title: Regex for replacing numbers to characters
body: <p>I have a string such as <code>"kdf343kkkk4k4"</code>. I need to find the numbers on this string and replace a number with a specific character like <code>'X'</code>. Output should be like <code>"kdfXXXkkkkXkX"</code>.</p>
  
  <p>Each and every number should be replaced with <code>'X'</code>:</p>
  
  <pre><code>343 = XXX
  </code></pre>
  
  <p>I tried with regex replace but it replaces all together.</p>
  
  <pre><code>343 = X
  </code></pre>
  
  <p>I am using the following regular expression:</p>
  
  <pre><code>x.replaceAll("([0-9])+", "X");
  </code></pre>
  
  <p>Please explain to me how to do this.</p>