Develop Reference

cannot find symbol class DiskInfo and some other packages despite being present in SDK folder

I have an activity in which i have imported android.os.storage.DiskInfo and some other packages. Android Studio gives errors when trying to make the project saying:
error: cannot find symbol class DiskInfo
When i tried to resolve this problem i found out that all packages are present in folder $SDK-HOME\sources\android-24\android\os\storage but i don't know why Studio couldn't import them properly.
Is there anybody who have experienced problems in import and have solved it?
Thanks
p.s: i am using Android API 24

That is because of #hide in android source code. Actually Android is not allowing developers to use some classes. A solution is to use modified SDK which contains hidden classes. you can find it here https://github.com/anggrayudi/android-hidden-api

Check out : TargetSdk version and support package version.

Find import package for class in intellij idea

I have started using Android studio (intellij idea) for Android development (on Ubuntu 18.05) so I am very new to how it works and more used to visual studio :)
When I type a class name from Android API I note that ide mostly won't have suggestion as to which package to include. I find this to be a complete pain. For example if I type " ApiException aex;" IDE won't have any suggestions for what to include and will just report compile error.
I have various android libraries included in gradle and in the imports list so farily sure this class could be discovered by IDE (shouldn't this be java.lang.* or Google play services/GM's which I have in gradle?)
What is the easiest way to find which import I need for a class eg ApiException and is there a shortcut within Intellij to help with this?
Thank you

package com.android.datetimepicker.time does not exist?

When I cloned Android's default alarm in Anroid Open Source Project # https://android.googlesource.com/platform/packages/apps/DeskClock/ and tried to run it on Android Studio I got the following error:
package com.android.datetimepicker.time does not exist
cannot find symbol class TimePickerDialog
cannot find symbol class RadialPickerLayout <anonymous
com.android.deskclock.alarms.TimePickerCompat$TimerPickerPreL$1> is
not abstract and does not override abstract method
processTimeSet(int,int) in OnTimeSetListener
Please help in any way. Thank you.

After a week of frustration, I was able to clone the default alarm app and get rid of the above DateTimePicker errors mentioned above by injecting the dependency to the gradle by:
compile 'com.github.citux:datetimepicker:0.2.0'
Thanks to the good people out there (https://github.com/CiTuX/datetimepicker) who have cloned and distributed as a gradle dependency of the framework used in Android Open Source Project # https://android.googlesource.com/platform/frameworks/opt/datetimepicker
Hope this will help some who works on cloned Android Open Source Project.

Neither of those classes exist in the Android SDK. There is a
TimePickerDialog, as others have noted, in a different package.
There is a RadialPickerLayout in the Android source code, and you
are welcome to try to use it.
Really, you should be talking to whoever wrote this Android project
and asking them where they were planning on getting those classes
from.
Here is the main answer

How to add Crosswalk project to Android studio?

I am trying out android crosswalk project. I am having problems adding crosswalk webview to andriod studio though. I am not sure where I am going wrong nor do I understand most terminology yet.
I read https://crosswalk-project.org/documentation/embedding_crosswalk.html but I refers to https://developer.android.com/tools/sdk/eclipse-adt.html which is no longer supported. This seems to be outdated but I tried anyway with Android Studio 1.2.2.
I tried making a project with https://crosswalk-project.org/documentation/downloads.html Android webview (ARM) 13.42.319.11 as told in the documention. I am not sure what is meant with 'open ADT' but I assumed Android Studio instead of the plugin of eclipse. I opened from an 'existing android studio project' (the download unzipped). But didn't come across the option 'set root directory'.
I then tried to create a new android studio project and ran it. It showed the basic hello wold example on my phone. Then I followed the remaining steps by pasting in the code they provided. I ran it again and got 3 errors:
Error:(3, 22) error: package org.xwalk.core does not exist
Error:(9, 13) error: cannot find symbol class XWalkView
Error:(15, 23) error: cannot find symbol class XWalkView
I am not sure what to do from here as this is all very new to me.
Basically I am trying to run there example but can't figure out why the import isn't working.

I am having the same problem but I finally fixed it by placing the xwalk_core_library.jar in the libs folder, together with arm64-v8a and x86_64 subfolders and I have removed compile 'org.xwalk:xwalk_core_library:x.x.x.x' from dependecies.

Updated Links 19-07-2016
maven {
url 'https://download.01.org/crosswalk/releases/crosswalk/android/maven2'
}
And In dependencies add this
compile 'org.xwalk:xwalk_core_library_beta:9.38.208.8'

com.android.internal.telephony error

I have been learning "Sim Toolkit" in android. I had imported the sample project from this link.
But this file needs another import of "com.android.internal.telephony.cat". i couldn't find any jar files or libraries. When i tried to import code of packages from this link
Im not able to done it. Help me to fix this friends.
Thanks in advance.

You can't.
It's a hidden library and not part of Android public SDK.
In future, go to this link and search for Android Java packages, method names, etc. If the result returned is not what you searched for, then it's not part of the Android public SDK available to developers.
Or, you can just download the Android source codes via the Android SDK Manager and manually search for what you want.