Comparator..

[Preethi Dev]

Hi ,this from learnkey master exam.

import java.util.*;

class switch2
{

public static void main(String args[])
{
String[] sa={"Good","Gud","Bad","Ugly"};
Comparator<String> best=new Comparator<String>()
{
public int compare(String s1,String s2)
{
return s2.charAt(1)-s1.charAt(1);
}
};
Arrays.sort(sa,best);
for(String s:sa)
System.out.println(s);
}
}

output is gud,good,Ugly,bad.
can anyone explain me the logic of compare method using the above code?

Thanks
Preetha

[Ninad Kulkarni]

You can refer to java API documentation
That doc says following things

I expalin with your code in short

public int compare(String s1,String s2)
{
return s2.charAt(1)-s1.charAt(1);
}

comparator sorts objects according to the values return by compare method that are 1, 0 and -1

when s1-s2 results 1 then s1 is greater than s2
when s1-s2 results 0 then s1 and s2 are equal
when s1-s2 results -1 then s1 is less than s2

And masre exam code is doing s2-s1 in compare method if this is the case then comparator is sorting objects in descending order

I hope this clears to you and inform me if I am wrong in somewhere in my explaination

[M Srilatha]

One addition to what Ninad has said:

Here in this example, compare() method sorts the objects based on its character at index 1 and in descending order.

Hope this helps!