Читать книгу OCP Oracle Certified Professional Java SE 17 Developer Study Guide - Jeanne Boyarsky - Страница 214

Understand if and else decision control statements. The if and else statements come up frequently throughout the exam in questions unrelated to decision control, so make sure you fully understand these basic building blocks of Java.

Apply pattern matching and flow scoping. Pattern matching can be used to reduce boilerplate code involving an if statement, instanceof operator, and cast operation using a pattern variable. It can also include a pattern or filter after the pattern variable declaration. Pattern matching uses flow scoping in which the pattern variable is in scope as long as the compiler can definitively determine its type.

Understand switch statements and their proper usage. You should be able to spot a poorly formed switch statement on the exam. The switch value and data type should be compatible with the case statements, and the values for the case statements must evaluate to compile-time constants. Finally, at runtime, a switch statement branches to the first matching case, or default if there is no match, or exits entirely if there is no match and no default branch. The process then continues into any proceeding case or default statements until a break or return statement is reached.

Use switch expressions correctly. Discern the differences between switch expressions and switch statements. Understand how to write switch expressions correctly, including proper use of semicolons, writing case expressions and blocks that yield a consistent value, and making sure all possible values of the switch variable are handled by the switch expression.

Write while loops. Know the syntactical structure of all while and do/while loops. In particular, know when to use one versus the other.

Be able to use for loops. You should be familiar with for and for-each loops and know how to write and evaluate them. Each loop has its own special properties and structures. You should know how to use for-each loops to iterate over lists and arrays.

Understand how break, continue, and return can change flow control. Know how to change the flow control within a statement by applying a break, continue, or return statement. Also know which control statements can accept break statements and which can accept continue statements. Finally, you should understand how these statements work inside embedded loops or switch statements.