FloatingActionButton class could not be instantiated

Question

After taking a look at the new methods in Material Design, I tried to implement a Floating Action Button in an app. However, I am getting this error in my preview (Previewing Android version 21):

The following classes could not be instantiated:
- android.support.design.widget.FloatingActionButton
(First paragraph of error)
java.lang.NullPointerException
at android.support.v4.graphics.drawable.DrawableCompatLollipop.setTintList(DrawableCompatLollipop.java:56)
at android.support.v4.graphics.drawable.DrawableCompat$LollipopDrawableImpl.setTintList(DrawableCompat.java:145)
at android.support.v4.graphics.drawable.DrawableCompat.setTintList(DrawableCompat.java:270)
etc...

Anyone have any idea? This is my build.gradle:

android {
compileSdkVersion 22
buildToolsVersion "22.0.1"
classpath 'com.android.tools.build:gradle:1.2.3'


defaultConfig {
    applicationId "owensetiawan.tutorials.fab"
    minSdkVersion 15
    targetSdkVersion 22
    versionCode 1
    versionName "1.0"
}
buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
}
}

dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
compile 'com.android.support:appcompat-v7:22.2.0'
compile 'com.android.support:design:22.2.0'
}

It would be absolutely fantastic if someone could help me shed some light on my problem.

Answer 1

Hey i got the same problem with the instantiated of design library and solved it by this

Step 1 > code for fab

    <android.support.design.widget.FloatingActionButton
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_gravity="bottom"
      android:clickable="true"
      android:src="@drawable/search"
      app:backgroundTint="@color/color_fav"
      app:borderWidth="0dp"
      android:layout_alignParentBottom="true"
      android:layout_alignParentEnd="true"
      />

step 2 > dependency

    compile 'com.android.support:appcompat-v7:22.2.1'
    compile 'com.android.support:recyclerview-v7:22.2.1'
    compile 'com.android.support:design:22.2.1'
    compile "com.android.support:support-v4:22.2.1"

step 3 > the main step for above problem

easy one:- go to your xml and click on preview and in the bar in preview select AP1 21

Answer 2

Make sure that the VERSION for AppCompat Library and the Design Support Library is the same. This is mostly an internal dependency conflict, keeping both versions same fixed it for me :-

compile 'com.android.support:appcompat-v7:24.2.1'
compile 'com.android.support:design:24.2.1'