Program: How to get subset from sorted set?

To implement your own sorting functionality with TreeSet on user defined objects, you have to pass Comparator object along with TreeSet constructor call. The Comparator implementation holds the sorting logic. You have to override compare() method to provide the sorting logic on user defined objects. Now you can get range of object from the treeset by calling subSet() method.

package com.java2novice.treeset;

import java.util.Comparator;
import java.util.Set;
import java.util.TreeSet;

public class MySetSublist {

	public static void main(String a[]){
		
		TreeSet<String> ts = new TreeSet<String>(new MyStrComp());
		ts.add("RED");
		ts.add("ORANGE");
		ts.add("BLUE");
		ts.add("GREEN");
		ts.add("WHITE");
		ts.add("BROWN");
		ts.add("YELLOW");
		ts.add("BLACK");
		System.out.println(ts);
		Set<String> subSet = ts.subSet("GREEN", "WHITE");
		System.out.println("sub set: "+subSet);
		subSet = ts.subSet("GREEN", true, "WHITE", true);
		System.out.println("sub set: "+subSet);
		subSet = ts.subSet("GREEN", false, "WHITE", true);
		System.out.println("sub set: "+subSet);
	}
}

class MyStrComp implements Comparator<String>{

	@Override
	public int compare(String str1, String str2) {
		return str1.compareTo(str2);
	}
	
}

[BLACK, BLUE, BROWN, GREEN, ORANGE, RED, WHITE, YELLOW]
sub set: [GREEN, ORANGE, RED]
sub set: [GREEN, ORANGE, RED, WHITE]
sub set: [ORANGE, RED, WHITE]