Java Scanner useDelimiter()

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In this guide, you will learn about the Scanner useDelimiter() method in Java programming and how to use it with an example.

1. Scanner useDelimiter() Method Overview

Definition:

The useDelimiter() method of the Scanner class in Java is used to set the delimiting pattern of the scanner which separates tokens in the input. It provides a way to instruct the scanner to recognize custom delimiters apart from whitespace, which is the default delimiter.

Syntax:

public Scanner useDelimiter(String pattern) 
public Scanner useDelimiter(Pattern pattern)

Parameters:

- pattern: A string specifying the delimiter pattern. This can be a regular expression.

- Alternatively, you can use the Pattern class to specify the delimiter.

Key Points:

- The useDelimiter() method returns a Scanner object, allowing for method chaining.

- The scanner will use the provided delimiter until it's changed again.

- If no delimiter is set, the default is whitespace.

- The delimiter does not need to be a single character; it can be a regular expression to match more complex patterns.

2. Scanner useDelimiter() Method Example

import java.util.Scanner;

public class ScannerExample {
    public static void main(String[] args) {
        String data = "apple,orange-banana;grape";
        Scanner scanner = new Scanner(data).useDelimiter("[,-;]+");

        while(scanner.hasNext()) {
            String fruit = scanner.next();
            System.out.println(fruit);
        }
    }
}

Output:

apple
orange
banana
grape

Explanation:

In this example, we have a string of fruit names separated by different delimiters: comma, hyphen, and semicolon. We use the useDelimiter() method to specify a regular expression that matches any of these delimiters. The scanner then reads and prints each fruit name separately.