• Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 431
  • Last Modified:

Sorting list of objects based on child object members

Here is a simple version of my problem, consider the following 2 classes. Given a list of Car objects, I would like to sort first by Category name, then by Car name. Is there anything in the api that can help with this task? Or what sort algorithm would be best consider the Lists I'm working with would not exceed 1000 entries. Thank you.
public Car {
  public String name;
  public Category cat;
  .....
}
 
public Category {
  public String name;
  ....
}

Open in new window

0
saic_gco
Asked:
saic_gco
  • 2
  • 2
1 Solution
 
objectsCommented:
// by name

Collection.sort(cars, new Comparator()
{
   public int compare(Object a, Object b)
   {
       Car car1 = (Car) a;
       Car car2 = (Car) b;
       return car1.getName().compareTo(car2.getName());
   }
});
System.out.println(cars);

// by category

Collection.sort(cars, new Comparator()
{
   public int compare(Object a, Object b)
   {
       Car car1 = (Car) a;
       Car car2 = (Car) b;
       return car1.getCatgory().getName().compareTo(car2.getCategory().getName());
   }
});
System.out.println(cars);
0
 
objectsCommented:
or to sort by cat, then by name (if cat same) use:

Collection.sort(cars, new Comparator()
{
   public int compare(Object a, Object b)
   {
       Car car1 = (Car) a;
       Car car2 = (Car) b;
       int bycat = car1.getCatgory().getName().compareTo(car2.getCategory().getName());
       return bycat==0 ? car1.getName().compareTo(car2.getName()) : bycat;
   }
});
System.out.println(cars);
0
 
ysnkyCommented:
hey objects,
it not Collection.sort
it is    Collections.sort  :)))
 
0
 
saic_gcoAuthor Commented:
objects.complimentStringVector.add("you da man");
0
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

Join & Write a Comment

Featured Post

Keep up with what's happening at Experts Exchange!

Sign up to receive Decoded, a new monthly digest with product updates, feature release info, continuing education opportunities, and more.

  • 2
  • 2
Tackle projects and never again get stuck behind a technical roadblock.
Join Now