title: Why does "3.5".matches("[0-9]+") return false?
body: <p>I use the method <code>String.matches(String regex)</code> to find if a string matches the regex expression</p>
  
  <p>From my point of view the regular expression <code>regex="[0-9]+"</code> means a String that contains at least one figure between 0 and 9</p>
  
  <p>But when I debug <code>"3.5".matches("[0-9]+")</code> it returns false.</p>
  
  <p>So what is wrong ?</p>