Develop Reference

Android Standard UI development for hdpi

I am relatively new to android. I want to develop an UI which works fine on 2 hpdi devices.
For example lets say on these two devices
Nexus 9
Size 8.86"
Resolution 2560x1600
Density xhdpi
Nexus 10
Size 10.05"
Resolution 2560x1600
Density xhdpi
As seen above both have different screen size and different resolution but density is the same.
My understanding is one layout should work perfectly on both devices, but unfortunately that is not the case. I see differences. Can someone please suggest what changes i should make.
Adding below the portion of the code(xml) which is giving me a problem.
<RelativeLayout
android:id="#+id/rl1"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="0.2" >
<customSeekBar
android:id="#+id/abc1"
android:layout_width="wrap_content"
android:layout_height="300dp"
android:layout_marginTop="40dp"
android:thumb="#drawable/eqthumb"
android:progressDrawable="#drawable/progress_eq"
android:max="19"
android:progress="10" />
<TextView
android:id="#+id/abc2 "
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_alignTop="#+id/ abc1"
android:textColor="#FFFFFFFF"
android:layout_marginTop="-10dp"
android:textStyle="bold"
android:text="300"
android:singleLine="true"
android:ellipsize="marquee"
android:textAppearance="?android:attr/textAppearanceSmall" />
<TextView
android:id="#+id/abc3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="#+id/ abc1"
android:text="0 dB"
android:textColor="#FFFFFFFF"
android:textStyle="bold"
android:singleLine="true"
android:layout_marginTop="-5dp"
android:ellipsize="marquee"
android:textAppearance="?android:attr/textAppearanceSmall" />
</RelativeLayout>
Thank you.

Density is only one part of your layouts though. These devices have different aspect ratios so available device independent pixel (dip or just dp) differs.
So your available width and height differs, but sure logical screen density is the same.
Having said that, android's layouts are rather flexible/adaptable and regardless of screen density. Your layout might need to compensate for different widths or heights though. Just as it might want/need to change due to portrait or landscape mode, different aspect ratios (a potential issue with these two devices) has the same difference.
So you are incorrect in assuming that your layout differs a lot due to hdpi/xhdpi/xxhdpi etc. You might want to qualify your layouts on available screen width or similar (sw720dp for example) instead if needed.
Nexus 9 has a logical screen density of: 1024 x 768 dip
Nexus 10 has a logical screen density of: 1280 x 800 dip
Having said that, your particular layout issue needs your specific xml layouts to be explained. For many layouts those two devices should be able to look the same.
Note: Your device data is off. Nexus 9 is 2048 x 1536 pixels and has an aspect ratio that's 4:3 mind you, compared to 16:10 for the Nexus 10. Both fall in the xhdpi bucket though for resource qualifiers etc. Physical screen density is 288 for the Nexus 9 and 300 for Nexus 10.

As seen above both have different screen size and different resolution but density is the same. My understanding is one layout should work perfectly on both devices
That's not true, you are building on top of this wrong premise. Simply put:
Devices with different screen sizes, but same density, will always work with the same layout
False: different screen sizes (in inches) mean you probably will have to adjust your views. So, provide different layouts, or at least different dimensions.
Devices with different densities, but similar screen sizes, should always work with the same layout
True: if the screen size is the same, a 40dp button will cover the same portion of screen in both devices. That's because dps are density independent pixels, and allow us to work on all densities out there with a single value.
I suggest you read this official resource, that should clear your mind. In the very first bullet list, we read:
Provide different layouts for different screen sizes
Provide different bitmap drawables for different screen densities
As you can see, there's no Provide different layouts for different screen densities, which was the premise of your question. That's just something you don't do usually, it makes no sense if you use (and understand) dps.

android different dimens not working

I have four dimens.xml files in my values folder and I have different values for different dimens.xml files.
for example, in dimens.xml(hdpi) u_video_width is 306dp and dimens.xml(xhdpi)u_video_width is 404dp.but this values not working, because when i run my app in Nexus S (480X800) hdpi model genymotion
This is what my View looks like:
[![This is what my View looks like][1]][1]
As I said in hdpi dimens folder, I have 302dp but I have different width when I run my app (in XML activity file)
this is a my XML code
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#D53362">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_centerVertical="true"
android:layout_centerHorizontal="true">
<VideoView
android:layout_width="#dimen/u_video_width"
android:layout_height="#dimen/u_video_height"
android:id="#+id/video_view"
android:layout_centerVertical="true"
android:layout_centerHorizontal="true" />
</RelativeLayout>
This is a my dimens xml files
Nexus S has 480X800 resolution and i want to my VideoView to have 302dp in hdpi resolution and another resolution--another dpi how I can solve my problem?

To make same dimension appear the same on higher dpi devices android multiply these dimension with a constant ie
for mdpi it is 1x
hdpi 1.5x
xhdpi 2x
xxhdpi 3x
So in your case it is 306 * 1.5 = 459px
reset of the space (14dp ~35 px) is available on both sides of VideoView
Please refer android developer page
At least this is what I understood. Hope it helps you.

As far as I've understood, it seems it's working right. Your screen is 480px wide and your VideoView is 306dp(in a hdpi screen ~453px), and as it's centered, it remains a bit of margin.
If you want the same dp in another resolution, just remove u_video_width from the other files.

Android Resize images according to the screen size of the device

I hope someone can help me.
I have days looking for a way to Resize images in android according to the screen size of the device.
Sometimes the picture is fine but when used in a slightly larger image comes to be very small and not resized or adapted to the screen size.
For there I saw that for every image that wanted to join the project, was to add image in different sizes, Example: 80x80, 160x160,220x220,320xx320 (each has the same name.) and that helped resized.
Or did so but not me. sometimes the image is totally distorted.
This is the code I use for ImageView
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/inicio"
android:background="#drawable/inicio1"
android:layout_centerHorizontal="true"
android:layout_marginTop="40dp"
android:layout_below="#+id/imageView"
/>
that I can do to make the image take an appropriate size according to the size of the screen.
Thank You

do this
<ImageView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/inicio"
android:background="#drawable/inicio1"
android:layout_centerHorizontal="true"
android:layout_marginTop="40dp"
android:scaleType:"fitXY"
android:layout_below="#+id/imageView"
/>

You can use different sized images in different folders.Put same image with different sizes i.e small size image for ldpi folder,slightly bigger for mdpi.You can refer the documentation here
hdpi,ldpi,mdpi,xhdpi and xxhdpi

Have you put the images into their respective sizefolders? Like Android tells you here: http://developer.android.com/guide/practices/screens_support.html
Basically in the drawable folder you should have another set of folders with the names ldpi, mdpi, hdpi, xhdpi, xxhdpi, xxxhdpi. In these folders you should put your image with the same name but different image size. Look at the link for the different sizes suggested.

density pixels(dp) is not working fine for all resolutions

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#color/gray"
android:orientation="vertical" >
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="#color/darkgray"
android:gravity="center"
android:orientation="horizontal" >
<Button
android:id="#+id/attenders"
android:layout_width="110dp"
android:layout_height="40dp"
android:layout_gravity="center"
android:background="#color/gray"
android:layout_marginRight="8dp"
android:text="Attenders" />
<Button
android:id="#+id/send"
android:layout_width="110dp"
android:layout_height="40dp"
android:layout_marginLeft="8dp"
android:layout_gravity="center"
android:background="#color/gray"
android:text="Send IM" />
</LinearLayout>
</LinearLayout>
this is my code but the dp is not working fine for all screen resolutions.
suggestions plz, plz tell me if i am doing anything wrong

problem is that when i use dp for setting height or width of a button
it does not gets fits to all resolutions i-e on small screens it looks
big and on big screens it looks small, whereas i know that when we use
dp for setting height and width of any component it automatically
converts/adjusts according to screen resolution
What I understand from this is that you thought using dp instead of px (or in, or cm) will magically work such that they will all have the same physical size on all devices, regardless of that device's density (ppi).
That's not the case.
dp, or dip, as explained here, is
An abstract unit that is based on the physical density of the screen.
These units are relative to a 160 dpi (dots per inch) screen, on which
1dp is roughly equal to 1px.
A screen with more dpi (denser, meaning more pixels are packed into a square area of the screen), will essentially draw a physically smaller image compared to a screen that has 160dpi when tasked to draw the same, say, 100x100 dp image.
When running on a higher density screen, the number of pixels used to
draw 1dp is scaled up by a factor appropriate for the screen's dpi.
Solution
There are two easy ways to have your app look proportionally the same on different screen sizes.
The first is to use different layout folders (layout-ldpi, layout-mdpi, etc.). This technique is well-explained here. A much more recommended way would be to use different style values for each density, so you can still maintain one layout folder and refer to the styles instead for measurement. This can be done using the same technique, but instead you will have values-ldpi, values-mdpi, etc. This is useful for having standard sized UI elements across screen sizes.
The other way is to use weights all over your layout. Weights adjust automatically regardless of screen size of density. This will help a lot if you want, say, three columns that have varying width -- you can easily use weights to tell the layout that column A needs to occupy 40% of the available width of the screen, and B and C will have 30% each. This is useful for having a standard layout across screen sizes.
A clean-looking, nicely coded app will implement both.

It is beacause you are giving fixed dimensions which can only be fit for a particular screen size which you are using. So try avoiding static dimensions and make use of match_parent,wrap_content and fill_parent so that you can get your layout fit for every screen size.

Android screen size resolution

My app works perfectly in resolution 480x800. If I keep the 480x800 resolution but change the screen size to for example 2.7 inches, 3.7 inches or 5.4 inches it still is perfect. But when I change the resolution to for example 640x1066 all the ImageButtons is too small and in the wrong place in all screen sizes... I have created ImageButtons in all four folders(drawable-l, m, h, xh) but still the buttons is not in the correct size..
<ImageButton
android:id="#+id/ib1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="6dp"
android:layout_marginTop="433dp"
android:background="#drawable/imagebutton1" />
<ImageButton
android:id="#+id/ib2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="188dp"
android:layout_marginTop="436dp"
android:background="#drawable/imagebutton2" />
NOTE: My problem is not when I change screen size, but when I change screen resolution.

I would really like to see some code.
If you use RelativeLayout with attributes like android:layout_width and android:layout_height and specify values in dp (density pixels) e.g. android:layout_height="40dp" it should work just fine.
Please try to share some code with us.

Make sure that your assets that you have in your ldpi, mdpi, hdpi and xhdpi folders are scaled correctly to accommodate the diff. resolutions. I accidentally scaled some assets incorrectly, and although they were in the correct folders..gave me some bad results
http://developer.android.com/guide/practices/screens_support.html