error: class, interface, or enum expected [in DVD.java] In LeetCode arrays lesson

I’m new to Java so I was trying LeetCodes arrays lesson and I copied the code directly from the page and it returned an error in there own IDE does anyone know what is causing this?
Thanks.

DVD[] dvdCollection = new DVD[15];

// A simple definition for a DVD.
public class DVD {
    public String name;
    public int releaseYear;
    public String director;

    public DVD(String name, int releaseYear, String director) {
        this.name = name;
        this.releaseYear = releaseYear;
        this.director = director;
    }

    public String toString() {
        return this.name + ", directed by " + this.director + ", released in " + this.releaseYear;
    }
}

>Solution :

You must declare the array within a class

// A simple definition for a DVD.
public class DVD {
    public String name;
    public int releaseYear;
    public String director;

    //Move declaration within class
    DVD[] dvdCollection = new DVD[15];

    public DVD(String name, int releaseYear, String director) {
        this.name = name;
        this.releaseYear = releaseYear;
        this.director = director;
    }

    public String toString() {
        return this.name + ", directed by " + this.director + ", released in " + this.releaseYear;
    }
}