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Join Date: Feb 2008
Posts: 39
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Light Poster
Primary Key pls help! I am trying to do a primary key so that each member can't hava the same ID and if th same ID is entered an error is give. Can someone please help me cause I can't do it at all.Thank you.
static void addMember(ArrayList<GymUser> UserListIn)
{
String tempUserrID;
String tempID;
String tempName;
String tempSurname;
int tempAge;
String tempAddress;
int tempPhone;
String tempDuration;
Scanner keyboard = new Scanner(System.in);
keyboard.useDelimiter("\n");
System.out.println("Please enter the member's Personal Details");
System.out.println("-------------------- ");
System.out.println("Enter the mebership number");
tempUserrID = keyboard.next();
System.out.print("Enter the ID no.: ");
tempID = keyboard.next();
System.out.print("Enter Name: ");
tempName = keyboard.next();
System.out.print("Enter Surname:");
tempSurname = keyboard.next();
System.out.print("Enter Address:");
tempAddress = keyboard.next();
System.out.print("Enter Age:");
tempAge = keyboard.nextInt();
System.out.print("Enter Phone:");
tempPhone = keyboard.nextInt();
System.out.print("MemberShip Duration:");
tempDuration = keyboard.next();
UserListIn.add(new GymUser(tempUserrID, tempName, tempID, tempSurname, tempAddress, tempPhone, tempAge,tempDuration));
}
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Join Date: Dec 2007
Location: Greece
Posts: 537
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Rep Power: 3
Solved Threads: 57
Posting Pro
Inside the: UserListIn.add(GymUser newGymUser) method you will take the new Gym User and compare him with the other gymUsers. If one with the same id already exists then don't add him and print a message or throw an Exception.
If you don't want to make this check inside the .add method, then before calling it, take all the other users and compare them with the new user. If the new user doesn't have the same id, then call your method.
By the way, if you are using a database, and the table already is created with a primary key then you don't need to check anything because an SQLException will be thrown and the new user won't be inserted
If you don't want to make this check inside the .add method, then before calling it, take all the other users and compare them with the new user. If the new user doesn't have the same id, then call your method.
By the way, if you are using a database, and the table already is created with a primary key then you don't need to check anything because an SQLException will be thrown and the new user won't be inserted
I AM the 12th CYLON
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Join Date: Feb 2008
Posts: 39
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Light Poster
No for this database I am using java. I know database are generally coded with SQL but in my assigment I need to use java. Can you help me a bit in the coding and where to put it because I'm still a beginner with this type of coding. Thank you very much javaAddict.
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Join Date: Mar 2004
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Master Poster
I suppose you could just use a HashMap
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Join Date: Dec 2007
Location: Greece
Posts: 537
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Posting Pro
I already told you where to put it. Just create a method that returns boolean and has a GymUser argument, that checks whether the input gymUser's id already exists among the other users that are already stored. By the way, where do you store the other users?(ArrayList, Vector?)
GymUser newGymUser = new GymUser(tempUserrID, tempName, tempID, tempSurname, tempAddress, tempPhone, tempAge,tempDuration);
boolean b = alreadyExists(newGymUser );
if (b) {
System.out.println("Cannot insert existing user");
} else {
UserListIn.add(newGymUser );
} I AM the 12th CYLON
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Join Date: Feb 2008
Posts: 39
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Light Poster
I don't know how to use hash maps. I'm that good in java. All I want to do I think is to compare the allready saved ID no to the new ID being inputted. But I'don't know how to code the thing and where to place it.
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Join Date: Feb 2008
Posts: 39
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Light Poster
In an array List.
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Join Date: Feb 2008
Posts: 39
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Rep Power: 1
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Light Poster
I've done this till now from the help given form you both. But now if I will have an error (cannot find symbol - variable newGymUser). I am storing these users in an array list. Thank you very much javaAddict....but I'm still having errors.Can oyu help me pls. Thanks
static void addMember(ArrayList<GymUser> UserListIn)
{
String tempUserrID;
String tempID;
String tempName;
String tempSurname;
int tempAge;
String tempAddress;
int tempPhone;
String tempDuration;
Scanner keyboard = new Scanner(System.in);
keyboard.useDelimiter("\n");
System.out.println("Please enter the member's Personal Details");
System.out.println("-------------------- ");
System.out.println("Enter the mebership number");
tempUserrID = keyboard.next();
System.out.print("Enter the ID no.: ");
tempID = keyboard.next();
System.out.print("Enter Name: ");
tempName = keyboard.next();
System.out.print("Enter Surname:");
tempSurname = keyboard.next();
System.out.print("Enter Address:");
tempAddress = keyboard.next();
System.out.print("Enter Age:");
tempAge = keyboard.nextInt();
System.out.print("Enter Phone:");
tempPhone = keyboard.nextInt();
System.out.print("MemberShip Duration:");
tempDuration = keyboard.next();
UserListIn.add(new GymUser(tempUserrID, tempName, tempID, tempSurname, tempAddress, tempPhone, tempAge,tempDuration));
boolean b = alreadyExists(newGymUser ); /error here
if (b) {
System.out.println("Cannot insert existing user");
} else
{
UserListIn.add(newGymUser );
}
GymUser newGymUser = new GymUser(tempUserrID, tempName, tempID, tempSurname, tempAddress, tempPhone, tempAge,tempDuration);
boolean b = alreadyExists(newGymUser );
if (b) {
System.out.println("Cannot insert existing user");
} else
{
UserListIn.add(newGymUser );
}
} •
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Join Date: Dec 2007
Location: Greece
Posts: 537
Reputation:
Rep Power: 3
Solved Threads: 57
Posting Pro
You will have an ArrayList. (Read the API) Before you do an add, you will read all the existing users and compare their IDs with the new one. If it does not exist then inserted.
http://java.sun.com/j2se/1.5.0/docs/...w-summary.html
Try the util package
http://java.sun.com/j2se/1.5.0/docs/...w-summary.html
Try the util package
I AM the 12th CYLON
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