How has string pool and interning changed in recent Java versions?

The Java String Pool, also known as the intern pool, is a special storage area in Java heap memory where String literals are stored. The concept of string interning allows for efficient memory management by reusing immutable String objects. Over recent Java versions, the implementation and performance of string interning have seen some enhancements, leading to better memory optimization and faster access.

In earlier versions of Java, every time a new String was created, a new object was allocated in memory, even if it contained the same characters as an existing String. With the introduction of the String Pool, Java began to store String literals in a shared pool, thus limiting the creation of duplicate String objects. In recent versions, especially with improvements made in Java 9 and above, optimizations related to the String Pool have further enhanced performance and reduced memory footprint.

For example, Java now leverages a variety of optimizations in string handling, which can significantly impact applications with large numbers of String operations.

        String str1 = "Hello";
        String str2 = "Hello";
        
        // Both str1 and str2 refer to the same object in the String Pool
        if (str1 == str2) { 
            System.out.println("Both strings point to the same object."); // This will print
        }