Questions

• Reading?
• Homework?
• Quiz?

Activity - Homework Project

Record your participation in Piazza clicker question Lesson2 Q1

We are going to start at the beginning and set up hw1b together

• start your IDE,
• make a project.
  • call it hw1b_in_class
• read the assignment to see what we need to do
• notice it shows syntax errors as you go
  • look at the quick fixes but be careful
• run by right clicking on StringsForAll and choosing Run as Java Application
• copy/paste the code into Codecheck
• Click submit
• upload report to Canvas - you will need to upload it again with the other two files

Activity - Deciphering Syntax Errors

Record your participation in Piazza clicker question Lesson2 Q2

One of the challenges in learning a new programming language is to be able to decipher syntax error messages

Let's practice

• Start a new project in your IDE
• Get the file, ErrorDeciphering.java
• Create a class with the file
• Look at the first error
• What does the error say? What do you think it means?
• Fix the error
• Look at the next error
• What does the error say? What do you think it means?
• Fix the error
• Repeat for all the errors

Activity - Accessor and mutators

Record your participation in Piazza clicker question Lesson2 Q3

• What is an accessor method?
• What is a mutator method?
• Look at the Rectangle class in the API class. Find an accessor. Find a mutator.

Activity - Accessors and mutators

Record your participation in Piazza clicker question Lesson2 Q4

Look at the String class in the API class. Find an accessor. Find a mutator.

Activity - Compiling

Record your participation in Piazza clicker question Lesson2 Q5

What is created when you compile a Java source file

1. object code
2. byte code
3. You do not compile Java. It is an interpreted language
4. None of the above

Concept - new operator

Objects are always created using the new operator

• This creates an object reference variable today

  Day today;

  no object has been created
• This creates an object of type Day

  new Day();

• This creates an object and assigns it to a variable.

  Day today = new Day();

Concept - creating a String object

• To create a String object

  String cat = "Corky";

• What happened to the new operator?

Activity - Creating objects

Record your participation in Piazza clicker question Lesson2 Q6

Which statement creates a Rectangle object?

1. Rectangle box;
2. box = Rectangle(10, 20, 100, 50);
3. new Rectangle(10, 20, 100, 50);