Java .length()

In Java, the .length() method returns the length or number of characters in a string. It’s a built-in method that comes with the String class. This is particularly useful while validating user input, manipulating text, or working with dynamic content.

Syntax

string.length()

Parameters:

The .length() method requires no parameters.

Return value:

The .length() method returns a string’s length or number of characters.

Example 1: Basic Usage of .length()

This example uses the .length() method to get the length of a string:

class Example {
  public static void main(String[] args) {
    String greetings = "Hello, Code Ninja!";
    System.out.println(greetings.length());
  }
}

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Here is the output:

18

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Example 2: Using .length() on an Empty String

This example uses the .length() method to get the length of an empty string:

public class EmptyString {
  public static void main(String[] args) {
    String empty = "";
    System.out.println("Length of the empty string: " + empty.length());
  }
}

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Here is the output:

Length of the empty string: 0

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Example 3: Using .length() in Conditional Statements

This example uses the .length() method in conditional statements to check if a password is at least 8 characters long:

public class PasswordCheck {
  public static void main(String[] args) {
    String password = "pass123";
    if (password.length() < 8) {
      System.out.println("Password is too short.");
    } else {
      System.out.println("Password length is acceptable.");
    }
  }
}

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Here is the output:

Password is too short.

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Frequently Asked Questions

1. Does .length() count spaces and special characters?

Yes, .length() counts all characters, including whitespaces, symbols, and punctuations.

2. What happens if I call .length() on null?

You will get a NullPointerException. Always ensure the string is not null before calling .length().

3. Can I use .length() with other data types like int or char?

No, .length() is only applicable to strings.