歌德巴赫猜想_Java

import java.util.*;

public class Welcome {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.println("输入一个大于6的偶数： ");
        int num = in.nextInt();

        if (num > 6 && (num % 2 == 0)) {
            Guess g = new Guess(num);
            g.getValue();
        } else {
            System.out.println("不符合输入规范...");
        }
        in.close();
    }
}

class Guess {
    private int num;

    public Guess () {
        this(8);
    }

    public Guess (int num) {
        this.num = num;
    }

    private boolean isPrime(int i) {
        for (int j = 2; j < i - 1; j++) {
            if (i % j == 0) {
                return false;
            }
        }
        return true;
    }

    public void getValue() {
        for (int i = 4; i <= this.num; i = i + 2) {
            for (int a = 2; a <= i / 2; a++) {
                if (isPrime(a) && isPrime(i - a)) {
                    System.out.println((i + " = " + a + "+" + (i - a)));
                    break;
                }
            }
        }
    }

}