Append a single character to a string or char array in java?

Is it possible to append a single character to the end of array or string in java

for example:

    private static void /*methodName*/ () {            
          String character = "a"
          String otherString = "helen";
          //this is where i need help, i would like to make the otherString become 
         // helena, is there a way to do this?               
      }