title: What is the significance of class data type in java?
body: <p>Noob question.</p>
  
  <p>I have been programming at basic level for quite a while but I have trouble understanding class data type.</p>
  
  <p>when we say <code>int a = 9;</code>
  it means a is of data type int meaning it can contain only integers.</p>
  
  <p>like wise for String, boolean, double, float etc.</p>
  
  <p>But consider the following code:</p>
  
  <pre><code>Class Node {
  
  Node next = null;
  int data;
  
  public Node(int d){ data = d; }
  
  void append(int d)
      {
          blah blah blah
          ..............
      }
  }
  </code></pre>
  
  <p>What does <code>Node next = null;</code> mean? I can understand the effort to create an object with</p>
  
  <pre><code>Node next = new Node();
  </code></pre>
  
  <p>and then try to manipulate the next object.</p>