public static int[] resultDice = {0, 0, 0, 0, 0, 0, 0};
public static int numberOfUserRolls = 0;

public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    System.out.println("Please enter the number of rolls. But don't forget, if you enter a number smaller than 20, you will receive an error!");
    numberOfUserRolls = scanner.nextInt();

    rollDice();

}

public static void rollDice() {
    int dice = 0;

    for (int i = 0; i < numberOfUserRolls; i++) {

        Random rnd = new Random();

        dice = 1 + rnd.nextInt((6 - 1) + 1);
        resultDice[dice] = resultDice[dice] + 1;
    }

    showResults();

}

public static void showResults() {
    System.out.println("You rolled " + numberOfUserRolls + " times the dice.");

    System.out.println("You rolled one " + );
    System.out.println("You rolled two " + );
    System.out.println("You rolled three " + );
    System.out.println("You rolled four " + );
    System.out.println("You rolled five " + );
    System.out.println("You rolled six " + );

    System.out.println("");
    System.out.println("The percentage of 1 is " + + "%" );
    System.out.println("The percentage of 2 is " + + "%" );
    System.out.println("The percentage of 3 is " + + "%" );
    System.out.println("The percentage of 4 is " + + "%" );
    System.out.println("The percentage of 5 is " + + "%" );
    System.out.println("The percentage of 6 is " + + "%" );

    }
}