title: When i need to use hashMap because it is not synchronized
body: <blockquote>
    <p>I know  Hashtable is synchronized, whereas HashMap is not.</p>
  </blockquote>
  
  <p>As per my knowledge synchronization means accessing a object at a time by one thread.</p>
  
  <p>So there is no problem while using Hashtable. But in my project I am using HashMap. I used it 
  in many places. Till now I did not get any problem with HashMap.</p>
  
  <p>So when the synchronization concept will come into the picture(i.e using HashMap).</p>
  
  <p>Can I use HashMap in all places where I am using HashTable?</p>
  
  <p>Can I use HashTable in all places where I am using HashMap?</p>