title: Breaking List of list to a single list java
body: <p>I have a java method that returns below output:</p>
  <pre><code>List&lt;CompletableFuture&lt;List&lt;String&gt;&gt;&gt; futureResponselist;
  </code></pre>
  <p>How can I construct a single list from this data? As I have to iterate the final output and do some operation with the &quot;string&quot; param that is present inside.</p>
  <p>I want all the string values present inside these lists in a final single list.</p>
  <p>It should be as: <code>List&lt;String&gt;</code>  My futureResponselist size is 3.so the conversion TO List should happen in nonblocking way</p>