Interview Q&A / Java
Java interview questions
Collections, the JVM, strings, exceptions and threads, the backbone of most campus placement rounds.
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- How does HashMap work internally in Java?
HashMap stores entries in an array of buckets. It hashes the key, picks a bucket from that hash, and stores the entry there; keys that land in the same bucket form a linked list, which since Java 8 turns into a red-black tree when it gets long. When the map is 75% full it doubles the array and redistributes entries.
AdvancedIn-depth4 min read - What are strong, soft, weak and phantom references in Java?
A strong reference prevents collection. A soft reference is cleared only when memory is short, a weak reference is cleared at the next collection once no strong refs remain, and a phantom reference is used to know when an object has been reclaimed.
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