpi), same generalized size (large) but different actual size (7" vs 22")
The text and spacing dimensions that I specify for my layout work great on the 22", but then on the 7" they look enormous and dont fit on the screen.
I've tried using dp and sp, no difference as I think the problem is that Android sees these things as the same size / density. Does anyone have any recommendations on how I can be able to scale sizes appropriately?
This program wil also eventually need to be supported on a 4.5" handheld as well.
Thanks in advance.

Sorry, my previous answer was completely wrong = )
Ideally, you should be able to design for the 7" tablet and have your layout scale up to the TV. But if that doesn't work you should be able to use something like layout-sw1008dp. The "sw" prefix allows you to specify the minimum dimension of the smallest side of the screen - so in the case of a TV, the height.

I am also facing such problem in my application. But i found a good solution for this.
I have only one layout for tablet and directory name is layout-sw600dp.
Now, when part came to height and width problems, I have created several different values directory in which i place dimensions and font size and other stubs. So there will be no constant value in layout of tablet screen.
androd:layout_width:"60dp" // i drop this scenario
androd:layout_width:"#dimen/tab_width" // i used this scenario
and your values directory name will be like
values-xlarge
values-large
All the values will be fetched from your values directory. It will not create different layout, but one layout can be used multiple times.
See my stack answer which may help you.