Android设计支持库-版本号和Gradle错误

Question

I am trying to implement the CoordinatorLayout and Snackbar into my first app. I know that I need to add an Android design support library as a dependency in the build.gradle file but I am getting the following error in Android Studio 2.3.1:

Failed to resolve: com.android.support.design:25.3.1

Install Repository and sync project

Open File

I think there are 2 possible problems:

1. I have specified the wrong version number - If 25.3.1 is not correct, what is the version number that I should be using? It's not the same as the appcompat version? I have searched the web but can't seem to find the answer anywhere. I have tried older version numbers like 24.0.0 and 22.2.0 but it doesn't work. I have Android Support Repository version 47.0.0 installed.
2. I haven't actually installed the Android design support library, because the error is telling me to install the repository? I read somewhere on SO that I just need to have the Android Support Repository installed - I do and it appears to be up to date?

Here are the dependencies in my build.gradle file:

dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
    exclude group: 'com.android.support', module: 'support-annotations'
})
compile 'com.android.support:appcompat-v7:25.3.1'
compile 'com.android.support.constraint:constraint-layout:1.0.2'
compile 'com.android.support.design:25.3.1'
testCompile 'junit:junit:4.12'
}

And in the activity_main.xml layout file:

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    ...
</android.support.design.widget.CoordinatorLayout>

I have found similar questions on SO with gradle build errors but the response is often something along the lines of the advice below which I don't understand, particularly step 3.

1. File -> Invalidate caches / Restart

2. Shutdown Android Studio

3. Rename/remove .gradle folder in the user home directory

4. Restart Android Studio let it download all the Gradle stuff it needs

5. Gradle build success !

6. Rebuild project.... success !

I would try this except I don't know where to find the .gradle folder?

Answer 1

You have the following line:

compile 'com.android.support.design:25.3.1'

It should be:

compile 'com.android.support:design:25.3.1'

Notice the ':' instead of '.' between 'support' and 'design'.

25.3.1 is the correct version at the moment.