String

String Creation and Memory

String Initialization

In Java, String is a final class, meaning it cannot be extended. Strings are objects and can be created in two ways:

String Literal (Recommended): Stored in the String Constant Pool, reuses references for identical strings.

String str = "Hello";  // Reuses reference

- String Object: Stored in Heap Memory, creates a new object even if identical string exists.

String str = new String("Hello");

String Immutability and Garbage Collection

Strings are immutable. Modifying a string creates a new object, leaving the original eligible for garbage collection if unreferenced.

String str = "Hello";
str = "World"; // "Hello" becomes eligible for garbage collection
System.out.println(str); // Outputs: World

Mutable Strings

StringBuilder: Faster, not thread-safe.
StringBuffer: Thread-safe, slower due to synchronization.

Use StringBuilder for performance in single-threaded scenarios and StringBuffer for thread-safe operations.

StringBuilder sb = new StringBuilder("Hello");
sb.append(" World"); // Modifies the original object
System.out.println(sb); // Outputs: Hello World

Use these classes in loops or for frequent string modifications to avoid creating multiple immutable objects.

StringBuilder sb = new StringBuilder();
for (int i = 0; i < 100000; i++) {
    sb.append(i); // Efficient thanks to mutable nature. If strings were used, it would create 100,000 objects.
}
System.out.println(sb.toString());

String Joiner

Joining Strings

Joins strings with a delimiter, prefix, and suffix.

import java.util.StringJoiner;

StringJoiner joiner = new StringJoiner(", ", "[", "]");
joiner.add("Apple").add("Banana").add("Orange");
System.out.println(joiner); // Outputs: [Apple, Banana, Orange]