2016a

А+Б. Ввод из файла. Вывод в файл

import java.io.*;
import java.util.*;

public class aplusb {
    public static void main(String[] args) throws IOException {
        Scanner in = new Scanner(new File("aplusb.in"));
        PrintWriter out = new PrintWriter(new File("aplusb.out"));
        int a = in.nextInt();
        int b = in.nextInt();
        out.println(a + b);
        in.close();
        out.close();
    }
}

Ввод двух чисел в строку

Scanner sc=new Scanner(System.in);
int num1=sc.nextInt();
int num2=sc.nextInt();

Ввод с клавиатуры

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) throws NumberFormatException, IOException {
		int a, b;
		
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		a = Integer.parseInt(br.readLine());
		b = Integer.parseInt(br.readLine());
		
		System.out.println(a+b);
	}

}

Функции

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
	
	public static void main(String[] args) throws NumberFormatException, IOException {
		int a, b, c;
		double d;
		
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		a = Integer.parseInt(br.readLine());
		b = Integer.parseInt(br.readLine());

		c = sum(a, b);
		
		d = mySqrt(b);
		
		System.out.println(c);
		System.out.println(d);
	}
	
	public static double mySqrt(int a) {
		return Math.sqrt(a);
	}

	public static int sum(int a, int b) {
		System.out.println("I really want to sleep");
		return a+b;
	}
	
	public static int max2(int a, int b) {
		if (a > b) {
			return a;
		} else {
			return b;
		}
	}
}