How to sort elements in an ArrayList of Strings?

Question

 PhoneBookCollection phoneBook = new PhoneBookCollection();

I have an ArrayList of PhoneBook objects. (The getCollection method returns the list)

ArrayList<PhoneBook> list = phoneBook.getCollection();

I then iterate through my ArrayList and get the PhoneBook at the i'th index and get its corresponding Telephone .

for(int i = 0; i < list.size(); i++ ){

String phone = phoneBook.getPhoneBook(i).getTelephone();

}

What I want to be able to do now is sort the getTelephone objects in ascending order. I know that ArrayLists don't have a sort method so i'm having a bit of trouble doing this.

Answer 1

You can create a class that implements Comparator :

public class CustomComparator implements Comparator<PhoneBook> { // Replace PhoneBook with the appropriate
    @Override
    public int compare(PhoneBook t1, PhoneBook t2) {
        return t1.getNumber().compareTo(t2.getNumber()); // Here compare the telephone numbers
    }
}

Then do this:

Collections.sort(list, new CustomComparator());

Answer 2

You can use the java.util.Collections class to sort the lists. Use Collections.sort().

Answer 3

您可以使用java.util.Collections 。

Answer 4

The best will be use standart way with java.util.Collections

String class has method compareTo() and will be sorted automtically:

Collections.sort(nameOfList)