Adding an object to an array of objects

Question

I'm trying to add a new Entry object to an array of objects. I don't know how I would go about writing a method to do this. Also I'd like to increase the size of the array as new elements are added to it.

public class Entry {

    private String surname, initial, extension;

    public Entry() { }

    public Entry(String surname, String initial, String extention) {
        this.surname = surname;
        this.initial = initial;
        this.extension = extention;
    }
}

I want to write the method to add the elemets to the array here. The new Entry object is currently hard coded but this will obviously be altered.

public class ArrayDirectory implements Directory {

    Entry[] entries = new Entry[4];


    public void addEntry(Entry newEntry) {
        newEntry = new Entry("isajas","ssds", "sasdas");

    }
}

Thank you for taking the time to read my question!

Have you considered using an ArrayList<Entry> rather than rolling your own dynamic array? — Tyler Gaona
– Tyler Gaona, Commented Apr 12, 2014 at 20:48

user3507600 · Accepted Answer · 2014-04-12 20:57:34Z

1

Here's how you do exactly what you're asking:

public class ArrayDirectory implements Directory {
    Entry[] entries = new Entry[1];

    public void addEntry(Entry newEntry) {
        Entry[] temp = new Entry[entries.length + 1];
        for (int i = 0; i < entries.length; i++) {
            temp[i] = entries[i];
        }
        newEntry = new Entry("isajas","ssds", "sasdas");
        temp[temp.length - 1] = newEntry;
        entries = temp;
      }
}

But as many suggested, ArrayList (or even Vector) would be a better choice than trying to reinvent the wheel here.

answered Apr 12, 2014 at 20:57

user3507600

1,0759 silver badges15 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

s.d · Accepted Answer · 2014-04-12 20:58:09Z

1

Consider using java.util.ArrayList instead. It is a "resizable-array implementation of the List interface" and provides an easy-to-use API for adding objects, e.g. ArrayList<Type>().add(Object o). Have a look at the Javadoc link above, it's really handy and I use it a lot.

It also saves you the extra work of assigning temporary arrays to-and-fro and creating extra objects...

answered Apr 12, 2014 at 20:58

s.d

4,1856 gold badges38 silver badges69 bronze badges

Comments

Sachin Jain · Accepted Answer · 2014-04-12 20:49:49Z

0

You can maintain a variable which tells you the number of Entries present in the directory. Every time you add/remove an entry just update this variable. Effectively you are implementing a Stack.

public class ArrayDirectory implements Directory {

  Entry[] entries = new Entry[4];
  private int numEntries = 0;

  public void addEntry(Entry newEntry) {
    if (numEntries == 4) { /* Display an error */ }

    newEntry = new Entry("isajas","ssds", "sasdas");
    entries[numEntries] = newEntry;
    numEntries++;
  }
}

Or alternatively you can java's inbuilt ArrayList data structure to add/remove entries.

answered Apr 12, 2014 at 20:49

Sachin Jain

21.9k34 gold badges113 silver badges177 bronze badges

Collectives™ on Stack Overflow

Adding an object to an array of objects

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related