title: Why does my String turn into Integers instead of letters after I add characters with +?
body: <p>So this is the task: Given a string, return a string where for every char in the original, there are two chars.</p>
  <p>And I don't understand why its output are numbers instead of letters, I tried doesn't work?</p>
  <pre><code>public String doubleChar(String str) {
    String s = &quot;&quot;;
    for(int i=0; i&lt;str.length(); i++){
    s +=  str.charAt(i) + str.charAt(i);
    
    }
      return s;
  }
  </code></pre>
  <p>Expected :</p>
  <blockquote>
  <p>doubleChar(&quot;The&quot;) → &quot;TThhee&quot;</p>
  <p>doubleChar(&quot;AAbb&quot;) → &quot;AAAAbbbb&quot;</p>
  </blockquote>
  <p>Output:</p>
  <blockquote>
  <p>doubleChar(&quot;The&quot;) → &quot;168208202&quot;</p>
  <p>doubleChar(&quot;AAbb&quot;) → &quot;130130196196&quot;</p>
  </blockquote>