title: Alternative for String.join in Android?
body: <p>I want to concatenate an ArrayList with commas as separators. I found <a href="https://stackoverflow.com/questions/1978933/a-quick-and-easy-way-to-join-array-elements-with-a-separator-the-opposite-of-sp">this answer</a>, stating it's possible to use <code>String.join</code> in Java.</p>
  
  <p>When I try to use this however, Android Studio gives the following error:</p>
  
  <blockquote>
    <p>Cannot resolve method 'join(java.lang.String, java.lang.String,
    java.lang.String, java.lang.String)'</p>
  </blockquote>
  
  <p>Is there a good, concise alternative for Android Studio (instead of using a for loop)?</p>