Java Collection Examples : How To Remove Duplicate Elements From An Array

Intro

This examples will demonstrates how to remove duplicate elements from an array. To get it, you have to convert an array into a Set collection first.

Examples

package com.freesamplecode.java.array;

import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

public class RemoveDuplicateElementDemo {
	public static void main(String[] args){
		
		   // Step 1:  Prepare a duplicate array
		   String[] strArray = { "A", "B", "B", "C", "A", "D", "B", "A", "B", "D" };
		   
		   System.out.println("Original Array : "+Arrays.toString(strArray));
		   
		   // Step 2 : Convert an array to list
		   List list = Arrays.asList(strArray);
		   
		   // Step 3 : Create a Set object from list
		   Set set = new HashSet(list);
		   
		   // Step 4 : Create an array object to hold values from set
		   String[] newArray = new String[set.size()];
		   
		   // Step 5 : Convert a Set into an Array
		   set.toArray(newArray);
		   
		   // Step 6 : Display value after removing duplicate to console
		   System.out.print("After removing duplicates: "+Arrays.toString(newArray));
		   
		   
		   
	}
}

Output

Original Array : [A, B, B, C, A, D, B, A, B, D]
After removing duplicates: [D, A, B, C]

Screenshot

Java Collection Examples : How To Sort A Vector In Ascending Order

Intro

This examples will demonstrates how to sort a vector's elements in ascending order using Collections.sort() method.

Examples

package com.freesamplecode.java.vector;

import java.util.Collections;
import java.util.Vector;

public class SortVectorAscendingDemo {
 public static void main(String[] args){
  
  //create an object
  Vector vector = new Vector();
  
  //adding an element
  vector.add("Banana");
  vector.add("Apple");
  vector.add("Strawberry");
  vector.add("Cherry");
  vector.add("Pinneaple");
  vector.add("Golden Fruit");
  
  System.out.println("Vector element before sorting : "+vector);
  
  Collections.sort(vector);
  
  System.out.println("Vector element after sorting : "+vector);
 }
}

Output

Vector element before sorting : [Banana, Apple, Strawberry, Cherry, Pinneaple, Golden Fruit]
Vector element after sorting : [Apple, Banana, Cherry, Golden Fruit, Pinneaple, Strawberry]

Screenshot

Java Examples : How To Convert A List Into An Array

Intro

This examples, will demonstrates how to convert a list into an array. To convert from ArrayList class to array object, you can use ArrayList.toArray() method.

Example

package com.freesamplecode.java.arraylist;

import java.util.ArrayList;
import java.util.List;

public class ConvertListToArrayDemo {
 public static void main(String[] args){
  List listOfFruits = new ArrayList();
  listOfFruits.add("Apple");
  listOfFruits.add("Banana");
  listOfFruits.add("Cherry");
  listOfFruits.add("Pinneaple");
  
  String[] fruitsArray = (String[]) listOfFruits.toArray(new String[0]);
  for(String fruit :fruitsArray){
   System.out.println(fruit);
  }
 }
}

Output

Apple
Banana
Cherry
Pinneaple

Screenshot

Java Examples : How To Convert An Array To A List

Intro

This examples, will demonstrates how to convert an array into a list. To convert an array into a list format, you can use Arrays.asList() method.

Examples

package com.freesamplecode.java.array;

import java.util.Arrays;
import java.util.List;

public class ConvertArrayToListDemo {
 public static void main(String[] args){
  
  //declare an array
  String[] fruits = {"Aple","Banana","Cherry","Pinneaple"};
  
  //convert an array into list
  
  List listOfFruits = Arrays.asList(fruits);
  
  //iterate list data
  
  for(String fruit : listOfFruits){
   System.out.println(fruit);
  }
  
 }
}

Output

Aple
Banana
Cherry
Pinneaple

Screenshot

Java Collection Examples : Simple HashMap Examples

Intro

This examples, will demonstrates how to create a simple HashMap examples.

Examples

package com.freesamplecode.java.hashmap;

import java.util.HashMap;

public class SimpleHashMapDemo {
 public static void main(String[] args){
  HashMap hashMap = new HashMap();
  
  //put data into hashmap
  hashMap.put("name", "Nursalim");
  hashMap.put("country", "Indonesia");
  hashMap.put("Occupation", "Java Programmer");
  
  //getting data from hashmap
  System.out.println("Name : "+hashMap.get("name"));
  System.out.println("Country : "+hashMap.get("country"));
  System.out.println("Occupation : "+hashMap.get("Occupation"));
 }
}

Output

Name : Nursalim
Country : Indonesia
Occupation : Java Programmer

Screenshot

Java Collection Examples : How To Get All Elements In ArrayList Using Iterator

Intro

This examples. will demonstrates how to get all element in the ArrayList class using Iterator class. ArrayList are the class implementations of the List interfaces.

Examples

package com.freesamplecode.java.arraylist;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class GetAllElementListDemo {
 public static void main(String[] args){
  List list = new ArrayList();

                // add more elements into list

  list.add("Nursalim");
  list.add("Iskiyati");
  list.add("Nurul Hikmah");
  list.add("Nani Indriyani");
  

                // iterate all list elements  

  Iterator it = list.iterator();
  
  while(it.hasNext()){
   System.out.println(it.next());
  }
 }
}

Output

Nursalim
Iskiyati
Nurul Hikmah
Nani Indriyani

Screenshot

Java Collection Examples : How To Get All Elements In Vector Using Iterator

Intro

This tutorials, will introduces how to get all elements in vector using Iterator.

Examples

package com.freesamplecode.java.vector;

import java.util.Iterator;
import java.util.Vector;

public class GetElementIteratorDemo {
 public static void main(String[] args){
  Vector vector = new Vector();
  vector.add("Nursalim");
  vector.add("Iskiyati");
  vector.add("Nurul Hikmah");
  vector.add("Nani Indriyani");
  
  Iterator it = vector.iterator();
  while(it.hasNext()){
   System.out.println(it.next());
  }
 }
}

Output

Nursalim
Iskiyati
Nurul Hikmah
Nani Indriyani

Screenshot