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android:navigationBarDividerColor requires API level 28

Previously, I implemented light and dark navigation bar, however now tags as android:navigationBarDividerColor and android:windowLightNavigationBar require API level 28 when they previously required API level 27.
It seems API level 28 does not even exist as next API level is called P.
Is there any solution to this problem? Thanks in advance.
UPDATE: it seems to work now on API 27 with latest support libraries

When the "next upcoming API" is still under development, its "name" is a letter (P in your case).
Once the final version of the API is available, the "name" is changed form a letter to a number (P to 28).
Final version of Android API 28 (former Android P) is available since early June 2018. Just use the SDK manager and you'll be able to download it ;-)
Note:
Sources for "Android SDK Platform xx" (28 in your case)" is not available right away. (not available ATTOW)It can takes a few weeks before they are available for download from the SDK manager.

Today I've updated compileSdkVersion, targetSdkVersion and buildToolsVersionfrom 27 to 28. Now I'm facing the same issue as #Teďourek described.
While it was working for me on 27, since the upgrade I now get lint errors:
Error: android:navigationBarDividerColor requires API level 28 (current min is 19)
Error: windowLightNavigationBar requires API level 28 (current min is 19)
This is strange because according to the docs for both attributes it says:
"added in API Level 27"
My temporary fix is to move the two style attributes to v28/styles.xml instead of v27/styles.xml
Since I would like to use lightNavBar + color also on Android 8.1.0 as previously, I would be happy if anyone knows a fix!

With compileSdkVersion and targetSdkVersion set to 29 it seems to be correct.
The XML properties tell me it was added in API level 27.
Only the Java Window properties are added in API level 28.

ArraySet in android.util and android.support.v4.util

What is the difference between
android.util.ArraySet
android.support.v4.util.ArraySet
All methods seem to be identical.

As the page indicates, android.util.ArraySet was added in API level 23. android.support.v4.util.ArraySet is a copy in the backwards-compatibility support library, which allows you to use the class on older devices as far back as API level 4 (increased to level 14 in recent releases).

Android 27: LogLogcatRule and RuleLoggingUtils replacement?

How does one test log output for Android classes. Prior to Android 27 LogLogcatRule and related classes like RuleLoggingUtils served these purposes, but it appears they were removed.

API target and min confusion

I am confused about the target build and sdk usage
Lets say I have this code
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT){
//do xyz
}
Let say that I built against API 19 (kitkat) and my target api in manifest is 19 and my minimum supported api is 9
Now if a device with API 9 runs the above code, will it crash? I expect the answer is yes becasuse it will not understand what Build.VERSION_CODES.KITKAT means. However, what's the point of the check above then in first place?
Please help clarify this
Thank you

It won't crash. Simply the code within the if won't be executed. Build.VERSION_CODES.KITKAT is a constant field, and as you can read here, the constant fields are replaced with the numbers themselves by the compiler.

lesser versions of android will use the support library, if the check for kit-kat fails, it will revert to the closest possibkle form that version supports.... via the support library...
you cannot run you app on anything less than the minimum version, but it will find a way to run with less than the target version as long as its aboe the minimum

No, it won't crash, because its Build.VERSION.SDK_INT value is 9. It simply will not enter inside your if clause. Only devices that have API version 19 or above will run your code inside the if. Build.VERSION_CODES.KITKAT is equal to 19.

The code you posted won't crash because the class Build is created and compiled for every build of your app (as the R file) depending of the target API you set in the manifest
As you setup your target API to 19, the Build class will contain the field Build.VERSION_CODES.KITKAT because it exists starting from API level 19.

Compatibility for Java library methods that require Android API level 9?

Some Java library methods like DecimalFormat.setRoundingMode have a #since 1.6 entry in their documentation.
/**
...
* #since 1.6
*/
public void setRoundingMode(RoundingMode roundingMode) {
...
}
When I tried to use this method compiled under Android 4.2.2 and JDK 1.6 with my android:minSdkVersion set to 7 as shown,
myNumberFormat.setRoundingMode(RoundingMode.DOWN);
Android Lint underlined setRoundingMode in red for me and told me that
Call requires API level 9 (current min is 7): java.text.NumberFormat#setRoundingMode
How and why can the Android API restrict which Java library methods I can and cannot use? I cleaned my project and the Lint error disappeared. My project compiled with no errors and ran on a device running Android 2.2.3 (API 8).
My program crashed with:
05-09 11:32:38.436: E/AndroidRuntime(2074): Caused by: java.lang.NoSuchMethodError: java.text.NumberFormat.setRoundingMode
The Android documentation confirms that setRoundingMode, copySign, and others were added in API level 9. Does that mean that devices running Android OS level 8 and below are specifically compiled/built with JDK 1.5?
And I can understand that. But is it impossible for the Android Support Library (or anything else) to allow us to use these methods?
Related to Rounding Half Up with Decimal Format in Android