Programming Forums - View Single Post - about sort()-method

Arevos · Nov 25th, 2005, 2:22 PM

You need a custom Comparator to tell Java how to sort. Comparator objects have a "compare" method that takes two Objects as arguments and returns an integer. If the integer is negative, the first object is less than the second; if the integer is positive, the first object is greater than the second; if the integer is 0, the objects are equal. The String.compareTo method can compare two strings in this way.

You can use an anonymous class to save cluttering up your code with a class that will only be used once. Maybe something like:

(Toggle Plain Text)

Collections.sort(cInd, new Comparator() {
   int compare(Person a, Person b) {
      return a.getLastName().compareTo(b.getLastName());
   }
});

Nov 25th, 2005, 2:22 PM	#2
Arevos Programming Guru Join Date: Aug 2005 Location: England Posts: 1,499 Rep Power: 5	You need a custom Comparator to tell Java how to sort. Comparator objects have a "compare" method that takes two Objects as arguments and returns an integer. If the integer is negative, the first object is less than the second; if the integer is positive, the first object is greater than the second; if the integer is 0, the objects are equal. The String.compareTo method can compare two strings in this way. You can use an anonymous class to save cluttering up your code with a class that will only be used once. Maybe something like: (Toggle Plain Text) Collections.sort(cInd, new Comparator() { int compare(Person a, Person b) { return a.getLastName().compareTo(b.getLastName()); } }); Collections.sort(cInd, new Comparator() { int compare(Person a, Person b) { return a.getLastName().compareTo(b.getLastName()); } });