How to use Collections.sort () in java? [on hold]
I have the simple class - Person.
}
I cread the list of person range from 10 to 20 years old.
Now, I would like to sort the list using Collections.sort() method, but I don't understand how this works.
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Your Comparator is wrong. Try this:
or
Think about the contract for Comparator. It returns an int, not boolean.
Generally in your @Override implementation of the compare() function, you will want something that returns -1, 0, or 1 (generally an int). So, in this case you would want something like this:
This will order Person a1 and Person a2 based on age. Depending on the order you want (ascending vs descending) you can do the comparison as a2.GetAge().compareTo(a1.GetAge()); and that will work just fine as well.
You will also need to consider the case that both values are equal (which is when you would return 0).
