Thread: Array object and constructors

Hi all,
I wish to create an array object which can collect three string values…..
Collecting them from keyboard entry and then reprint them in output one by one……
I am able to collect for one time for an object and constructor
But if I convert the object to array the constructor cannot recognizes it……
How can I do the same……
Please help……

Regards,
Tarun

This is how you make a ArrayList

ArrayList alist = new ArrayList(3);
alist.add("something");
alist.add("something2");
alist.add("something3");

I dont quite understand you question.

I am able to collect for one time for an object and constructor
But if I convert the object to array the constructor cannot recognizes it……

What?

Thanx bryn for reply..
But I think my question is not clear………..
I am giving you some more detail…..
My constructor

// class staff
class staff
{
	String Code,Name;
	staff(String a, String b)
	{
		String Code= a;
		String Name= b;
	}
}
 
//subclass officer extends staff
class officer extends staff
{
	String Grade;
 
	officer (String a, String b,String c)
	{
		super (a,b);
		Grade=c;
	}
	String showData()
	{
		String n=Code+Name+Grade;
		System.out.println(n);
		return (n);
	}
}

//main class I removed other subclasses for clearance
import java.io.*;
class employee
{
public static void main(String [] Tarun)
throws IOException
{
	System.out.print("Welcome to SAGA \nGive the details for new entry:\nJob Code:\nA)Officer \tB)Teacher\tC)Typist\n");
	BufferedReader Job= new BufferedReader (new InputStreamReader (System.in));
	String Code=Job.readLine();
	System.out.print("Name:");
	BufferedReader Nm=new BufferedReader (new InputStreamReader(System.in));
	String Name=Nm.readLine();
	if (Code.equals("Officer"))
	{
 
		System.out.print(Code+Name+"Please Enter Grade:");
		BufferedReader Gr=new BufferedReader (new InputStreamReader (System.in));
		String Grade=Gr.readLine();
		System.out.println(Code+Name+Grade); //just checking that all input are correct.
		officer O=new officer(Code,Name,Grade);
		String show=O.showData(); 
	}
}

Now if I wish to maintain the input such that each time I enter new officer detail and ask for reprint it should give all the entries for Officer……..

I hope I have made it a bit clear…..
Do reply……

Regards,
Tarun

Plz help me...........

String n=Code+Name+Grade;

This is no good.
You need to understand inheritance. Code and name are need to be called like: super.code, super.name and grade can be called like this.grade.

Dear brayn,
Thanx for replying again but the problem is not with the variables my code runs with that (String n=Code + Name + Grade .
As per my knowledge, the use of super.code or super.name will be needed if I use the same variables in sub class.
I am having problem with how to define an array which can hold the officer object as its variable….
For example if I define Of1, Of2, Of3…..as officer object. I wish to store them in a array object of offi type such that
Offi [0] = Of1;
Offi [2] = Of2;
Offi [3] = Of3;
One more condition is that i can put n no. of input to the Offi array object.
hop to see you reply back soon

Regards,
Tarun

ArrayList<Officer> officerlist = new ArrayList<Officer>();

As long you keep the constructor empty, the ArrayList will have no limit of amount of objects it can hold.

Is this what you need?

BTW if you use a hashtable you can set your own key to the hashtable.
Example:

Hashtable<Officer> officerlist = new Hashtable<Officer>();
officerlist.put(officer.getId(), officer); //officer id as key and officer object as value
Officer someofficer = (Officer)officerlist.get(officer.getId()); //will retrieve the officer object

Difference between ArrayList and Hashtable is that you can determine your own keys wich also can be strings.

thanx bryan,
I am able to creat the Array list......but i think i am not using it in the right way....
I have defined as below steps to my previous code but i am not able to get the values back...
can you please resolve...

ArrayList<officer> officerlist = new ArrayList<officer>();
officerlist.add(0,O);
System.out.println(officerlist); // gives me the memory loacation not the contents as expected

seeking your support

regards
Tarun

Originally Posted by Bryan

As long you keep the constructor empty, the ArrayList will have no limit of amount of objects it can hold.

Not exactly. The constructor argument specifies the initial capacity - you can still add as many more items as will fit in memory. Use the initial capacity to improve efficiency when you know roughly how many items you will be using.

Originally Posted by dlorde

Not exactly. The constructor argument specifies the initial capacity - you can still add as many more items as will fit in memory. Use the initial capacity to improve efficiency when you know roughly how many items you will be using.

Ahh, didn't knew that I though you would have to make the capacity bigger manual, like calling a method.

It's all documented in the ArrayList API docs...

I know but I didn't really had the chance yet to explore ArrayLists. I just know the base I rather use hashtables

Originally Posted by Bryan

I know but I didn't really had the chance yet to explore ArrayLists. I just know the base I rather use hashtables

Thing is, ArrayLists and Hashtables are for quite different uses. ArrayLists are just easy-to-use dynamic arrays, whereas Hashtables are keyed collections for mapping values onto unique keys...

I recommend a browse through the Collections Tutorial to get the basics sorted - it doesn't take long, and it pays off big time

Originally Posted by dlorde

Thing is, ArrayLists and Hashtables are for quite different uses. ArrayLists are just easy-to-use dynamic arrays, whereas Hashtables are keyed collections for mapping values onto unique keys...

I recommend a browse through the Collections Tutorial to get the basics sorted - it doesn't take long, and it pays off big time

Great, thats what I need often, also for my current project. When I put objects in the hashtable I want to sign my own key to it, which often will be objectId() or something similar. Thanks for the link though.