Chapter 4: Decision Structures and Boolean Logic - Java Language Companion

Rlational Operators and the if statement

> Greater than

< Less than

>= Greater than or equal to

<= Less than or equal to

== Equal to

! = Not equal to

Format of if statement:

if (BooleanExpression)

{

statement;

statement;

etc;

}

If Boolean expression is TRUE, the statements inside the curly braces are executed. If FALSE, they’re skipped. (statements are conditionally executed)

If if statement has only ONE conditionally executed statement, doesn’t have to be in curly braces:

if (BooleanExpression)

statement;

Dual Alternative Decision Structures

Use if-else statement in Java to create a dual alternative decision structure. This is the format of the if-else statement:

    if (BooleanExpression)

    {

            statement;

            statement;

            etc;

    }

    else

    {

            statement;

            statement;

            etc;

    }

An if-else statement has two parts:

• if clause

• else clause

If TRUE, if clause is executed. If FALSE, else clause is executed

Has two sets of conditionally executed statements. One set executed only if Boolean expression is true, other set executed when it’s false. Both sets cannot be executed together.

If either set of conditionally executed statements contains only one statement, the curly braces aren’t required.

    if (BooleanExpression)

            statement;

    else

            statement;