Beginner Problems

[Grant_Searle]

Hello java-forums,
I'm new here and new to the language.
I am trying to create a program as a side project to my studies but am having some difficulties.

I would like to create a simple record system that holds information like:

• Name
• Date of Birth
• Address
• etc

In this 'system' I would like to be able to add new 'records' and edit or delete them once created.
From reading various online tutorials, I know this will require an array or two for my 'objects' and a fair few if statements and methods but I have no idea how to expand on the program I have already, which is this:

import java.util.*;

public class UserInput {
    public static void main(String[] args) {
        List<String> list = new ArrayList<String>();
        Scanner stdin = new Scanner(System.in);

        do {
            System.out.println("Current list of Students is: " + list);
            System.out.println("Add more? (y/n)");
            if (stdin.next().startsWith("y")) {
                System.out.println("Enter New Details: ");
                list.add(stdin.next());
            } else {
                break;
            }
        } while (true);

        System.out.println("Student Information is now: " + list);
        String[] arr = list.toArray(new String[0]);
        System.out.println("Array is " + Arrays.toString(arr));
    }
}

At the moment my program simply prints the first string I enter, but I'd like something more advanced,
I was thinking about adding something like this:
Person[] kid = new Person[];
kid[0] = new Person("Grant Searle", "09/12/1991", "Address..." );
kid[1] = new Person("John Doe", "etc");
kid[2] = new Person("Tony Tester", "etc");

Therefore there would be data in the program already but a 'user' could always add or edit more.

If any one could point me in the right direction that would be much appreciated.

Thank you

[JosAH]

As you already wrote yourself: design and implement a Person class that store a name, dob, address etc. per person. For now implement a constructor that takes those String values as parameters. For additional functionality you can make your Person class implement the Comparable<Person> interface so you can store Person objects in a SortedSet or sort a List of Persons; make sure you also implement the equals( ... ) method as well as the hashCode() method. The API documentation will tell you all about the details.

kind regards,

Jos

[kevinn205]

Is your problem how it only displays one result yet you want it to display all? if so try making a loop statment to retrieve all the data and break down the arrray list into colummns such as name age time etc

[Grant_Searle]

Hi again, thank you both for your replies.
I've been playing with the code for a few days now, i know WHAT i want to do and the WAY in which it is done
but... i dont know HOW to go about writing it

I've kinda been writing what bits i know of the code and as a result there is holes everywhere and i get errors.

I now have 2 files:

class Student {
  private String name;
  private String DoB;
  private String term;
  private String home;
  private String course;
  private int fees;
  private String rela;
  private int marks;
  private String prog;

public Student(String n, String d, String t, String h, String c, int f, String cr, int m, String p) {
name = n;
DoB = d;
term = t;
home = h;
course = c;
fees = f;
rela = cr;
marks = m;
prog = p;

  }

  public String print() {
    return name + "\n" + DoB + "\n" + term + "\n" + home + "\n" + course + "\n" + fees + "\n" + rela + "\n" + marks + "\n" + prog;
  }

 public String toString() {
 return "These are the Current Stored Details:\n" + print();
}
}

and the second is the one i'm having problems with

public class StudentTest 
{
  public static void main(String[] args) 
{
String n;
String d; 
String t; 
String h;
String c;
int f; 
String cr;
int m; 
String p;

    Student[] kid;
    kid = new Student[1];
    int i = 0;

   n = "Grant Searle";
   d = "09/12/1991";
   t = "Same as Home Address";
   h = "5 James Road, Gosport, Hampshire, PO13 0TF";
   c = "Computer Network Management & Design";
   f = 3275;
   cr = "Mother";
   m = 56;
   p = "Yes";

   Student startingKid = new Student( n, d, t, h, c, f, cr, m, p ) ;
   kid[i] = startingKid;


for (i = 0; i < kid.length; i++)
System.out.println(kid[i]);


KeyboardInput in = new KeyboardInput() ;

String inName; String inDate; String inTerm; String inHome; String inCourse; int inFees; String inRela; int inMarks; String inProg;

inName = n;
inDate = d;
inTerm = t;
inHome = h;
inCourse = c;
inFees = f;
inRela = cr;
inMarks = m;
inProg = p;

 kid[1] = new Student (n, d, t, h, c, f, cr, m, p);


do {
   System.out.println("What do you want to do?");
   System.out.println("1) Add a Student Record");
   System.out.println("2) Edit a Student Record");
   System.out.println("3) Quit");

   String answer = in.readString();

   if(answer.equals("1") ){

System.out.println("Please Enter Student's Full Name:");
String inName = in.readString() ;

System.out.println("Please Enter Student's Date of Birth:");
String inDate = in.readString() ;

System.out.println("Please Enter Student's Term Address:");
String inTerm = in.readString() ;

System.out.println("Please Enter Student's Home Address:");
String inHome = in.readString() ;

System.out.println("Please Enter Student's Course Name:");
String inCourse = in.readString() ;

System.out.println("Please Enter Student's Course Fees, £:");
double inFees = in.readDouble() ;

System.out.println("Please Enter Student's Closest Relative:");
String inRela = in.readString() ;

System.out.println("Please Enter Student's Marks:");
int inMarks = in.readInteger() ;

System.out.println("Please Enter Student's Progression: (yes/no)");
String inProg = in.readString() ;
  
   }
   else if(answer.equals("2") )
{
      System.out.println("What is the Student's ID?");
     //here i'd like some kind of index system so the user can type student 1 and that would edit array [0] by overwriting the 'stored' information
     // int studentNumber = Integer.parseInt(in.readString());
     // for(int y=0; y < newEntry; y++)
     // {
     //   if(studentNum[y] == studentNumber)
          //found the student
          //do the adding of new details, submit and overwrite
     //}
   }
   while(!answer.equals("3"));
{
// later add a delete option, ie. move current array into temp smaller array to shift elements instead of making null
}

  }
}
}

I know i've made mistakes and my syntax is probably horrid but if anyone could help me out i'd really appreciate it.

Thanks

[Grant_Searle]

also noticed i have declared inName etc twice :/

[CHLim]

Hi Grant,

I can see a few problems in your code.


First, im guessing that you've created the Student[] to store more than 1 student. By saying " kid = new Student[1];" at line 16 you have created a Student[] that can take only 1 Student object. And at line 51 you have created a second Student object for a Student[] that can only take 1 element. This would cause an error because you cannot grow an array like this. If you want to store the student object i would recommend looking into either the ArrayList class or the HashMap class.

Second, at line 34 you have said "System.out.println(kid[i]);". When you do this what you are printing is a memory address for the Student object at kid[i]. Try converting it to a string first.

GoodLuck

[Grant_Searle]

Hey again, I've been playing some more and made my code much tidier and it compiles now.

here is what i've changed it to:

public class StudentTest 
{
  public static void main(String[] args) 
{
String n;
String d; 
String t; 
String h;
String c;
int f; 
String cr;
int m; 
String p;

    Student[] kid;
    kid = new Student[5];
    int i = 0;

   n = "Grant Searle";
   d = "09/12/1991";
   t = "Same as Home Address";
   h = "5 James Road, Gosport, Hampshire, PO13 0TF";
   c = "Computer Network Management & Design";
   f = 3275;
   cr = "Mother";
   m = 56;
   p = "Yes";

   Student startingKid = new Student( n, d, t, h, c, f, cr, m, p ) ;
   kid[i] = startingKid;


System.out.println("What would you like to do?");
System.out.println("1) Add a student record");
System.out.println("2) Edit an existing record");
System.out.println("3) Delete a student record");
System.out.println("4) Display current records");


KeyboardInput in = new KeyboardInput() ;
int x = in.readInteger() ;

if (x == 1)

System.out.println("Please Enter Student's Full Name:");


else if (x==2)
System.out.println("Edit");

else if (x==3)
System.out.println("Delete");

else if (x==4)
for (i = 0; i < kid.length; i++)
System.out.println(kid[i] + "\n");

else
System.out.println("do nothing");	
	
  }
}

Now my question is, how in if x==1 do i save user input to the kid array,
I've tried:
System.out.println("Please Enter Student's Full Name:");
String inputName = in.readString() ;

However the error i get is else without if, I've tried removing certain ; but same error.
How can it work without String inputName = in.readString() ; but not with?