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Oracle Java SE 21 Developer Professional : 1z0-830

1z0-830 actual test
  • Exam Code: 1z0-830
  • Exam Name: Java SE 21 Developer Professional
  • Updated: Aug 14, 2026
  • Q & A: 85 Questions and Answers
  • PDF Demo
  • PC Test Engine
  • Online Test Engine
  • Total Price: $59.99  

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Oracle 1z0-830 Exam Syllabus Topics:

SectionObjectives
Concurrency and Multithreading- Thread management
  • 1. Thread lifecycle and synchronization
    • 2. Virtual threads and structured concurrency concepts
      Exception Handling and Debugging- Error handling mechanisms
      • 1. Try-with-resources
        • 2. Checked vs unchecked exceptions
          Input/Output and File Handling- NIO and file operations
          • 1. Serialization basics
            • 2. File, Path, and Streams APIs
              Core APIs- Java standard library usage
              • 1. Collections Framework
                • 2. Date and Time API
                  • 3. Streams and functional programming
                    Database Connectivity (JDBC)- Database interaction
                    • 1. SQL execution and result handling
                      • 2. JDBC API usage
                        Java Language Fundamentals- Java syntax and language structure
                        • 1. Control flow statements
                          • 2. Data types, variables, and operators
                            Object-Oriented Programming- Core OOP principles
                            • 1. Encapsulation, inheritance, polymorphism
                              • 2. Abstract classes and interfaces
                                Advanced Java Features (Java SE 21)- Modern language features
                                • 1. Pattern matching for switch
                                  • 2. Virtual threads (Project Loom)
                                    • 3. Records and record patterns
                                      • 4. Sealed classes

                                        Oracle Java SE 21 Developer Professional Sample Questions:

                                        1. Which of the following can be the body of a lambda expression?

                                        A) Two statements
                                        B) Two expressions
                                        C) A statement block
                                        D) An expression and a statement
                                        E) None of the above


                                        2. Given:
                                        java
                                        Object myVar = 0;
                                        String print = switch (myVar) {
                                        case int i -> "integer";
                                        case long l -> "long";
                                        case String s -> "string";
                                        default -> "";
                                        };
                                        System.out.println(print);
                                        What is printed?

                                        A) long
                                        B) Compilation fails.
                                        C) nothing
                                        D) integer
                                        E) string
                                        F) It throws an exception at runtime.


                                        3. Consider the following methods to load an implementation of MyService using ServiceLoader. Which of the methods are correct? (Choose all that apply)

                                        A) MyService service = ServiceLoader.services(MyService.class).getFirstInstance();
                                        B) MyService service = ServiceLoader.load(MyService.class).findFirst().get();
                                        C) MyService service = ServiceLoader.getService(MyService.class);
                                        D) MyService service = ServiceLoader.load(MyService.class).iterator().next();


                                        4. Given:
                                        var cabarets = new TreeMap<>();
                                        cabarets.put(1, "Moulin Rouge");
                                        cabarets.put(2, "Crazy Horse");
                                        cabarets.put(3, "Paradis Latin");
                                        cabarets.put(4, "Le Lido");
                                        cabarets.put(5, "Folies Bergere");
                                        System.out.println(cabarets.subMap(2, true, 5, false));
                                        What is printed?

                                        A) Compilation fails.
                                        B) CopyEdit{2=Crazy Horse, 3=Paradis Latin, 4=Le Lido, 5=Folies Bergere}
                                        C) {2=Crazy Horse, 3=Paradis Latin, 4=Le Lido}
                                        D) An exception is thrown at runtime.
                                        E) {}


                                        5. Given:
                                        java
                                        var lyrics = """
                                        Quand il me prend dans ses bras
                                        Qu'il me parle tout bas
                                        Je vois la vie en rose
                                        """;
                                        for ( int i = 0, int j = 3; i < j; i++ ) {
                                        System.out.println( lyrics.lines()
                                        .toList()
                                        .get( i ) );
                                        }
                                        What is printed?

                                        A) vbnet
                                        Quand il me prend dans ses bras
                                        Qu'il me parle tout bas
                                        Je vois la vie en rose
                                        B) Nothing
                                        C) Compilation fails.
                                        D) An exception is thrown at runtime.


                                        Solutions:

                                        Question # 1
                                        Answer: C
                                        Question # 2
                                        Answer: B
                                        Question # 3
                                        Answer: B,D
                                        Question # 4
                                        Answer: C
                                        Question # 5
                                        Answer: C

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