Static Inner class returning null when instantiating

Question

I have a public class called Tournament which has a nested private static class called Team.

public class Tournament {

    private Team[] teams;
    private static int noOfTeams;
    private  Queue<Team> queue = new LinkedList<>();
    Team teamA,teamB,winner;


    public Tournament(int noOfTeams) 
    {
        this.noOfTeams = noOfTeams;     
        generateTeams();
    }


    private void generateTeams()    
    {


        for (int i = 0; i < noOfTeams; i++) 
        {       
            this.teams[i] = new Team();  // Returning Null here
            this.teams[i].setId(i);
            this.teams[i].setRank(i);       
            queue.add(this.teams[i]);
        }       

    }

}

So when I create an object of Tournament. The constructor calls the generateTeams() method.When I run this , it is returning a NullPointerException at the line: this.teams[i] = new Team(); (Which is highlighted in bold).

For some reason it is not instantiating the Team() object and hence assigning a null value to teams[i]

New to OOPS and nested classes. If possible explain in detail.

Thanks in advance.

Answer 1

You need to instantiate the array first

this.teams = new Team[noOfTeams];

for (int i = 0; i < noOfTeams; i++) 
{     
    this.teams[i] = new Team();   
    this.teams[i].setId(i);
    this.teams[i].setRank(i);       
    queue.add(this.teams[i]);
} 

But as you are adding Team Objects to a queue, why do you even need an Array?