Adding an Object to an Arraylist results in nullpointerexception : <p>I cannot add any (or maybe just the first?) Objects to my Arraylist</p>

<p>A Bikestore is an Object which contains a name and an Arraylist of all it's bikes</p>

<p>bikes have 3 different attributes (2 Strings, 1 double)</p>

<p>Bikes are added to the Store within an "addbiketocollection()" method and within this method I use the .add function.</p>

<pre><code> public class Bikes 
    String brand ;
String color;
double price;

Bike(String brand, String color, double price){
    this.brand = brand;
    this.color = color;
    this.price = price;
}

public class Bikestore {

String name;
ArrayList&lt;Bike&gt; Collection = new ArrayList&lt;&gt;();

Bikestore (String name, ArrayList&lt;Bike&gt; Collection){
    this.name = name;
    this.Collection = Collection;
}


public void AddBikeToCollection (Bike NewBike) {
    Collection.add(NewBike);


}

  Mainclass
    Bike Bike1 = new Bike ("Cube", "Black", 400);

    Bikestore SellingBikes = new Bikestore ("SellingBikes", null);

    SellingBikes.AddBikeToCollection(Bike1);

}
</code></pre>

<p>when I try to add bikes to the bikestore I get a nullpointerxception
Exception in thread "main" java.lang.NullPointerException</p>

<p>I have already googled my problem and watched some videos but none of these contained an arraylist with objects.</p>
