Scanner next(Pattern) in Java

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

Syntax:

String java.util.Scanner.next(Pattern pattern)

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

Parameters: One parameter is required for this method.

pattern: the pattern to scan for.

Returns: the next token.

Throws:

1. NoSuchElementException - if no more tokens are available.

2. IllegalStateException - if this scanner is closed

Approach 1: When no exception

Java

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

public class Scannernext2 {
    public static void main(String[] args) {

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

        Pattern pattern = Pattern.compile("..llo");
        System.out.println(scanner.next(pattern));

        scanner.close();
    }
}

Output:

Hello

Approach 2: NoSuchElementException 

Java

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

public class Scannernext2 {
    public static void main(String[] args) {

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

        Pattern pattern = Pattern.compile("..llo");
        System.out.println(scanner.next(pattern));

        scanner.close();
    }
}

Output:

Exception in thread "main" java.util.NoSuchElementException
	at java.base/java.util.Scanner.throwFor(Scanner.java:937)
	at java.base/java.util.Scanner.next(Scanner.java:1594)
	

Approach 3: IllegalStateException

Java

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

public class Scannernext2 {
    public static void main(String[] args) {

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

        Pattern pattern = Pattern.compile("..llo");
        scanner.close();
        System.out.println(scanner.next(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.next(Scanner.java:1573)