Scanner hasNext(Pattern) in Java

hasNext(Pattern): This method is available in java.util.Scanner class of Java.

Syntax:

boolean java.util.Scanner.hasNext(Pattern pattern)

This method takes one argument. This method returns true if the next complete token matches the specified pattern.

Parameters: One parameter is required for this method.

pattern: the pattern to scan for.

Returns: true if and only if this scanner has another token matching the specified pattern.

Throws:

IllegalStateException - if this scanner is closed

Approach 1: When no exception

Java

import java.util.Scanner;
import java.util.regex.Pattern;

public class ScannerhasNext2 {
    public static void main(String[] args) {

        String source = "Hello World";
        Scanner scanner = new Scanner(source);

        Pattern pattern = Pattern.compile("[a-z]");
        System.out.println(scanner.hasNext(pattern));

        scanner.close();
    }
}

Output:

false

Approach 2: IllegalStateException 

Java

import java.util.Scanner;
import java.util.regex.Pattern;

public class ScannerhasNext2 {
    public static void main(String[] args) {

        String source = "Hello World";
        Scanner scanner = new Scanner(source);

        Pattern pattern = Pattern.compile("[a-z]");
        scanner.close();
        System.out.println(scanner.hasNext(pattern));

    }
}

Output:

Exception in thread "main" java.lang.IllegalStateException: Scanner closed
	at java.base/java.util.Scanner.ensureOpen(Scanner.java:1150)
	at java.base/java.util.Scanner.hasNext(Scanner.java:1540)