How to convert Array to TreeSet

import java.util.Arrays;
import java.util.Set;
import java.util.TreeSet;

public class ArrayToTreeSet {

public static void main(String[] args) {

String [] arr={"java","php","html","json","ajax"};

for (String str : arr) {
System.out.println("Array element is ="+str);
}

Set<String> ts = new TreeSet<String>(Arrays.asList(arr));

// print treeset

for (String str : ts) {
System.out.println("TreeSet Element = "+str);
}

}

}

Array element is =java

Array element is =php

Array element is =html

Array element is =json

Array element is =ajax

TreeSet Element = ajax

TreeSet Element = html

TreeSet Element = java

TreeSet Element = json

TreeSet Element = php

TreeSet provides addAll() method , which can adds all of the elements in the specified collection to this set if they’re not already present (optional operation).

Syntax :

public boolean addAll(Collection<? extends E> c) {

}

Parameters – It Takes as parametric c collection containing elements to be added to this set
Returns Value – It’s true if this set changed as a result of the call
Exception – It’s throws following exceptions
UnsupportedOperationException – Throws if the addAll operation is not supported by this set
ClassCastException – Throws if the class of an element of the given collection prevents it from being added to this set
NullPointerException – if the specified collection contains one or more null elements and this set does not permit null elements, or if the given collection is null
IllegalArgumentException – Throws  if some property of an element of the specified collection prevents it from being added to this set.

Algorithms :

1. Create array.
2. Create List from array using Arrays.asList() .
3. Add new created list in TreeSet with the help of addAll() method.

import java.util.Arrays;
import java.util.Set;
import java.util.TreeSet;

public class TreeSetAddAll {
	
	public static void main(String[] args) {
		
		String [] arr={"java","php","html","json","ajax"};
		
		Set<String> treeSet = new TreeSet<>();
		
		treeSet.addAll( Arrays.asList(arr));
		
		System.out.println("treeset element are :"+ treeSet);
		}
  }

Output:

treeset element are :[ajax, html, java, json, php]

3. Using Collections addAll() method

We can store array in set java by using Collections addAll() method . Let’s see code example for convert array to set java using collection addAll().

import java.util.Collections;
import java.util.Set;
import java.util.TreeSet;

public class TreeSetAddAll {
	
	public static void main(String[] args) {
		
		String [] arr={"java","php","html","json","ajax"};
		
		Set<String> treeSet = new TreeSet<>();
		
		Collections.addAll(treeSet, arr);
		
		System.out.println("treeset element are :"+ treeSet);
		}
  }

Output :

treeset element are :[ajax, html, java, json, php]

4. Using for loop

In this way we will add element in TreeSet one by one.

Algorithms :

1. Create array and add element in to it.
2. Create TreeSet.
3. Iterate array and one by one add element in TreeSet Using add() method.

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

public class TreeSetAddAll {

	public static void main(String[] args) {

		String[] arr = { "java", "php", "html", "json", "ajax" };

		Set<String> treeSet = new TreeSet<>();
		for (String element : arr) {
			treeSet.add(element);
		}

		System.out.println("treeset element are :" + treeSet);
	}
}

Output :

treeset element are :[ajax, html, java, json, php]

References :

A Guide to TreeSet                                                                                                              Java Doc – TreeSet