Statistical Distributions

import java.util.Scanner;
class Distributions{
    static Scanner sc = new Scanner(System.in);
    static long fact(int n){
        long ans = 1;
        for(int i = 2; i <= n; i++)
            ans*=i;
        return ans;
    }
    static long comb(int n, int x){
        return fact(n)/(fact(x)*fact(n-x));
    }
    static double bernoulli(double p, int n, int x){
        return (comb(n, x)*Math.pow(p, x)*Math.pow(1-p, n-x));
    }
    static double poisson(int lamda, int x){
        return Math.exp(-lamda)*Math.pow(lamda, x)/fact(x);
    }
    static double uniform(int a, int b, int x){
        if(x>=a && x<=b)
            return Math.pow(a-b, -1);
        else return 0;
    }
    static double normal(double sigma, double mew, int x){
        return Math.pow(sigma*Math.sqrt(2*Math.PI), -1)*Math.exp(-(Math.pow(x-mew, 2))/(2*Math.pow(sigma, 2)));
    }
    static int takeInt(String prompt){
        System.out.print(prompt+": ");
        return sc.nextInt();
    }
    static double takeDouble(String prompt){
        System.out.print(prompt+": ");
        return sc.nextDouble();
    }
    public static void main(String[] args){
        int lambda, n, a, b; double p, sigma, mew;
        while(true){
            switch(takeInt("1.Discrete 2.Continous 3.exit")){
                case 1:
                    switch(takeInt("1.Binomial 2.Poisson")){
                        case 1:
                            do{p = takeDouble("p");}while(p>1||p<0);
                            do{n = takeInt("n");}while(n<1);
                            for(int i = 0; i <= n; i++)
                                System.out.println("p("+i+") = "+bernoulli(p, n, i));
                            break;
                        case 2:
                            do{lambda = takeInt("lambda");}while(lambda<0);
                            do{n = takeInt("n");}while(n<1);
                            for(int i = 0; i <= n; i++)
                                System.out.println("p("+i+") = "+poisson(lambda, i));
                            break;
                        default:
                            System.out.println("Enter 1 or 2.");
                    }
                    break;
                case 2:
                    switch(takeInt("1.Normal 2.Uniform")){
                        case 1:
                            do{sigma = takeDouble("sigma");}while(sigma<0);
                            do{mew = takeDouble("mew");}while(mew<0);
                            do{n = takeInt("n");}while(n<1);
                            for(int i = 0; i <=n ; i++)
                                System.out.println("p("+i+") = "+normal(sigma, mew, i));
                            break;
                        case 2:
                            do{a = takeInt("a");}while(a<0);
                            do{b = takeInt("b");}while(b<=a);
                            for(int i = 0; i < b+6; i++)
                                System.out.println("p("+i+") = "+uniform(a, b, i));
                            break;
                        default:
                            System.out.println("Enter 1 or 2.");
                    }
                    break;
                case 3: return;
                default:
                    System.out.println("Enter a number from 1 to 3.");
            }
        }
    }
}