Thread: Sorting ArrayList

Hello everyone,


Let me describe my program a bit.


There are 5 classes which describe Person, Tool, Building, Room and Organisation. They all have a String field so they are all similar. So I made an Abstract class which includes the getName method (which returns the name of the class)


The problem starts in this section. I have a class which creates an ArrayList for each and every class like this:

public class Lists implements Comparable<AllObjects> {
	private ArrayList<Person> personList;
	private ArrayList<Device> deviceList;
	private ArrayList<Building> buildingList;
	private ArrayList<Room> roomList;
	private ArrayList<Organisation> orgList;
 
	public Lists () {
		this.personList = new ArrayList<Person>();
		this.deviceList = new ArrayList<Device>();
		this.buildingList = new ArrayList<Building>();
		this.roomList = new ArrayList<Room>();
		this.orgList = new ArrayList<Organisation>();
	}

I needed to implement comparable, because I have to sort these ArrayLists according to their Objects' names.

But it seems that I can't write this comparison in Lists class. So I tried writing this comparable method in the ABSTRACT class of all my objects.

But I just can't get it working. Can someone please give me a hint ?


Here is the Person class:

public class Person extends AllObjects {
	private String name;
 
	public Person (String s) {
		this.name = s;
	}
	public String getName() {
    	return this.name;
    }
}

And the abstract class of all 5 Classes;

public abstract class AllObjects implements Comparable<AllObjects>{
	private String name;
 
 
	public String getName() {
    	return this.name;
    }
 
	public int CompareTo(Object tmp1)
    {
       tmp1 = (AllObjects) tmp1;
       int result = this.getName().compareTo(((AllObjects) tmp1).getName());
 
       return result;
    }
}

Define "But I just can't get it working"...does it compile? Does it not function correctly?

Ok it was my first time sorting an ArrayList and i figured it out,

Seems like it was a basic error.



I was using COMPARATOR instead of COMPARABLE and i found the compareTo method overriding a bit hard to write. (Because its been just a few months since i started java..)


But try-and-learn is the best way possible. Now I figured it all out, but thanks for your concern anyway