Sort a Vector of custom objects

I'm trying to sort a Vector in java but my Vector is not a vector of int, it is a vector of objects

the object is:

public MyObject() {
    numObj = 0;
    price = new Price();
    pax = new Pax();        
}

so I have a Vector of MyObject and I want to order it by numObject, how do i do it, 开发者_JS百科I'm new in java?

Thank you so much for all your help.

I assume you are using Collections.sort(..). You have two options:

• make your class implement Comparable
• when sorting, create a custom Comparator

An example for implementing Comparable would be:

public class MyObject implements Comparable<MyObject> {
   // ..... other fields and methods
   public int compareTo(MyObject other) {
        return numObj - other.getNumObj();
   } 
}

This will mean the items are sorted in ascending order. If you want other, custom sorting, you can create a Comparator that defines the custom comparison and pass it as an argument to Collections.sort(..);

To sort a vector of object, first the class MyObject must implement Comparable and implement method compareTo(Object), then use Collections.sort(Vector)

class MyObject implements Comparable<MyObject> {
    public int compareTo(MyObject a) {
       //return either 1, 0, or -1
       //that you compare between this object and object a
  ``}
}

//and in your logic write this line
Collections.sort(myVector);

check the JavaDoc of Vector

Implementing Comparable will work fine. However, it should be done with caution in order to prevent future bugs. The implementations above are great for sorting, but if you later decide to put your MyObject instances into a SortedSet (such as TreeSet), you will have an unexpected behavior. Items which are not identical will collide with each other if they have the same value of the numObject data member. This happens because sorted sets use the Comparable implementation (by default) in order to determine equality.

See http://eyalsch.wordpress.com/2009/11/23/comparators/ for details.