Can not call the method from interface
<p>Hi guys i have a program that is library management program</p>

<p>I have a method called borrowHolding(holdingId)throws BalanceLow, InvalidHolding
i am calling that from model interface which calls facade class which pass method call to library class but from here the method definition is declared in interface borrower, Another interface Member extends this borrower interface and then the AbstractMember implements the borrowHoling method may small coding snippets clear:</p>

<p>All import are correct and each class and interface are separated in different calss.</p>

<pre><code>  public interface LMSModel {
    public void borrowHolding(int holdingId)
                throws InsufficientCreditException, MultipleBorrowingException;
    }


    public class LMSFacade implements LMSModel {
    private Library lib = new Library();
        private Member member;
    public void borrowHolding(int holdingId)
                throws InsufficientCreditException, MultipleBorrowingException {
            // TODO Auto-generated method stub
            lib.borrowHolding(holdingId);

        }
    }


    public class Library {
    public Member member;
    public void borrowHolding(int holdingId) throws InsufficientCreditException, MultipleBorrowingException {

            member.borrowHolding(holdingId);
        }
    }


        public interface Member extends Borrower{
    public abstract Holding[] getCurrentHoldings(); 
        public abstract double getMaxCredit();  
        public abstract void resetCredit();
        public abstract String getFullName();
        public abstract String getMemberId();

    }


    public abstract class AbstractMember implements Member, Borrower {
        public void borrowHolding(int holdingId)
                    throws InsufficientCreditException, MultipleBorrowingException {

            // TODO Auto-generated method stub

                System.out.println("Hello");
    //      Map&lt;Integer, Holding&gt; LibHoldingMap = libCollection.holdingMap;     
    //      holding = (Holding)LibHoldingMap.get((Integer)holdingId);
    //      
    //      if (holding.isOnLoan()) {
    //          System.out.println("Can not be issued Currently on Load");
    //      } else {
    //          System.out.println("Can be issued");
    //      }
        }
    }

    public interface Borrower {
        void borrowHolding(int holdingId)throws InsufficientCreditException, MultipleBorrowingException; 
    }
</code></pre>

<p>when i am calling the borrowHolding i am getting nullPointerException i don't know the method can not be called don't know why.</p>
