Do String Literals Ever Get Garbage Collected? Exploring Nuances of String Interning and Class Unloading.

Garbage Collection of String Literals

Question:

String literals are generally considered to be interned and hence not susceptible to garbage collection. However, confusion arises when exploring the nuances of string concatenation, String class caching, and class unloading. To clarify, let's delve into the following questions:

1. Will a string defined as a compile-time literal ("java") ever be garbage collected?
2. How does the intern method influence garbage collection behavior?
3. Is it true that literals are only garbage collected when the String class is unloaded?

Answer:

1. Garbage Collection of Compile-Time Literals:

String literals, defined at compile time, live as long as the class loader that loaded the code containing those literals. As long as the classes using the literals remain loaded, the String objects representing them will not be garbage collected. However, if the class loader is destroyed, the literals may be subject to garbage collection.

2. intern Method and Garbage Collection:

Calling the intern method on a string returns the same object representing the string literal. As such, the interned string has the same lifespan as the literal itself. However, strings created using new that are not identical to string literals can be garbage collected if they become unreachable.

3. Class Unloading and String Literals:

It is incorrect to claim that literals are only garbage collected when the String class is unloaded. Java does not unload its core classes, including the String class. String literals are retained as long as the code referencing them remains active.

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