title: Adding new value to String array based on condition
body: <p>String Array contains values like  {'2','4','8'}</p>
  
  <p>if 8 is present, want to add 999 to it,if string array contains 999 want to add 8 to it.</p>
  
  <p>If both 8 and 999 are present in array no need to add any value to array.</p>