title: Java check if string only contains english keyboard letters
body: <p>I want to disallow users from using any special characters in their name.
  They should be able to use the whole english keyboard, so</p>
  <pre><code>a-z, 0-9, [], (), &amp;, &quot;, %, $, ^, °, #, *, +, ~, §, ., ,, -, ', =, }{
  </code></pre>
  <p>and so on. So they should be allowed to use every &quot;normal&quot; english character which you can type with your keyboard.</p>
  <p>How can I check that?</p>