The String class is immutable. What does this mean?

Immutable refers to an object whose state cannot be changed after it is created. This means that once an instance of an immutable class, like String class, is initialized with a specific value, it cannot be modified. Instead, any operation that seems to change the value of a String object will create a new String object with the modified value, leaving the original object unchanged.

Immutability is an important concept in programming languages, and it offers several benefits when it comes to the String class: 1. Security: Since the content of a String object cannot be changed after it is created, it provides a higher level of security by preventing the manipulation of sensitive data, such as passwords, usernames, and file paths. 2. Thread Safety: Immutable objects are inherently thread-safe as they cannot be modified by multiple threads concurrently. This simplifies the handling of multithreading and reduces the risk of bugs. 3. Performance: Immutability allows for more efficient memory usage, as multiple variables can reference the same immutable String object instead of creating multiple copies of the same value. Additionally, some operations like string concatenation are more efficient when using other mutable classes like StringBuilder or StringBuffer.

Let's see an example of immutability in the String class: ```java String originalString = "Hello, World!"; String uppercaseString = originalString.toUpperCase(); System.out.println("Original String: " + originalString); // Output: Hello, World! System.out.println("Uppercase String: " + uppercaseString); // Output: HELLO, WORLD! ``` In the above example, the originalString is initialized with the value "Hello, World!". When we call the toUpperCase() method, it does not change the content of the originalString. Instead, it creates a new String object called uppercaseString with the modified value "HELLO, WORLD!". The originalString remains unchanged, which demonstrates the immutability of the String class.