1Z0-819 Cheat Sheet 2026

The 30 highest-yield 1Z0-819 facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Which foundational principle is MOST important for success in the Oracle Java SE 11 Developer profession? → Commitment to continuous learning, ethical practice, and quality outcomes
2. What is the purpose of the 'uses' directive in a module-info.java? → It declares that the module may discover service providers via ServiceLoader
3. What role does peer review play in the 1Z0-819 design process? → It provides independent verification, catches errors, and enhances overall quality
4. Which class provides buffered character-based reading with a `readLine()` method? → BufferedReader
5. Which of the following correctly declares a type parameter with multiple bounds? → public class MyClass>
6. Which annotation was introduced in Java 9 to indicate that a module exports a package for use only by specific other modules? → None — this is a module-info.java keyword, not an annotation
7. Which `Connection` transaction isolation level offers the strongest consistency guarantee, preventing dirty reads, non-repeatable reads, and phantom reads? → TRANSACTION_SERIALIZABLE
8. In Java, what is a 'has-a' relationship implemented through? → Composition (field reference)
9. When a 1Z0-819 professional encounters an unexpected result during a technical procedure, the FIRST action should be to: → Stop, assess the situation, and determine whether to proceed or seek guidance
10. What role does collaboration play in jdbc for 1Z0-819 professionals? → It enhances outcomes through diverse perspectives and shared expertise
11. Which approach is recommended for troubleshooting modules system issues? → Use systematic isolation and testing methods
12. What is the time complexity of `LinkedList.get(index)` in Java? → O(n)
13. Which collector can be used to produce a Map> from a stream? → Collectors.partitioningBy()
14. What is the default value of an instance variable of type `boolean` in Java? → false
15. What is the result of `Duration.between(LocalTime.of(10,0), LocalTime.of(9,0)).toHours()`? → -1
16. What is the output of `System.out.printf("%05.2f", 3.7)` ? → "03.70"
17. Which functional interface should you use when a lambda takes two arguments of the same type and returns a result of the same type? → BinaryOperator
18. Which tool is used to link a set of modules into a custom runtime image in Java 11? → jlink
19. Which method on `Predicate` returns a new Predicate that is the logical negation of the original? → negate()
20. Which command-line option adds a module to the set of root modules resolved by the module system? → --add-modules
21. Which `Map` method was added in Java 8 and computes a new value only if the key is absent? → computeIfAbsent()
22. What is the primary benefit of version control in stream api for 1Z0-819? → It tracks changes and enables collaboration
23. What happens when you place a non-modular JAR on the module path? → It becomes an automatic module with a name derived from the JAR filename
24. Which file defines a module in Java? → module-info.java
25. The @FunctionalInterface annotation is declared with which retention policy? → RUNTIME
26. Which `Connection` method creates a `Statement` object for executing static SQL? → connection.createStatement()
27. What is the module name for the foundational Java SE module that all other modules implicitly depend on? → java.base
28. Which method creates all missing parent directories for a given path in one call? → Files.createDirectories(path)
29. What happens if an exception is not caught? → The JVM handles it and may terminate the program
30. Which professional attribute is most valued in jdbc within the 1Z0-819 field? → Accountability and commitment to standards