Java™ Application Development on Linux - Dator

66Chapter 3An Experienced Programmer’s Introduction to Javacomment consists of everything from the opening /* to the closing */sequence.3.2.3.1 Conditional ExecutionAn experienced programmer probably only needs to see examples of if andother such statements to learn them. It’s only a matter of syntax. Java breaksno new ground here; it adds no new semantics to conditional executionconstructs.The if-else statement. The if can take a single statement without anybraces, but we always use the braces as a matter of good style (Example 3.7).Example 3.7 A compound Java if-else statementif (x < 0) {y = z + progo;} else if (x > 5) {y = z + hmron;mylon.grebzob();} else {y = z + engrom;mylon.kuggle();}TIPAn important thing to remember about the Java if statement (and all otherconditional tests, such as while, do-while, and for) is that, unlike C/C++,its expression needs to evaluate to a boolean. In C/C++, numeric expressionsare valid, any nonzero value being considered true, but not so in Java.The switch statement. For a multiway branch Java, like C/C++, has aswitch statement, though the Java version of switch is a bit more restrictive.Example 3.8 shows the syntax.In Java, the expression in the switch statement must evaluate to eitheran int or a char. Even short and long are not allowed.As in C/C++, be sure to put the break statement at the end of each case,or else control will flow right into the next case. Sometimes this is the desiredbehavior—but if you ever do that deliberately, be sure to add a comment.