TREESET DEMO

import java.util.*; 
 
public class TreeSetDemo 
{    
    class MyComparator implements Comparator<String> 
 { public int compare(String s1, String s2) 
  { if(s1.compareTo(s2)<0)  
   return -1; 
    if(s1.compareTo(s2)>0)  
     return +1; 
    return 0; 
  } 
 } 
 public static void main(String[] args) 
 { 
  TreeSet<String> ts =  
                 new TreeSet<>(new TreeSetDemo().new MyComparator()); 
  ts.add("hello"); ts.add("world"); ts.add("version"); 
  ts.add("main"); ts.add("method"); 
   
  System.out.println("Contents: " + ts); 
  System.out.println(); 
   
  System.out.println("Higher than \"main\": " + ts.higher("main")); 
  System.out.println("Lower than \"main\": " + ts.lower("main")); 
  System.out.println(); 
     
  SortedSet s = ts.tailSet("method"); 
  System.out.println("TailSet from \"method\": " + s); 
  s = ts.headSet("method"); 
  System.out.println("HeadSet from \"method\": " + s); 
  System.out.println(); 
   
  Iterator it = ts.iterator(); 
  System.out.print("Iteration: "); 
  while(it.hasNext()) 
   System.out.print(it.next()+" "); 
   
  System.out.println(); 
  System.out.println(); 
  Iterator it2 = ts.descendingIterator(); 
  System.out.print("Iteration Descending: "); 
  while(it2.hasNext()) 
   System.out.print(it2.next()+" "); 
   
  System.out.println(); 
  System.out.println("First one: " + ts.pollFirst()); 
  System.out.println("Last one: " + ts.pollLast()); 
  System.out.println("Contents: " + ts); 
  } 
}