The Class String

String literals

Imagine that our program asks for the user’s full name, which we can represent as a string. Later in our program, we might want to use only the user’s first name or just the last name or, maybe, only the user’s initials. In this lesson, we explore how to work with strings.

Earlier, we used string literals and println statements to display lines of text. For example,
"Java is a programming language."
is a string literal. Actually, a string literal is an object that belongs to the class String. As such, it is a String object, or more simply a string, and it has the data type String. The class String is standard in Java and is a part of the Java Class Library within the package java.lang.

Creating String objects

We can declare the data type of a variable to be String much as we declare variables of other data types. We also can assign a string to a String variable. For example, we can write

String greeting = new String("Hello");

The new operator creates a new object of the indicated class type—String in this case—and String("Hello") initializes the object’s data portion. Here, the String object is initialized to "Hello".

Although we use the new operator to create an object of any class, we can create a String object more simply. Instead of the previous Java statement, we can write

String greeting = "Hello";

Thus, we can use a string literal as we would a primitive literal in an assignment statement. Java includes this simplification since strings are so prevalent in Java programs. We will see other classes later in this chapter that allow a similar initialization. For almost all classes, however, we must use the new operator to create a new object.