Читать книгу OCP Oracle Certified Professional Java SE 17 Developer Study Guide - Jeanne Boyarsky - Страница 211

One facet of break, continue, and return that you should be aware of is that any code placed immediately after them in the same block is considered unreachable and will not compile. For example, the following code snippet does not compile:

int checkDate = 0; while(checkDate<10) { checkDate++; if(checkDate>100) { break; checkDate++; // DOES NOT COMPILE } }

Even though it is not logically possible for the if statement to evaluate to true in this code sample, the compiler notices that you have statements immediately following the break and will fail to compile with “unreachable code” as the reason. The same is true for continue and return statements, as shown in the following two examples:

int minute = 1; WATCH: while(minute>2) { if(minute++>2) { continue WATCH; System.out.print(minute); // DOES NOT COMPILE } } int hour = 2; switch(hour) { case 1: return; hour++; // DOES NOT COMPILE case 2: }

One thing to remember is that it does not matter if the loop or decision structure actually visits the line of code. For example, the loop could execute zero or infinite times at runtime. Regardless of execution, the compiler will report an error if it finds any code it deems unreachable, in this case any statements immediately following a break, continue, or return statement.