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LetsGit.IT/Categories/Java
Javaeasy

JDK vs JRE vs JVM - what is each?

Tags
#jvm#jre#jdk#basics
Back to categoryPractice quiz

Answer

JVM runs Java bytecode. JRE is the runtime environment (JVM + standard libraries) needed to run apps. JDK is the development kit (JRE + compiler and tools) needed to build apps.

Advanced answer

Deep dive

Expanding on the short answer — what usually matters in practice:

  • Context (tags): jvm, jre, jdk, basics
  • JVM: memory (heap/stack), GC, and what drives latency.
  • Contracts: equals/hashCode/toString, mutability and consequences.
  • Performance: boxing, allocations, collections, inlining.
  • Explain the "why", not just the "what" (intuition + consequences).
  • Trade-offs: what you gain/lose (time, memory, complexity, risk).
  • Edge cases: empty inputs, large inputs, invalid inputs, concurrency.

Examples

A tiny example (an explanation template):

// Example: discuss trade-offs for "jdk-vs-jre-vs-jvm---what-is-each?"
function explain() {
  // Start from the core idea:
  // JVM runs Java bytecode. JRE is the runtime environment (JVM + standard libraries) needed t
}

Common pitfalls

  • Too generic: no concrete trade-offs or examples.
  • Mixing average-case and worst-case (e.g., complexity).
  • Ignoring constraints: memory, concurrency, network/disk costs.

Interview follow-ups

  • When would you choose an alternative and why?
  • What production issues show up and how do you diagnose them?
  • How would you test edge cases?

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