Lab07 Hints and Tips

Part 0 -- Using an ArrayList

Please do this part before doing the Part 1 in the Lab guide.

1. Create a new Java project named Lab07Extra.
2. Create a new package in the project named logic, then copy the classes in the logic package from the Lab03 project to the new package.
3. Create a new class named TestCustomer in the test package with a main method.
4. Complete main as follows:
   1. Create an ArrayList collection using its zero-argument constructor:

      ArrayList<Customer> myList = new ArrayList<>();
      			

   2. Create a few Customer objects and store them in the ArrayList. To add the first Customer, your code might look something like:

      Customer c1 = new Customer("Slim", "Dunlap", "K", "Jr.");			
      myList.add(c1);			
        			  

   3. Write an iteration loop using the enhanced for loop that retrieves each Customer from the ArrayList and prints its reference to the console. Use the code on page 8-12 in the course notes as a guide, but note that your collection contains Customer object references instead of Integer object references.
5. Run and test your program.

Part 1

• Look up the java.util.Stack class in the JavaDoc. Especially look at its constructors, the push, pop and isEmpty methods.
• In Step 4a, your code might look like:

  // retrieve String from user
  System.out.print("Enter a string: ");
  String input = scanner.nextLine();
    		  

  Before you loop through and process the input String, create an empty java.util.Stack<Character> and define an int initialized to zero which you can increment when your loop finds a nesting error.

• The loop to process the input String might look something like:

  for(int i=0; i<input.length(); i++)
  {
     char ch = input.charAt(i);
     . . .
  }
  		  

• Remember that collections like Stack only hold objects, not primitives. but that Java can "autobox" primitive values into wrapper-class objects. So you push like:

  stack.push(ch);		  
  		  

  To retrieve the top Character on the stack and access its char value, use code like:

  char found = stack.pop();		  
  		  

• To determine if a "found" end bracket matches a start bracket, you might use a switch - case statement:

  switch (found)
  {
      case ')':
        if (ch != '(')
        {
            errorCount++;
            System.out.println("Error: expected '(', found " + found);
        }
        . . .
  }
            

Part 2

• In Step 1, part 1, you should write a for loop that loops 100 times and each time through the loop, create an Integer object using the loop index. Then store the Integer object in the ArrayList.
  
  Assuming you named your ArrayList reference list, you can print the collection like:

  System.out.println(list);