Difference Between String, StringBuffer, and StringBuilder in Java

In Java, working with strings efficiently can significantly impact performance. Java provides three key classes for string manipulation: String, StringBuffer, and StringBuilder. Each has unique properties, making them suitable for different use cases. Let’s explore the differences between them and when to use each.

 

String

String in Java is immutable, meaning once a string is created, it cannot be modified. Any modification results in a new object being created. This immutability can be inefficient if you’re performing many string operations.

String str = "Hello";
str = str + " World"; // Creates a new String object

Use Case: Use String when working with fixed or unchanging data, such as keys in a hashmap or string constants.

 

StringBuffer

StringBuffer is mutable and thread-safe, meaning it can be modified without creating new objects and is synchronized for use in multi-threaded environments. However, its thread-safety comes with a performance cost due to synchronization.

StringBuffer sb = new StringBuffer("Hello");
sb.append(" World"); // Modifies the existing object

Use Case: Use StringBuffer when working with strings in multi-threaded applications, where thread-safety is crucial.

 

StringBuilder

Like StringBuffer, StringBuilder is mutable but not thread-safe. It performs better than StringBuffer because it does not have synchronization overhead. However, it should be used only in single-threaded contexts.

StringBuilder sb = new StringBuilder("Hello");
sb.append(" World"); // Modifies the existing object efficiently

Use Case: Use StringBuilder for string manipulation in single-threaded applications where performance is a priority.

 

Conclusion:

In conclusion, choose String when immutability is needed, StringBuffer for thread-safe operations, and StringBuilder for high-performance string manipulations in single-threaded applications. Understanding these differences helps you write more efficient Java code tailored to your application’s needs.