Читать книгу OCP Oracle Certified Professional Java SE 17 Developer Study Guide - Jeanne Boyarsky - Страница 213

This chapter presented how to make intelligent decisions in Java. We covered basic decision-making constructs such as if, else, and switch statements and showed how to use them to change the path of the process at runtime. We also presented newer features in the Java language, including pattern matching and switch expressions, both designed to reduce boilerplate code.

We then moved our discussion to repetition control structures, starting with while and do/while loops. We showed how to use them to create processes that loop multiple times and also showed how it is important to make sure they eventually terminate. Remember that most of these structures require the evaluation of a particular boolean expression to complete.

Next, we covered the extremely convenient repetition control structures: the for and for-each loops. While their syntax is more complex than the traditional while or do/while loops, they are extremely useful in everyday coding and allow you to create complex expressions in a single line of code. With a for-each loop, you don't need to explicitly write a boolean expression, since the compiler builds one for you. For clarity, we referred to an enhanced for loop as a for-each loop, but syntactically both are written using the for keyword.

We concluded this chapter by discussing advanced control options and how flow can be enhanced through nested loops coupled with break, continue, and return statements. Be wary of questions on the exam that use nested loops, especially ones with labels, and verify that they are being used correctly.

This chapter is especially important because at least one component of this chapter will likely appear in every exam question with sample code. Many of the questions on the exam focus on proper syntactic use of the structures, as they will be a large source of questions that end in “Does not compile.” You should be able to answer all of the review questions correctly or fully understand those that you answered incorrectly before moving on to later chapters.