Java String matches()

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

    // a regex pattern for
    // four letter string that starts with 'J' and end with 'a'
    String regex = "^J..a$";

    System.out.println("Java".matches(regex));

  }
}

// Output: true

Syntax of matches()

The syntax of the string matches() method is:

string.matches(String regex)

Here, string is an object of the String class.

matches() Parameters

The matches() method takes a single parameter.

• regex - a regular expression

matches() Return Value

• returns true if the regex matches the string
• returns false if the regex doesn't match the string

Example 1: Java matches()

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

    // a regex pattern for
    // five letter string that starts with 'a' and end with 's'
    String regex = "^a...s$";

    System.out.println("abs".matches(regex)); // false
    System.out.println("alias".matches(regex)); // true
    System.out.println("an abacus".matches(regex)); // false

    System.out.println("abyss".matches(regex)); // true
  }
}

Here, "^a...s$" is a regex, which means a 5 letter string that starts with a and ends with s.

Example 2: Check for Numbers

// check whether a string contains only numbers

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

    // a search pattern for only numbers
    String regex = "^[0-9]+$";

    System.out.println("123a".matches(regex)); // false
    System.out.println("98416".matches(regex)); // true

    System.out.println("98 41".matches(regex)); // false
  }
}

Here, "^[0-9]+$" is a regex, which means only digits.