System 창에서 입력 받기

import java.util.Scanner;

public class Main {
	
	public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in);
		System.out.print("정수를 입력하세요 : ");
		int i = sc.nextInt();
		System.out.println("입력된 정수는 : " + i + "입니다.");
		sc.close();
	}
}

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

public class Main {
	
	public static void main(String[] args) {
		
		File file = new File("input.txt");
		try {
			Scanner sc = new Scanner(file);
			while (sc.hasNextInt()) {
				System.out.println(sc.nextInt());
			}
			sc.close();
		} catch (FileNotFoundException e) {
			System.out.println("파일을 읽어오는 동안에 오류가 발생하였습니다.");
		}
	}
}