title: Add Object Collection to another Object Collection without iterating
body: <p>I have a collection of objects objcol1(example Collection of cities in a state) and another object collection objcol2(example collection of cities in a country). Now I am querying for objcol1 and I want to add it to objcol2. I can do this by iterating through objcol1 and adding one by one to objcol2 but can I directly add objcol1 to objcol2 like 
  <strong>objcol2.add(objcol1);</strong></p>
  
  <p>Can anyone tell me whether it is possible without iterating? If yes please explain me the process</p>