Why does gradle say that it cannot resolve "com.android.support:support-annotations:23.1.1"?

Question

I am building an app called Shaking. Today I added some button libraries to the project, namely:

Bootstrap Buttons: https://android-arsenal.com/details/1/65

Flat Buttons: https://android-arsenal.com/details/1/68

I added the following in the dependencies block of build.gradle file:

compile 'com.beardedhen:androidbootstrap:2.0.1' //This is the bootstrap library
compile 'info.hoang8f:fbutton:1.0.5' //This is the flat buttons library

just like the webpages above have said.

Then an error pops up that says:

Error:Failed to resolve: com.android.support:support-annotations:23.1.1

After some time, I figured out that the bootstrap buttons library is causing the problem because if I comment the line out, no errors!

I tried closing Android Studio and opening it again and cleaning the project, rebuilding... It all did not work.

Then I found this question
I thought the problems that I am having is quite similar to that so I followed the steps suggested by the second answer. This time, another error occurred:

Error:failed to find target android-23 : C:\\Users\\User\\AppData\\Local\\Android\\sdk

I think I do not have SDK 23 installed.

I really want to know why this happens and how can I fix it!

Answer 1

Below is build.gradle of com.beardedhen:androidbootstrap:2.0.1:

apply plugin: 'com.android.library'
apply from: 'push.gradle'

android {
    compileSdkVersion 23
    buildToolsVersion "23.0.1"

    defaultConfig {
        minSdkVersion 11
        targetSdkVersion 23
        versionCode = Integer.parseInt(VERSION_CODE)
        versionName = VERSION_NAME
    }
}

dependencies {
    compile 'com.android.support:support-annotations:23.1.1'
}

You can see that compile 'com.android.support:support-annotations:23.1.1'.

Make sure that you have install android support library 23.1.1:

Answer 2

In build.grade module app add this:

implementation group: 'com.beardedhen', name: 'androidbootstrap', version: '2.3.2'