Java Scanner.hasNext() method

A Scanner breaks its input into tokens using a delimiter pattern, which matches whitespace by default.
The hasNext() method checks if the Scanner has another token in its input.

/**
 * @author lautturi.com 
 * Java example: reading file using Scanner in java
 */

import java.io.File;
import java.io.FileNotFoundException;
import java.util.*;

public class Lautturi {

	public static void main(String[] args) throws FileNotFoundException {
		Scanner scanner = new Scanner(new File("test.txt"));
		StringBuilder sb = new StringBuilder();

		while (scanner.hasNext()) {
			sb.append(scanner.nextLine()).append("\n");
		}

		System.out.println("File text :" + sb);
	}
}

The hasNext() method determines whether the input (file, string, keyboard and other input streams) has the next input item.

Scanner sc = new Scanner(new File("text.txt"));
System.out.println(sc.hasNext());

If test.txt is empty (space, tab, enter), the output result is false; otherwise true.

When the input is the keyboard, the method is blocked:
It will always wait for keyboard input

Scanner sc = new Scanner(System.in);
while(sc.hasNext()) {
    System.out.println("Input from keyboard:" + sc.next());
}