An elegant way to join arrays of arrays of strings by two different separators in java by stream
<p>We can use <code>String.join</code> to concatenate a list of strings by a separator.</p>

<p>My problem now is I have an array of arrays of strings.</p>

<p>e.g </p>

<pre><code>[(a, b), (c, d), (e,f)], 
</code></pre>

<p>I want to join <code>a&amp;b, c&amp;d, e&amp;f</code> by colon, and space between these pairs.</p>

<p>like</p>

<pre><code>a:b c:d e:f
</code></pre>

<p>Is there an elegant way to do this?</p>

<p>Follow up:</p>

<p>If you do this with a loop nested with another loop then you create a lot of String variables in your pool, which does not look very good</p>