//client public class AmazonClient {  private InterpreterContext context;  public AmazonClient(InterpreterContext context) {this.context = context; }  /**  * Interprets a string input of the form   *   movies | books by title | year | name '<string>'  */ public String interpret(String expression) {//we need to parse the string to determine which expression to use AbstractExpression exp = null; String[] stringParts = expression.split(" ");String main = stringParts[0];String sub = stringParts[2];//get the query partString query = expression.substring(expression.firstIndexOf("'"), expression.lastIndexOf("'"));if(main.equals("books")){if(sub.equals("title"){  exp = new BookTitleExpression(query);}if(sub.equals("year"){   exp = new BookYearExpression(query);}}else  if(main.equals("movie"))  {//similar statements to create movie expressions  }    if(exp != null){exp.interpret(context);} }   public static void main(String[] args)  {InterpreterContext context  = new InterpreterContext("http://aws.amazon.com/");AmazonClient client = new AmazonClient();//run a queryString result = client.interpret("books by author 'John Connolly'");System.out.println(result); }}