1z0-829 Java SE 17 Developer Questions and Answers

The answer is D because the code fragment uses the Stream API to create two streams, s1 and s2, and then concatenates them using the concat() method. The resulting stream is then processed in parallel using the parallel() method, and the distinct() method is used to remove duplicate elements. Finally, the forEach() method is used to print the elements of the resulting stream to the console. Since the order of elements in a parallel stream is unpredictable, the output could be any of the options given, but option D is the most likely. References:

• Oracle Certified Professional: Java SE 17 Developer
• Java SE 17 Developer
• OCP Oracle Certified Professional Java SE 17 Developer Study Guide
• Parallelizing Streams

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. References:

• Oracle Certified Professional: Java SE 17 Developer
• Java SE 17 Developer
• OCP Oracle Certified Professional Java SE 17 Developer Study Guide
• Java Methods

The code fragment will fail to compile because the class name and the constructor name do not match. The class name is Furniture, but the constructor name is Wtable. This will cause a syntax error. The correct way to define a constructor is to use the same name as the class name. Therefore, the code fragment should change the constructor name to Furniture or change the class name to Wtable.

The code will compile if the regNo variable is made public. This is because the regNo variable is being accessed in the main method of the App class, which is outside the scope of the Product class. Making the regNo variable public will allow it to be accessed from outside the class. References: https://education.oracle.com/products/trackp_OCPJSE17, https://mylearn.oracle.com/ou/learning-path/java-se-17-developer/99487, https://docs.oracle.com/javase/tutorial/java/javaOO/accesscontrol.html

The code fragment is using the bitwise operators & (AND), | (OR), and ^ (XOR) to perform operations on the binary representations of the integer values. The & operator returns a 1 in each bit position where both operands have a 1, the | operator returns a 1 in each bit position where either operand has a 1, and the ^ operator returns a 1 in each bit position where only one operand has a 1. The binary representations of the integer values are as follows:

• 1000 = 1111101000
• 100 = 1100100
• 101 = 1100101

The code fragment performs the following operations:

• x = x ^ y; // x becomes 1111010101, which is 1001 in decimal
• y = x ^ y; // y becomes 1100100, which is 100 in decimal
• x = x ^ y; // x becomes 1100101, which is 101 in decimal

The code fragment then prints out the values of x, y, and z, which are 1001, 100, and 1000 respectively. Therefore, option D is correct.

The answer is E because the code fragment creates a new Pet object with the name “Dog” and assigns it to the variable p. Then, it assigns p to p1. Next, it changes the name of p1 to “Cat”. Then, it assigns p1 to p. Finally, it sets p to null and prints the name of p and p1. The output will be “Cat” and “null” because p is set to null and p1 still points to the Pet object with the name “Cat”.

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 creates two threads, t1 and t2, and starts them. The threads will print their names and the value of the Atomic Integer object, x, which is initially set to 1. The threads will then increment the value of x and print their names and the new value of x. Since the threads are started at the same time, the output will be in random order. However, the final output will always be t1 : 1 : t2: 1 : t1 : 2 : t2: 2: References: AtomicInteger (Java SE 17 & JDK 17) - Oracle

The code is defining an enum class called Forecast with three values: SUNNY, CLOUDY, and RAINY. The toString() method is overridden to always return “SNOWY”. In the main method, the ordinal value of SUNNY is printed, which is 0, followed by the value of CLOUDY converted to uppercase, which is “CLOUDY”. However, since the toString() method of Forecast returns “SNOWY” regardless of the actual value, the output will be “0 SNOWY”. References: Enum (Java SE 17 & JDK 17), Enum.EnumDesc (Java SE 17 & JDK 17)

The answer is B because the code fragment contains a logical error that causes a MissingResourceException at runtime. The code fragment tries to load a resource bundle with the base name “Captions.properties” and the locale “en_US”. However, there is no such resource bundle available in the classpath. The available resource bundles are:

• Captions.properties
• Captions_en.properties
• Captions_US.properties
• Captions_en_US.properties

The ResourceBundle class follows a fallback mechanism to find the best matching resource bundle for a given locale. It first tries to find the resource bundle with the exact locale, then it tries to find the resource bundle with the same language and script, then it tries to find the resource bundle with the same language, and finally it tries to find the default resource bundle with no locale. If none of these resource bundles are found, it throws a MissingResourceException.

In this case, the code fragment is looking for a resource bundle with the base name “Captions.properties” and the locale “en_US”. The ResourceBundle class will try to find the following resource bundles in order:

• Captions.properties_en_US
• Captions.properties_en
• Captions.properties

However, none of these resource bundles exist in the classpath. Therefore, the ResourceBundle class will throw a MissingResourceException.

To fix this error, the code fragment should use the correct base name of the resource bundle family, which is “Captions” without the “.properties” extension. For example:

ResourceBundle captions = ResourceBundle.getBundle(“Captions”, currentLocale);

This will load the appropriate resource bundle for the current locale, which is “Captions_en_US.properties” in this case. References:

• Oracle Certified Professional: Java SE 17 Developer
• Java SE 17 Developer
• OCP Oracle Certified Professional Java SE 17 Developer Study Guide
• ResourceBundle (Java Platform SE 8 )
• About the ResourceBundle Class (The Java™ Tutorials > Internationalization)

The code fragment will fail to compile because the play method in the Dog class is declared as private, which means that it cannot be accessed from outside the class. The main method is trying to call the play method on a Dog object, which is not allowed. Therefore, the code fragment will produce a compilation error.

The code given is an interface and a class that implements the interface. The interface has three methods, m1(), m2(), and m3(). The class has one method, m1(). The only two method invocations that will execute are D and E. D is a call to the m2() method in the class, and E is a call to the m3() method in the interface. References: https://education.oracle.com/products/trackp_OCPJSE17,  3, 4, 5