Length

A Java String object may be null—but if it exists, it has zero or more characters. This character count is its length. With length() we get this number.

In a loop over characters, we can proceed from 0 to length() minus 1. A string's length has many uses in programs. We can take the length of a literal directly.

Example

We use string literals. These are specified directly in the program. Then with the plus operator, we combine (concatenate) these strings.

public class Program {
    public static void main(String[] args) {

        // Create strings with literals.
        String value1 = "Java";
        String value2 = "Programmer";

        // Concatenate strings.
        String value3 = value1 + " " + value2;

        // Print string.
        System.out.println(value3);

        // Get string lengths.
        int length1 = value1.length();
        int length2 = value2.length();
        int length3 = value3.length();

        // Print lengths.
        System.out.println(length1);
        System.out.println(length2);
        System.out.println(length3);
    }
}
Java Programmer
4
10
15

Literal length

This program uses a literal "abc" and immediately takes the length of that literal. This returns the number 3. This is valid Java syntax.

public class Program {
    public static void main(String[] args) {

        // Take the length of a literal directly.
        int length = "abc".length();
        System.out.println(length);
    }
}
3

Some notes

When using string literals in a program, we want to avoid confusing code. It is clearer to use length() on a literal than encode the magic value 3 in a program.

The length() method is called on a String object. The String must not be null. Length returns the character count in the string data.