void type not allowed here (java) (s != null)
<p>I have this code, it says void type not allowed here (where I put the //error comment)
When I delete the &amp;&amp;..... it wont give the error</p>

<pre><code>public void actionPerformed(ActionEvent ae) {
if (ae.getSource() == ok) {
    Contact nweC = null;


    String vnm = tfVoor.getText();
    String anm = tfAchter.getText();
    String em = tfEmail.getText();
    if (em.trim().length() &gt; 0 &amp;&amp; !hetBoek.heeftContact(em)) {
        nweC = new Contact(vnm, anm, em);
    } else {
        tfEmail.setText("");
        JOptionPane.showMessageDialog(null, "Onjuist emailadres", "Mislukt", JOptionPane.PLAIN_MESSAGE);
    }
    //error if (nweC != null &amp;&amp; hetBoek.voegContactToe(nweC)) {
                JOptionPane.showMessageDialog(null, "Toevoegen gelukt", "Succes", JOptionPane.PLAIN_MESSAGE);
    }
} else if (ae.getSource() == cancel) {
    tfVoor.setText("");
    tfAchter.setText("");
    tfEmail.setText("");
} else if (ae.getSource() == toon) {
    String s = hetBoek.toString();
    JOptionPane.showMessageDialog(null, s, "Druk op OK",
    JOptionPane.PLAIN_MESSAGE);
}
}
</code></pre>

<p>I hope someone can help me! thanks</p>
