Unwanted app crash by using SwipeableCardStack from wenchaojiang - crash

Question

I wanted to add the AndroidSwipeableCardStack written by wenchaojiang.
So I added everything like it is saidin the description but when I start the app it just crashes:
So it would be very nice if someone could help me:
This is my Layout File:
<?xml version="1.0" encoding="utf-8"?>
<RealtiveLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/bildergalerie"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="16dp"
android:paddingLeft ="16dp"
android:paddingRight ="16dp"
android:paddingTop = "16dp"
tools:context="com.example.felixjhn.info_tab.Bildergalerie">
<com.wenchao.cardstack.CardStack
android:id="#+id/card_stack"
android:padding="20dp"
android:clipChildren="false"
android:clipToPadding="false"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
</RealtiveLayout>
And this is my main class:
package com.example.felixjhn.info_tab;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import com.wenchao.cardstack.CardStack;
public class Bildergalerie extends AppCompatActivity implements
CardStack.CardEventListener {
private CardStack card_stack;
private CardActivity card_adpater;
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.bildergalerie);
initImages();
card_stack = (CardStack)findViewById(R.id.card_stack);
card_stack.setContentResource(R.layout.card_layout);
card_stack.setStackMargin(20);
card_stack.setAdapter(card_adpater);
card_stack.setListener(this);
}
private void initImages() {
card_adpater = new CardActivity(getApplicationContext(),0);
card_adpater.add(R.drawable.king);
card_adpater.add(R.drawable.queen);
card_adpater.add(R.drawable.king1);
card_adpater.add(R.drawable.queen1);
}
#Override
public boolean swipeEnd(int i, float v) {
return (v>300)?true:false;
}
#Override
public boolean swipeStart(int i, float v) {
return false;
}
#Override
public boolean swipeContinue(int i, float v, float v1) {
return false;
}
#Override
public void discarded(int i, int i1) {
}
#Override
public void topCardTapped() {
}
}
And this is my CardActivity class:
public class CardActivity extends ArrayAdapter<Integer> {
public CardActivity(Context context, int resource){
super(context,resource);
}
#NonNull
#Override
public View getView(int position, View convertView, ViewGroup parent){
ImageView imgView = (ImageView)convertView.findViewById(R.id.image_content);
imgView.setImageResource(getItem(position));
return convertView;
}
}
Here I importet the repositories:
allprojects {
repositories {
jcenter()
maven{url"https://jitpack.io"}
And this is my build.gradle(module:app) file where I also added everything what is needed:
apply plugin: 'com.android.application'
android {
compileSdkVersion 26
buildToolsVersion "26.0.1"
defaultConfig {
applicationId "com.example.felixjhn.info_tab"
minSdkVersion 19
targetSdkVersion 26
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
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-v7:26.+'
compile 'com.android.support:design:26.+'
testCompile 'junit:junit:4.12'
//Add Library
compile 'com.github.wenchaojiang:AndroidSwipeableCardStack:0.1.0'
}