Java™ Application Development on Linux - Dator

3.2 Fundamental Language Elements67Example 3.8 A switch statement in Javaswitch (rval*k+zval){case 0:mylon.reset();break;case 1:case 4:// matches either 1 or 4y = zval+engrom;mylon.kuggle(y);break;default:// all other values end up hereSystem.out.println("Unexpected value.");break;}The default case is where control goes when no other case matches theexpression. It is optional—you don’t need to have one among your switch cases.Its location is also arbitrary; it could come first, but by convention programmersput it last in the sequence of cases, as a visual “catch all.”TIPFor whichever case is last (typically default), the ending break is redundantbecause control will continue outside the break—but we show it here in theexample, and use it ourselves in our code. Why? Well, code gets edited—forbug fixes and for feature additions. It is especially important to use break in allthe cases in switch statements that have no default case, but even inthose that do, we keep the break to avoid forgetting it, should another caseever be added or this last one relocated. We recommend that you do the same.3.2.3.2Looping and Related StatementsThe while statement. Like the while construct in other computer languages,the expression inside the parentheses is evaluated, and if true, thestatement following it is executed. Then the expression is evaluated again, andif still true, the looped statement is again executed. This continues until theexpression evaluates to false (Example 3.9).