kel dobson

Hi Guys
Problem is a java program in BlueJ, which needs to store names and ages in an arraylist for members of a "computer games club" for my college project. A second arraylist holds a list of computer games
I want to stop members "enrolling" using the same name - eg 'Fred and Fred = no' 'Fred and Freda = ok'
Classes: Member and Club. Member holds instances of members and Club is an arraylist for members
With help from others at JavaRanch I have got this side of the project running. Part of my problem (apart from being stupid!) is getting communication between two different object / classes, and to some extent
this seems compounded by BlueJ which doesn't always do what I think it should ??
I was trying to use similar syntax to a system.out.println call to return the 'anme' field from objects in the arraylist to compare with each new object in the constructor of Member.
I have been trying a method call to Club which I have called 'public void nameFromArrayList()' but the code is getting messy and I have commented out some lines I have tried just to keep it compiling and running. Anyway apologies for my code - it seems over long compared with the examples I read on these forum pages.
tia kel
/** * Class Member represents members in the GamesClub Project * * @author kel * @version v1.0 */ public class Member { // instance variables private String name; // members name private String memberNo; // membership number private int age; // age - see Game Class - ? store as an int or string ? private Club club; private Club members; /** * Constructor for objects of class Member */ public Member(String name, int age, String memberNo) { // if ( 1 == 1 ) // ( equalsIgnoreCase this.name club.nameFromArraylist() ) { System.out.println("we have a member using that name"); // System.out.println(this.name); // System.out.println(members.nameFromArraylist()); } // else { this.name = name; this.age = age; this.memberNo = memberNo; System.out.println(this.name); } } public void arrayName() //testing a method call to Club { members.listAllMembers(); } /** * Three methods to Return the member's: name, number and age * * @return name * @return memberNo * @return age */ public String getName() { return name; // gets name } public String getNumber() { return memberNo; // gets membership number } public int getAge() { return age; // gets 'age' - still not sure if to store as int or string?? } /** * Returns a String representation of a Member object * * @return a String object of class Member */ public String toString() { return ( name + " " + age + " " + memberNo); } public String toString(String name) { return ( name ); } } /** * Class Club holds an arraylist of Members. * * @author kel * @version v1.0 21/12/2003 */ import java.util.*; public class Club { private ArrayList members; // collates members into a collection - an ArrayList private Member member; // links to objects in Member Class /** * Constructor for objects of class Club to hold a set of members */ public Club() { members = new ArrayList(); // create new arraylist called "members" } /** * A method to add member(s) to the arraylist * * @param a member object - the member to be added */ public void addMember(Member member) { members.add(member); } /** code trying to find a loop testing new name against other names * * */ /** * Adds a pre-listed group of "members" to the Club ArrayList * * parameters not listed */ public void enrolListOfMembers() { addMember( new Member ("Fred", 21, "D30") ); addMember( new Member ("Freda", 19, "A31") ); addMember( new Member ("Frederick", 16, "K32") ); addMember( new Member ("Frederica", 13, "A33") ); } /** * An example of a method - replace this comment with your own * * @return the number of members stored in this ArrayList */ public int numberOfMembers() { // System.out.println(members.size() ); return members.size(); } /** * Shows members details to terminal window * * @param listPosition - arraylist position of member */ public void showMember(int listPosition) { String exhibitMember; if ( listPosition < numberOfMembers() ) { exhibitMember = members.get(listPosition).toString(); System.out.println(exhibitMember); } } /** Method to list all members * * @param numberShown - an index number for trawling the arraylist dec as local var */ public void listAllMembers() { System.out.println("Name / Age / Membership Number"); System.out.println("======================"); int numberShown = 0; while ( numberShown != numberOfMembers() ) { showMember (numberShown); numberShown ++; } System.out.println(); } /** Method to check new member has unique name * * @param numberShown - an index number for trawling the arraylist dec as local var */ public void nameFromArrayList() { int index = 0; String membersName; while ( index != numberOfMembers() ) { membersName = members.get(index).toString(); index ++; } } }
[ December 23, 2003: Message edited by: kel dobson ]

hi
Is it OK to continue on this theme please?
sorry, but I don't understand what you mean by " . . . member does expose"??

I have trouble in BlueJ with anything other then a very simple test to an 'if' statement.
Can I compare a new input string with equalsIgnoreCase with a name recovered from an ArrayList object by using toString() and passing the 'name' variable back to the constructor of the first class to prevent two similar names being input?

Hi
Thanks for your speedy and helpful response. Thought I understood this object reference stuff but I am still confused.
Hope you don't mind but I will include my code - hope I can get the hang of the code section here!?
A further class instantiates instances of "Members" but I have populated the ArrayList with 4 examples for testing.
Similar code runs in a different project without trouble and I thought I had carefully transposed the variables and object references to the new class - but it returns the 'Class and Hash code' as you mention.
I am even more confused as the 'get method' - "numberOfMembers" correctly returns the int '4' so I think I am pointing the code to the correect class etc?
Here's hoping you can point me in the right direction?
/** * Class Club holds an arraylist of Members. */ import java.util.*; public class Club { private ArrayList members; // collates members into a collection - an ArrayList /** * Constructor for objects of class Club to hold a set of members */ public Club() { members = new ArrayList(); // create new arraylist called "members" } /** * A method to add members to the arraylist * * @param a member object - the member to be added */ public void addMember(Member member) { members.add(member); } /** * Adds a pre-listed group of "members" to the Club ArrayList */ public void enrolMembers() { addMember( new Member ("Fred", 21, "D30") ); addMember( new Member ("Freda", 19, "A31") ); addMember( new Member ("Frederick", 16, "K32") ); addMember( new Member ("Frederica", 13, "A33") ); } /** * An example of a method - replace this comment with your own * * @return the number of members stored in this ArrayList */ public int numberOfMembers() { System.out.println(members.size() ); return members.size(); } /** * Shows members details to terminal window * * @param listPosition - arraylist position of member */ public void showMember(int listPosition) { String exhibitMember; if ( listPosition < numberOfMembers() ) { exhibitMember = members.get(listPosition).toString(); System.out.println(exhibitMember); } }
[ December 20, 2003: Message edited by: kel dobson ]

Hi
trying to get output to screen terminal from an arraylist of objects using system.out.print(ln)
the terminal window prints out the membory reference used, either by java (or BlueJ), but not the fields of the object I want to retrieve
apologies for my ignorance but any advice greatly appreciated
as you will all quickly guess - I am very new to Java!!