StdOut not recognized in Java : <p>I'm new to Java and am trying to implement some example code from a book on algorithms:</p>

<pre><code>public class ThreeSum {
    public static int count(int[] a)
    {
        int N = a.length;
        int cnt = 0;
        for (int i = 0; i &lt; N; i++)
            for (int j = i+1; j &lt; N; j++)
                for (int k = j+1; k &lt; N; k++)
                    if (a[i] + a[j] + a[k] == 0)
                        cnt++;
        return cnt;
    }

    public static void main(String[] args)
    {
        int[] a = In.readInts(args[0]);
        StdOut.println(count(a));
    }
}
</code></pre>

<p>In Netbeans 7.2, I entered this code in a New File in a New Project. However, I notice that the lines in the client program with <code>In</code> and <code>StdOut</code> are underlined with red squiggly lines and have warnings leading to suggestions to create the class (see below).</p>

<p><a href="https://i.stack.imgur.com/26WAT.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/26WAT.png" alt="enter image description here"></a></p>

<p>How could I get rid of these warnings? Do I have to import any libraries? Also, how could I run the main program with some example input in the Netbeans environment?</p>
