title: Running Java Programs on the Command Prompt
body: <p>I have done a lot of researching on this concept but I can't seem to run a java program on the command prompt. Let's say we had a simple program like this:</p>
  
  <pre><code>public class Hello_World {
      public static void main(String[] args) {
          System.out.println("Hello World!");
      }
  }
  </code></pre>
  
  <p>On the command prompt I tried:</p>
  
  <pre><code>javac Hello_World.java
  </code></pre>
  
  <p>But I get:</p>
  
  <pre><code>'javac' is not recognized as an internal or external command, operable program or batch file
  </code></pre>
  
  <p>So I compiled it on BlueJ and then did this:</p>
  
  <pre><code>java Hello_World.java
  </code></pre>
  
  <p>But it said "cannot load or find main class Hello_World"!</p>
  
  <p>I am currently using Windows 7, and made the programs on Notepad++ and BlueJ (to compile).
  Any suggestions? Thanks!</p>