Does `new String('abc')` Create a New String Object in Java's String Pool?

Java String Pool Duplication Confusion

Consider the following code snippet:

String first = "abc";
String second = new String("abc");

Using the new keyword creates a new String object. However, the question arises: does this new object reside in the regular heap or the String pool? And how many String objects end up in the pool?

String Pool Mechanism

The String pool serves as a cache, optimizing memory usage. When you declare a literal String like "abc," the compiler recognizes it and fetches the existing String object from the pool if one exists. Both s and p in the following example will reference the same String object:

String s = "abc";
String p = "abc";

Effect of new String()

However, creating a new String object using new String("abc") creates a separate object not stored in the pool. The pool stores a reference to the literal "abc" but not the copy generated with new.

Since String is immutable in Java, it's pointless to use new String("literal") as it incurs unnecessary overheads.

Interning Strings

Calling the intern() method on a String object adds it to the pool if it's not already present. This method returns a reference to the pooled String, whether it was already in the pool or not.

Conclusion

In essence, using the new keyword creates a separate String object outside the pool, even if the same literal string already exists in the pool. The String pool only stores references to literal strings, optimizing memory allocation. It's important to be aware of this behavior to avoid unnecessary object creation and promote efficient memory management.

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