What is String Interning?

Difficulty: 6/10

memory management, performance optimization, string pooling

String Interning

String interning is a mechanism where identical string values can share a single canonical instance. In Java, string literals are placed in the string pool, and explicit interning can request the canonical pooled representation. This can reduce duplicate string objects.

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1
Interning can reduce memory usage when the same strings occur repeatedly.
2
It can make identity comparisons meaningful for interned references, although content comparison should normally use equals().
3
Interning has overhead, so it should not be applied indiscriminately to high-cardinality data.
4
Immutable strings are important because shared instances must not be modifiable.

Scenario Questions

0-2 years experience

2-5 years experience

1Your team added a feature that stores user‑entered tags in a global pool using `String.intern()`. After deployment you notice increased GC pauses. What could be causing this, and how would you investigate?

What is String Interning?

String Interning

Scenario Questions

Follow-up Questions