Module 1, part 4. Variables, declarations, and assignments
Introduction
This part 4 introduces you to variables, the Java declaration (of a variable), and the assignment statement. We also talk about strong versus weak typing —Java is strongly typed, while Matlab and C are weakly typed.
Contents
| No. | Topic | Discussion |
|---|---|---|
| 1. | The variable and its declaration (blecture doc ppt.pdf) |
Java's concept of variable is similar to that in most other languages: a named box with a value in it. In Java, a variable must be declared before it is used, and it has a type. |
| 2. | The assignment statement (blecture doc ppt.pdf) |
Execution of an assignment statement stores a value in a variable. Learn also about the initializing declaration and narrower and wider types. |
| Reading for parts 1 and 2: | Gries/Gries, Section 1.2, pp. 26–29. | |
| 3. | Promoting and casting (PLive lectures 6-2.3..4) Reading: Gries/Gries, Section 1.3.1,pp. 19–20. |
In several circumstances, Java will automatically promote a value to a wider type. In addition, you, the programmer can explicitly cast a value from one type to another. This lecture explains how and why this is done. |
| 4. | char as an integral type. Reading: Gries/Gries, Sec. 6.5, pp. 224–225. PLive lectures 6-5–2..4. |
You are not responsible for this material, but reading it will help you understand how characters are represented. |
| 5. | Conditional expression (html) | The conditional expression evaluates one of two subexpressions based on a condition (a boolean expression). You will use it in assignment 1. |
| 6. | Safety and strong typing (html) | This little essay will give you some understanding of why strong typing is used in DrJava. |
| 7. | Lab 01. Expressions, variables, declarations, and assignments | Lab 01 gives you practice in DrJava with basic concepts of expression, variables, etc. Do this on your own, if you want to show the results to a consultant to make sure you did everything right, they will be happy to talk to you. |
| 8. | Self-help exercises. Gries/Gries, Section 1.2.1, pp. 29–30. |
It is important that you fully understand declarations and the assignment statement. These exercises will help you in this endeavor. |
| 9. | Quiz 1. Assignments | This quiz will test your understanding of assignments and declarations. See a consultant in the lab at your convenience. You cannot take the test for module 1 until you have passed this (and other) quizzes. |