title: Difference between slf4j and log4j on the basis of String creation
body: <p>In log4j if we write </p>
  
  <pre><code>**logger.debug("Processing trade with id: " + id + " symbol: " + symbol);**
  </code></pre>
  
  <p>it will create String in string pool but when we use slf4j we use parameter based like this</p>
  
  <pre><code>**logger.debug("Processing trade with id: {} and symbol : {} ", id, symbol);**
  </code></pre>
  
  <p>So what is the difference between these two statement, slf4j  will create String at run time or not ?</p>