Develop Reference

Detect if Material You is present in device

So, my boss asked me to analyze how to implement Material You colors starting from Android 12. I've been researching for it and every blog of every page about "how to do it" tells you that, you need to hold down at home screen, then go to "Wallpapers & Style" and change your wallpaper. There is an issue, though.
I remember that while Android 12 was in Beta, it was supporting Material You colors. However (I assume) after the official release, this support has been removed, because I am unable to find the option. Here is what it looks like when I hold down while at home screen:
It says "Wallpapers" and when I click on it, it does not open a menu called Wallpaper & style, it just redirects to Live Wallpapers. I've unable to find the wallpaper colors option on the official Android 12 release. However, it is present on the upcoming API 32 (Android 13 I believe) emulator.
Upon researching a little bit, I've found out that the system generates the wallpaper colors under the system resources such as system_accent1_600 etc. which are available starting from API 31 (more info here). This does work when I use an API 32 emulator which is in beta, but it defaults to something else (a shade of blue on accent colors, and shades of gray on neutral, a.k.a background colors) that I haven't figured out where from on an API 31 official emulator.
Here is the question:
Is Material You colors officially supported starting from Android 12 (API 31)? If yes, then why am I not able to find it on Android's official emulator?
Also, is it possible to detect if the device supports Material You colors with different options?

I think this is what you are looking for:
public static boolean isDynamicColorAvailable()
{
return VERSION.SDK_INT >= VERSION_CODES.S && DYNAMIC_COLOR_SUPPORTED_MANUFACTURERS.contains(Build.MANUFACTURER.toLowerCase());
}
Found this in DynamicColors class in com.google.android.material.color
You can simply call it like this:
boolean isdca = DynamicColors.isDynamicColorAvailable();
I hope this answers the last part.

1. Is Material You colors officially supported starting from Android 12 (API 31)?
Yes! But it based how the ROM implements. If you using Pixel, the you can change the color via the built wallpaper app. But if you're using AOSP, sine there is not an official way in UI to user to change it.
Check out this doc: https://gist.github.com/zhaofengli/232f5a3d33113871ad61491629886084
2. If yes, then why am I not able to find it on Android's official emulator?
It looks like Google removed it from the mirror. The previous mirror had this feature.
3. Also, is it possible to detect if the device supports Material You colors?
Since Android 12 supports Material You officially, so you can just check the api version simply.
But, according to the second point, some systems still don't support it, so you can use the method com.google.android.material.color.DynamicColors#isDynamicColorAvailable. This is the definitive method used by Material Design, depending on the SDK version and phone manufacturer.
https://cs.github.com/material-components/material-components-android/blob/2ae3ca42985722900f53de9d9a1ef61c143767eb/lib/java/com/google/android/material/color/DynamicColors.java#L279-L289
4. What is the correct way to implement Material You?
XML way: Follow the official doc: https://m3.material.io/libraries/mdc-android/color-theming
Programmatically way:
Check out my app's code:
val Context.colorOnPrimary: Int
get() {
return when {
DynamicColors.isDynamicColorAvailable() -> {
getColorFromAttr(R.attr.colorOnPrimary)
}
isNight() || !supportNight() -> {
ContextCompat.getColor(this, R.color.md_theme_dark_onPrimary)
}
else -> {
ContextCompat.getColor(this, R.color.md_theme_light_onPrimary)
}
}
}
#ColorInt
fun Context.getColorFromAttr(
#AttrRes attrColor: Int,
typedValue: TypedValue = TypedValue(),
resolveRefs: Boolean = true
): Int {
theme.resolveAttribute(attrColor, typedValue, resolveRefs)
return typedValue.data
}

Getting "no method with name='setBackground'" upon changing .Background property on legacy Android versions (<4.1)

Getting,
no method with name='setBackground' signature
or
no method with name='setBackground'
upon changing .Background property (to change the background visuals) in the app running on legacy Android versions (<4.1)
Any ideas on how to fix this?

As this question about Eclipse suggests, setBackground is problematic on API below level 16. Unlike covered in the question though, to work around the issue AND have your code Android 4.0-compatible, you'd want to change your background with the following (reproducible logic)
if (Build.VERSION.SdkInt < Android.OS.BuildVersionCodes.JellyBean)
{
layout.SetBackgroundDrawable(gd);
}
else
{
layout.Background = gd;
}

Setting a button background resource with a .png from internal storage

I have a button that I want to set the background of using a png file from internal storage. For android api 16 and up, this works fine:
filePath = getActivity().getFileStreamPath(colorCodes.get(i-1));
temp.setBackground(Drawable.createFromPath(filePath.toString()));
When running on an android tablet with 4.0.4, this part crashes the app with a nosuchmethod error (setBackground). After a little research, I see that setBackground is only available for api 16+. After looking around on SO and a few other places, it looks like I need to use setBackgroundDrawable (deprecated) or setBackgroundResource. I tried this:
filePath = getActivity().getFileStreamPath(colorCodes.get(i-1));
if (android.os.Build.VERSION.SDK_INT < 16) {
temp.setBackgroundDrawable(Drawable.createFromPath(filePath.toString()));
} else {
temp.setBackground(Drawable.createFromPath(filePath.toString()));
}
When logging it out, it shows that setBackgroundDrawable is running and not setBackground, but I get the same nosuchmethod error (setBackground).
The other option is setBackgroundResource, but it accepts an int and not a drawable. Can I convert from drawable to int for this purpose?
What can I do here to set the background of the button to a file in internal storage for APIs < 16?
Thanks.
***EDIT - ok, this is working. just missed a little part elsewhere in the code that had the same problem. However, is using a deprecated method really the only way?

Deprecation is a status applied to a computer software feature,
characteristic, or practice indicating it should be avoided, typically
because of it being superseded. The term is also sometimes used for a
feature, design, or practice that is permitted but no longer
recommended in other areas, such as hardware design or compliance to
building codes. (source link)
Now we can answer your question.
Before API level 16 there is a method named setBackgroundDrawable. After API Level 16 google decided to write a new method setBackground for same purpose and recommend us to use new method. (Reason of this may be found by googling.)
You can use setBackgroundDrawable method for all api levels. There aren't any constraint for this. But using new method setBackground is recommended after API Level 16.
But you can only use setBackground method for devices which is running on API Level 16 or higher. So if you only implement setBackground method in your code, you are going to get MethodNotFoundException for devices which run below API Level 16.
To sum up; it is a best practice(for me it is a must) to use new methods then deprecated ones with supportted api version check such as;
if (android.os.Build.VERSION.SDK_INT < 16) {
temp.setBackgroundDrawable(Drawable.createFromPath(filePath.toString()));
} else {
temp.setBackground(Drawable.createFromPath(filePath.toString()));
}

I am not quite sure whether it is the only way to achieve this but in my opinion it is the correct one. Because the annotation #Deprecated defines the method to be superseded (in most cases) it automatically implies you can (I would even say should) use it to address older versions which are the targeted versions of this method.

Conditional compiling in Android?

Is there any kind of conditional compiling for Android?
I had to make my project for Android 3 (API 11) just because ExifInterface has almost no useful attributes in Android 2.3 (API 10), despite the fact that it appeared in API 5 (!!??). I don't want to restrict my app to ICS users.
Thanks!

You can check dynamically the current API version of the device and do different stuff depending on that:
if(Build.VERSION.SDK_INT < 14) {
// Crappy stuff for old devices
}
else {
// Do awesome stuff on ICS
}
But be careful that if you need to instantiate classes that are not available for all APIs then you should do it in a runnable or in a separate wrapper class, e.g:
if(Build.VERSION.SDK_INT < 14) {
// Crappy stuff for old devices
}
else {
// Do awesome stuff on ICS
new Runnable() {
new AmazingClassAvailableOnICS();
(...)
}.run();
}

import android.annotation.TargetApi;
and then use annotations:
#TargetApi(11)
public void methodUsesAPI11()
{
...
Using this trick does a very simple thing: it allows compiling some code which contains API level 11 calls (classes, methods, etc) and still set android:minSdkVersion="8" in the manifest. Nothing more, nothing else.
The rest is up to you. You must check platform version before you call methodUsesAPI11() or you handle exceptions in order to prevent app crash and perform other action on older platforms.

Checking Build.VERSION.SDK_INT or using annotations should suffice, however, this link I'd bookmarked might be relevant to your case:
http://android-developers.blogspot.com/2010/07/how-to-have-your-cupcake-and-eat-it-too.html?m=1
You can use what they describe there to have classes that may not be compatible, but will never be loaded. It's not conditional compilation, but it may be what you need, however, it is a bit more complex.

TextView.getAlpha doesnt exist in Android

I want to get current alpha of textview i am using the following code but i am getting an error that
java.lang.NoSuchMethodError: android.widget.TextView.getAlpha
Please guide me.

This method since API Level 11. Check your API version.

View.getAlpha() only exists since API level 11. You are trying to running your code on a too-old version of Android.
If you absolutely require this functionality, then update your app's minSdkVersion in AndroidManifest.xml to prevent it running on older Android versions. If you can live without it, do a runtime check to see if the API level is high enough.

you can use Alpha method like below
Textview tv_password;
tv_password =(TextView) findviewById(R.id.tv1);
tv_password.getBackground().setAlpha(50);
you can't use getAlpha() method with Textview

View.getAlpha() available from API level 11.But if you want to use this on older api then you may use NineOldAndroids library available for using the Honeycomb (Android 3.0) animation API on all versions of the platform back to 1.0!
So use need to change for e.g.
mAlpha = mView.getAlpha();
to
mAlpha = ViewHelper.getAlpha(mView);
where mView is your view.
Note : Don't forget to import com.nineoldandroids.view.ViewHelper;