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Collections · medium

24. HashMap

Key-value mapping.

1 min read2 questionsup to 50 XPtopic 24/50

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HashMap stores data in pairs. It allows null keys and values but is not thread-safe.

How to study this topic

  1. 1. Read the explanation once end to end, skipping the code.
  2. 2. Re-read the code snippets and say out loud what each line does.
  3. 3. Answer the quiz without scrolling back — that is the real check.
  4. 4. Read every explanation, even for the answers you got right.

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Check your understanding

  1. 1. How to get a value?

  2. 2. Unique keys required?

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