Sams Teach Yourself Java™ in 24 Hours (Covering Java 7 and Android)

ptg7068951

WHAT YOU’LL LEARN IN

THIS HOUR:

.Creating variables

.Using the different types of

variables

.Storing values into

variables

.Using variables in mathe-

matical expressions

.Storing one variable’s value

into another variable

.Increasing and decreasing

a variable’s value

In Hour 2, “Writing Your First Program,” you used a variable, a special stor-
age place designed to hold information. The information stored in vari-
ables can be changed as a program runs. Your first program stored a string
of text in a variable. Strings are only one type of information that can be
stored in variables. They also can hold characters, integers, floating-point
numbers, and objects.

During this hour, you learn more about using variables in your Java
programs.

Statements and Expressions

Computer programs are a set of instructions that tell the computer what to
do. Each instruction is called a statement. The following example from a
Java program is a statement:

int highScore = 450000;

You can use brackets to group a set of statements together in a Java pro-
gram. These groupings are called blockstatements. Consider the following
portion of a program:

1: public static voidmain(String[] args) {
2: int a = 3;
3: int b = 4;
4: int c = 8 * 5;
5: }

Lines 2–4 of this example are a block statement. The opening bracket on
Line 1 denotes the beginning of the block, and the closing bracket on
Line 5 denotes the end of the block.

HOUR 5

Storing and Changing Information

in a Program