title: StdRandom, StdOut, Insertion cannot be resolved
body: <p>This code should implement sorting.<br>
  I have 3 errors:<br>
  "StdRandom cannot be resolved",<br>
  "StdOut cannot be resolved",<br>
  "Insertion cannot be resolved".<br>
  May be there are some libraries to import?</p>
  
  <pre><code>public class randomDoubles 
  {
  public static void main(String[] args)
  {
  
      int N = Integer.parseInt(args[0]);
      Double[] a = new Double[N];
      for(int i = 0; i &lt; N; i++)
          a[i] = StdRandom.uniform(); // error: StdRandom cannot be resolved
      Insertion.sort(a);                  // error: Insertion cannot be resolved
      for (int i = 0; i &lt; N; i++)
          StdOut.println(a[i]);       // error: StdOut cannot be resolved
  }
  }
  </code></pre>