Hello again! Here I come with simple java program, which generates random counting samples.Feel free to inspire yourself :).

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

public class InputStart {
	public static BufferedReader reader;
	static String again;

	/**
	 * @param args
	 */
	
	public static void main(String arg[]) throws IOException {
    reader = new BufferedReader(new InputStreamReader(System.in));
    
        do {
		Random random1 = new Random();
		int number1 = random1.nextInt(500);
		Random random2 = new Random();
		int number2 = random2.nextInt(500);
		
			System.out.println("Generate excercise? y / n.");
			String answer1 = reader.readLine();
			
			if (answer1.equals("y")) {
				System.out.println((number1) + "+" + (number2) + " is: ");
			     String result2 = reader.readLine();
			     int result1 = Integer.parseInt(result2);
			     
			     if (result1 == (number1)+(number2)) {
			    	 System.out.println("Good answer.");
			     }
			    	 else if (result1 != (number1)+(number2)) {
			    	 System.out.println("Wrong answer.");
                 }		
			}
			else System.exit(0);
			
			     System.out.println('\n' + "Press enter for continue...");
			     again = reader.readLine();
		}
					while(!again.equals("n"));
		            System.exit(0);
}
}