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JAVA EXAMPLE PROGRAMS

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Program: How to create a TreeSet with comparator?


Description:

To implement your own sorting functionality with TreeSet, 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. Below example shows how to sort TreeSet using comparator.


Code:
package com.java2novice.treeset;

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

public class MySetWithCompr {

	public static void main(String a[]){
		
		TreeSet<String> ts = new TreeSet<String>(new MyComp());
		ts.add("RED");
		ts.add("ORANGE");
		ts.add("BLUE");
		ts.add("GREEN");
		System.out.println(ts);
	}
}

class MyComp implements Comparator<String>{

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

Output:
[BLUE, GREEN, ORANGE, RED]
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List Of All TreeSet Sample Programs:

  1. Basic TreeSet Operations.
  2. How to create a TreeSet with a List?
  3. How to read objects from TreeSet using using Iterator?
  4. Write a program to remove duplicate entries from an array.
  5. Write a program to find duplicate value from an array.
  6. How to create a TreeSet with comparator?
  7. Create TreeSet with comparator by user define objects.
  8. How to sort a TreeSet with user defined objects?
  9. How to get subset from sorted set?
  10. How to get least value element from a set?
  11. How to get highest value element from a set?
  12. How to avoid duplicate user defined objects in TreeSet?
Knowledge Centre
Java class can be private?
We can not declare top level class as private. Java allows only public and default modifier for top level classes in java. Inner classes can be private.
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About Author

I'm Nataraja Gootooru, programmer by profession and passionate about technologies. All examples given here are as simple as possible to help beginners. The source code is compiled and tested in my dev environment.

If you come across any mistakes or bugs, please email me to [email protected].

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Reference: Java™ Platform Standard Ed. 7 - API Specification | Java™ Platform Standard Ed. 8 - API Specification | Java is registered trademark of Oracle.
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