Are Java Strings mutable?

Are Java Strings mutable?

• A. Yes
• B. No
• C. Sometimes
• D. Only if created with new

Answer: (B)

Strings in Java are immutable. That means once a String object is created, its characters cannot be changed. If you try to modify it, Java actually creates a new String object with the new contents. For example, concatenating strings or calling methods like replace or toUpperCase returns a new String rather than altering the original one. This behavior helps with safety when strings are shared across threads, allows Strings to be used reliably as keys in maps, and enables internal optimizations like string interning. Because immutability applies to every String regardless of how it was created, there’s no scenario where a String becomes mutable only if created with new. If you need a mutable sequence of characters, use StringBuilder or StringBuffer and convert to a String when you’re done.

Strings in Java are immutable. That means once a String object is created, its characters cannot be changed. If you try to modify it, Java actually creates a new String object with the new contents. For example, concatenating strings or calling methods like replace or toUpperCase returns a new String rather than altering the original one. This behavior helps with safety when strings are shared across threads, allows Strings to be used reliably as keys in maps, and enables internal optimizations like string interning.

Because immutability applies to every String regardless of how it was created, there’s no scenario where a String becomes mutable only if created with new. If you need a mutable sequence of characters, use StringBuilder or StringBuffer and convert to a String when you’re done.