SCJP Study Guide 2026
Everything you need to pass the SCJP exam in one place: the exam format, every topic to study, real practice questions with explanations, flashcards, and full-length practice tests. Free, no sign-up needed.
📋 SCJP Exam Format at a Glance
📚 SCJP Topics to Study (21)
✍️ Sample SCJP Questions & Answers
1. What is the difference between `Iterator` and `ListIterator` in Java?
`ListIterator` extends `Iterator` with the ability to traverse a list in both forward and backward directions and also supports `add()` and `set()`.
2. What is a race condition in Java concurrency?
A race condition occurs when the program's outcome depends on the non-deterministic ordering of unsynchronized thread operations.
3. In Java, can a class implement more than one interface?
A Java class can implement multiple interfaces by listing them with commas: `class Foo implements A, B, C`.
4. What happens when `Thread.start()` is called more than once on the same Thread object?
Once a thread has been started and has terminated, calling `start()` again on the same Thread object throws `IllegalThreadStateException`.
5. Which statement about Java interfaces is correct for SCJP?
All fields declared in an interface are implicitly `public static final` (constants).
6. Which Java I/O class should be used to write primitive data types (int, double, boolean) to a stream?
`DataOutputStream` provides methods like `writeInt()`, `writeDouble()`, and `writeBoolean()` for writing primitive data types in a portable binary format.