Difference between ArrayList HashMap

Difference between ArrayList HashMap

Answer: Below are differences:

ArrayList HashMap
ArrayList implements List interface (public class ArrayList<E> extends AbstractList<E> implements List<E>, RandomAccess, Cloneable, Serializable) HashMap implements Map interface (public class HashMap<K,V> extends AbstractMap<K,V> implements Map<K,V>, Cloneable, Serializable)
It works on collection of object and objects can be added to ArrayList using add method It works on collection of object with key-value pair and object can be added using put method
It allows null values and can be added to the list multiple times because it appends specified element to end of the list HashMap also allows null as key or value but duplicate key not allowed
ArrayList is roughly equivalent to the Vector class except that this class is unsynchronized HashMap class is roughly equivalent to the Hashtable except that this class unsynchronized and also permits nulls
Whenever elements added to ArrayList its capacity grows automatically and details of growth policy are not specified. HashMap default load factor is .75 means it grows by .75 by its initial size which can be control by its constructor

 Please have example java class:

package com.javahonk.arraylistmap;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map.Entry;
import java.util.Set;

public class ArraListHashMap {

    public static void main(String[] args) {
    
    System.out.println("ArrayList example\n");
    List<String> list = new ArrayList<String>();
    list.add("Java");
    list.add("Honk");
    list.add("Test");
    list.add(null);
    list.add(null);
    
    for (String string : list) {
        System.out.println(string);
    }
    
    System.out.println("\nHashMap example\n");
    HashMap<String, String> hashMap = 
            new HashMap<String, String>();
        hashMap.put("Java", "Java");
        hashMap.put("Honk", "Honk");
        hashMap.put("Test", "Test");
        hashMap.put("Test", "Test");
        hashMap.put(null,null);
        hashMap.put("abc",null);
        hashMap.put("def",null);
        Set<Entry<String, String>> set = hashMap.entrySet();
        for (Entry<String, String> entry : set) {
            
            System.out.println("Key: "+entry.getKey()
                +" Value: "+entry.getValue());      
        }

    }

}

Output: Difference between ArrayList HashMap

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