hi there, I am stuck at somewhere same. /* ISPN.java * A class to represent an imaginary "International Standard Program Number" */ package tma01q1; public class ISPN { private int[] authorId; private int[] programId; /** * Creates a new instance of ISPN */ public ISPN(int[] anAuthorId, int[] aProgramId) { authorId = anAuthorId[] ; programId = aProgramId[] ; } public boolean isValidLength() { if ((authorId.length + programId.length) == 6) return true; } public boolean isAllValidDigits() { // TODO return false; } public String getAuthorIdAsString() { // TODO return null; } public String getProgramIdAsString() { // TODO return null; } public int calculateCheckDigit() { // TODO return 0; } public String toString() { // TODO return null; } public boolean equals(ISPN ispn) { // TODO return false; } }