Q 30 - Strings

[AmjustGettingStarted]

Dif btw String, String Builder & String Buffer?

[HARSHITH-MV]

✅ Difference Between String, StringBuilder, and StringBuffer in Java

Feature	String	StringBuilder	StringBuffer
Mutability	Immutable – cannot be changed	Mutable – can be changed	Mutable – can be changed
Thread Safety	Not thread-safe	Not thread-safe	Thread-safe (synchronized methods)
Performance	Slow for modifications	Faster than StringBuffer	Slower than StringBuilder
Synchronization	No	No	Yes
Use Case	Use when string doesn’t change	Use in single-threaded environments	Use in multi-threaded environments
Package	java.lang.String	java.lang.StringBuilder	java.lang.StringBuffer
Introduced In	Java 1.0	Java 1.5	Java 1.0

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🧠 Example:

➤ String (Immutable)

String s = "Hello";
s.concat(" World"); 
System.out.println(s); // Output: Hello

The original s is unchanged. A new string is created, but not stored.

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➤ StringBuilder (Mutable & Fast, Not Thread-Safe)

StringBuilder sb = new StringBuilder("Hello");
sb.append(" World");
System.out.println(sb); // Output: Hello World

Efficient for string operations in single-threaded environments.

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➤ StringBuffer (Mutable & Thread-Safe)

StringBuffer sbf = new StringBuffer("Hello");
sbf.append(" World");
System.out.println(sbf); // Output: Hello World

Use this in multi-threaded environments to avoid concurrency issues.

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🔁 Summary

When to Use
Use String when the string is fixed or changed rarely.
Use StringBuilder for fast string manipulation in single-threaded code.
Use StringBuffer when multiple threads modify the string and thread safety is required.