title: Explain why constructor inject is better than other options
body: <p>In a Pro Spring 3 Book,
  Chapter 4 - Introduction IOC and DI in Spring - Page 59, In "Setter Injection vs. Constructor Injection" section, a paragraph says</p>
  
  <blockquote>
    <p>Spring included, provide a mechanism for ensuring that all dependencies are defined when
    you use Setter Injection, but by using Constructor Injection, you assert the requirement for the dependency in a container-agnostic manner"</p>
  </blockquote>
  
  <p>Could you explain with examples</p>