Returning get() method in put() method in a Hash Map

[Wpbops]

Hi, I'm new to the site and just have a quick question about a project I'm working on.
I'm making a Library catalogue program, and working on the checkoutItem() method. It's a method that checks out an item if not already checked out. If the book is not checked out, get() should return null.

/**
     * Return who has given book 
     * Null if not checked out.
     */
    public Patron whoHas(Item i)
    {
     return checkoutsMap.get(i);
    }

/**
    *Uses WhoHas() method for this
public boolean checkOutItem(Item i, Patron p)
    {
        if(whoHas(i))
            {
                return null;
            }
        checkoutsMap.put(i, p);  //Assign item variable to patron variable in the Hash Map
    
         
        
        
    }

Could anyone lend a hand?

-Wpbops

[pbrockway2]

if(whoHas(i)) {

What does the compiler have to say about this line?