1Z0-829 Exam Questions & Answers

The answer is C because the code fragment contains a syntax error in line 7, where the method display is declared without any parameter type. This causes a compilation error, as Java requires the parameter type to be specified for each method parameter. To fix this error, the parameter type should be added before the parameter name, such as string design. This will enable the code to compile and run without any errors.Reference:

Oracle Certified Professional: Java SE 17 Developer

Java SE 17 Developer

OCP Oracle Certified Professional Java SE 17 Developer Study Guide

Java Methods

The two code fragments that compile are B and E. These are the only ones that use the correct syntax for declaring and initializing a var variable. The var keyword is a reserved type name that allows the compiler to infer the type of the variable based on the initializer expression. However, the var variable must have an initializer, and the initializer must not be null or a lambda expression. Therefore, option A is invalid because it does not have an initializer, option C is invalid because it has a null initializer, and option D is invalid because it has a lambda expression as an initializer. Option B is valid because it has a String initializer, and option E is valid because it has an int initializer.

https://docs.oracle.com/en/java/javase/17/language/local-variable-type-inference.html

The code fragment in Option C invokes all callable objects in the workers set by using the ExecutorService's invokeAll() method. This method takes a collection of Callable objects and returns a list of Future objects representing the results of the tasks. The other options are incorrect because they either use the wrong method (invokeAny() or submit()) or have syntax errors (missing parentheses or semicolons).Reference:AbstractExecutorService (Java SE 17 & JDK 17) - Oracle

The code fragment uses the Collections.binarySearch method to search for the string ''e3'' in the list. The first search returns the index of the element, which is 2. The second search returns the index of the element, which is 0. The third search returns the index of the element, which is -4. The final result is 2.Reference:Collections (Java SE 17 & JDK 17) - Oracle

The code fragment is using the stream methods allMatch, anyMatch, noneMatch, and findFirst on a list of strings called specialDays.These methods are used to perform matching operations on the elements of a stream, such as checking if all, any, or none of the elements satisfy a given predicate, or finding the first element that matches a predicate1. The predicate in this case is that the string equals ''Labour'' or ''Halloween''. The output will be:

False: because not all of the elements in specialDays are equal to ''Labour'' or ''Halloween''.

true: because at least one of the elements in specialDays is equal to ''Labour'' or ''Halloween''.

true: because none of the elements in specialDays are equal to both ''Labour'' and ''Halloween''.

Optional[NewYear]: because the first element in specialDays that matches the predicate is ''NewYear'', and the findFirst method returns an Optional object that may or may not contain a non-null value2.