When should you use the 'new' keyword for Java Strings?

String Literals and New Keyword in Java Strings

In Java, the String class is a fundamental data type used to represent character sequences. However, there is a subtle difference between creating a new String object using the new keyword and directly assigning a literal string to a variable.

Using the new Keyword

The code snippet String s = new String("silly"); creates a new instance of the String class, with the literal "silly" as an argument. This operation allocates additional memory and creates a new object on the heap.

Directly Assigning a Literal

On the other hand, the assignment String s = "No longer silly"; directly assigns the literal value "No longer silly" to the variable s. Java automatically creates an anonymous String object and stores it in the variable, without the need to use the new keyword. This optimization avoids unnecessary memory allocation and object creation.

However, in the case of the CaseInsensitiveString class, which does not extend the String class, the direct assignment of a literal is not directly supported. To allow this, we have two options:

Option 1: Extend the String Class

We can extend the String class to create a CaseInsensitiveString class that inherits its behavior and allows direct assignment of literals. This is done by overriding the toString() and equals() methods to provide case-insensitive comparisons.

Option 2: Custom Constructor Overloads

Another approach is to overload the constructor of CaseInsensitiveString to accept literal arguments. This can be achieved by providing a constructor that takes a String argument and automatically initializes the s field.

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