Lists, Logic, and Loops - Java 6 - page 92

Using if , you can include only a single statement as the code to execute if the test
expression is true and another statement if the expression is false.

However, as you learned earlier today, a block can appear anywhere in Java that a single
statement can appear. If you want to do more than one thing as a result of an if state-
ment, you can enclose those statements inside a block. Note the following snippet of
code, which was used on Day 1, “Getting Started with Java”:

if (temperature > 660) {
status = “returning home”;
speed = 5;

}

The if statement in this example contains the test expression temperature > 660 . If the
temperature variable contains a value higher than 660, the block statement is executed,
and two things occur:

The status variable is given the value returning home .

n

The speed variable is set to 5 .

n

If the temperature variable is equal to or less than 660, the entire block is skipped, so
nothing happens.

All if and else statements use Boolean tests to determine whether statements are exe-
cuted. You can use a boolean variable itself for this test, as in the following:

if (outOfGas)
status = “inactive”;

The preceding example uses a boolean variable called outOfGas . It functions exactly like
the following:

if (outOfGas == true)
status = “inactive”;

switch Conditionals
A common programming practice is to test a variable against a value, and if it doesn't
match, test it again against a different value, and so on.

This approach can become unwieldy if you're using only if statements, depending on
how many different values you have to test. For example, you might end up with a set of
if statements something like the following:

if (operation == '+')
add(object1, object2);