Generic « comparator « Java Collection Q&A

1. How do I implement a Comparator using Generics?    stackoverflow.com

Just a minor problem with Arraylist. I want to sort a ArrayList<Client> by name.

Class Client{ String name; int phonenumber ..}

2. Java Collections.sort - help me remove the unchecked warning    stackoverflow.com

List<Question> questions = new ArrayList<Question>();
questions.addAll(getAllQuestions()); //returns a set of Questions
Collections.sort(questions, new BeanComparator("questionId")); //org.apache.commons.beanutils.BeanComparator

3. Java Class hierarchies with Generics, Comparator and sort error    stackoverflow.com

I've been looking around to see if I find something to help me with my problem, but no luck until now. I've got the following classese:

  public interface ISort<T> {
 ...

4. Java generics: Collections.max() signature and Comparator    stackoverflow.com

I understand the get and put principle for collections: if a method takes in a collection that it will write a type T to, the parameter has to be ...

5. Comparable and Comparator contract with regards to null    stackoverflow.com

Comparable contract specifies that e.compareTo(null) must throw NullPointerException. From the API:

Note that null is not an instance of any class, and e.compareTo(null) should throw a NullPointerException even though ...

6. How come generic type parameter says "extends" Comparable not "implements"?    stackoverflow.com

I tried to write generic function that remove the duplicate elements from array.

public static <E extends Comparable<E>> ArrayList<E> removeDuplicate(E[] arr) {
        //do quicksort
  ...

7. Comparator for Generic Interface Without Warnings    stackoverflow.com

Given:

public interface PrimaryKey<Key extends Comparable> {
    Key getKey();
}

public class PrimaryKeyComparator implements Comparator<PrimaryKey> {
    public int compare(PrimaryKey first, PrimaryKey second) {
      ...

8. comparator java     stackoverflow.com

My question is the following, I have an interface that requires me to return java.util.Comparator <E>, my question is, how can i implement an abstract class that somehow returns a generic Comparator. ...

9. Sorting generics in Java    stackoverflow.com

I have to implement a generic AVL tree as homework. It's defined as follows:

public class AVL<Key,Elem>;

10. Generic Comparator    stackoverflow.com

This is for a school project. I have a Query class that holds an element that is part of the Query condition. So if it's a GreaterQuery and the ...

11. Generics and Comparator best practices    coderanch.com

Should Foo be written like version 1 or version 2 below? What are the considerations for choosing between the two? Are there any upsides or downsides for one or the other? class Foo implements Comparator{ ... public int compare(Object o1, Object o2) { ... } } class Foo implements Comparator{ ... public int compare(Foo foo1, Foo foo2) { ... } } ...

12. comparator singleton for class of generic parameter    forums.oracle.com

pifpafpuf wrote: Obviously one instance of the comparator per class J would in principle suffice. That's not a reason to use a singleton. There's virtually never a reason to use one, in fact, but in particular only needing a single instance isn't a reason. You'll only need a single instance of a lot of classes. For it to be a candidate ...