title: Create a Map out of a List of String(s) with streams
body: <p>I have a <code>List</code> of <code>String</code>(s), but I want to convert it into a <code>Map&lt;String, Boolean&gt;</code> from the <code>List&lt;String&gt;</code>, making all of the <code>boolean</code> mappings set to <em>true</em>. I have the following code.</p>
  
  <pre><code>import java.lang.*;
  import java.util.*;
  class Main {
    public static void main(String[] args) {
      List&lt;String&gt; list = new ArrayList&lt;&gt;();
      list.add("ab");
      list.add("bc");
      list.add("cd");
      Map&lt;String, Boolean&gt; alphaToBoolMap = new HashMap&lt;&gt;();
      for (String item: list) {
        alphaToBoolMap.put(item, true);
      }
      //System.out.println(list); [ab, bc, cd]
      //System.out.println(alphaToBoolMap);  {ab=true, bc=true, cd=true}
    }
  } 
  </code></pre>
  
  <p>Is there a way to reduce this using streams?</p>