comparable

what I would like to achieve is to sort a colletion of objects by a string value. However in a locale dependant way using a collator. Due to performance reasons I do not want to use the Collator compare() method (as below in the code) rather the CollationKey class, as the java API states the using a CollationKey is much faster. But how do I implement the compareTo() method using the CollationKey? As far as I understood it, I have to completely write all the comparison Methods on my own if I will be using a CollationKey. So I will even no longer be able to use the Collections.sort() methods...

Option 1: Make a list which implements Comparable and sort it using collections.sort(List l) every time you add a value. Option 2: Make a TreeSet (which keeps itself sorted all the time). Which one will be faster? I am asking this because List gives me the option of ListIterator which I need in my case, since it lets me add an element while iterating. The most important differences: Criterion | List with Collections.sort | TreeSet ----------------+----------------------------+--------- cost of adding | O(n log n) | O(log n) equal sort keys | permitted | eliminated as duplicates iteration |

This is from the Stream interface from Oracle's implementation of JDK 8: public interface Stream<T> extends BaseStream<T, Stream<T>> { Stream<T> sorted(); } and it is very easy to blow this up at run time and no warning will be generated at compile time. Here is an example: class Foo { public static void main(String[] args) { Arrays.asList(new Foo(), new Foo()).stream().sorted().forEach(f -> {}); } } which will compile just fine but will throw an exception at run time: Exception in thread "main" java.lang.ClassCastException: Foo cannot be cast to java.lang.Comparable What could be the reason

本文，先介绍 Comparable 和 Comparator 两个接口，以及它们的差异；接着，通过示例，对它们的使用方法进行说明。 Comparable 简介 Comparable 是排序接口。 若一个类实现了Comparable接口，就意味着“ 该类支持排序 ”。 即然实现Comparable接口的类支持排序，假设现在存在“实现Comparable接口的类的对象的List列表(或数组)”，则该List列表(或数组)可以通过 Collections.sort（或 Arrays.sort）进行排序。 此外，“实现Comparable接口的类的对象”可以用作“有序映射(如TreeMap)”中的键或“有序集合(TreeSet)”中的元素，而不需要指定比较器。 Comparable 定义 Comparable 接口仅仅只包括一个函数，它的定义如下： package java.lang; import java.util.*; public interface Comparable<T> { public int compareTo(T o); } 说明： 假设我们通过 x.compareTo(y) 来“比较x和y的大小”。若返回“负数”，意味着“x比y小”；返回“零”，意味着“x等于y”；返回“正数”，意味着“x大于y”。 Comparator 简介 Comparator 是比较器接口。

I am trying to implement a sorted and unsorted array list. Both extend a class called AbstractArrayMyList which contains common operations/implementations - toString, clear, etc.... Here is my code for AbstractArrayMyList(which implements a generic interface I defined) public abstract class AbstractArrayMyList<E> implements MyList<E> { protected E[] elementData; ..... } I chose to make elementData protected so that sorted and unsorted specialized array lists can access and perform operations on it. Here is my declaration/code for sorted array list public class ArrayListSorted<E extends

A.java public class A implements Comparable { private String id; private String name; public A(String a, String b) { id = a; name = b; } public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int compareTo(Object o) { A a = (A) o; return id.compareTo(a.getId()); } } B.java public class B implements Comparable { private String b_id; private String other; public B(String a, String b) { b_id = a; other = b; } public String getBId() { return b_id; } public void setBId