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Explain the concept of multithreading in Java

JavaMultithreadingConcurrencyThreads

Question

What is multithreading in Java? Explain thread lifecycle and synchronization.

Interview Answer

Multithreading enables concurrent task execution in a single process. In Java, you manage thread lifecycle, shared state safety, and coordination using synchronization primitives and concurrent utilities.

Explanation

Threads improve throughput and responsiveness, especially with I/O-heavy workflows. But shared mutable state introduces race conditions, deadlocks, and visibility issues unless synchronization or lock-free concurrent tools are used correctly.

Key Points

  • Thread lifecycle states define execution progression
  • Synchronization protects shared mutable state
  • Concurrency utilities simplify thread-safe design
  • Correctness is more important than raw parallelism

Common Mistakes

  • Using synchronized everywhere without contention strategy
  • Ignoring deadlock scenarios with nested locks
  • Sharing mutable objects across threads without protection

Likely Follow-Up Questions

  • Difference between synchronized and ReentrantLock?
  • What is volatile and when should it be used?
  • How do thread pools improve performance and control?

Interview Timing

Target speaking time: about 5 minutes.

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