一个偶数总能表示为两个素数之和

package cskaoyan;
 
public class cskaoyan44 {
    @org.junit.Test
    public void sum() {
        java.util.Scanner in = new java.util.Scanner(System.in);
        long number = 0;
 
        do {
            System.out.println("请输入一个偶数:");
            number = in.nextLong();
        } while (number % 2 != 0);
 
        for (long i = 2; i < number; i++) {
            if (isPrime(i) && isPrime(number - i)) {
                System.out.println("偶数" + number + "可以分解成" + i + "和" + (number - i) + "两个素数的和");
                break;
            }
        }
 
        in.close();
    }
 
    private static boolean isPrime(long number) {
        boolean flag = true;
 
        if (number < 2) {
            flag = false;
        } else if (number < 4) {
            flag = true;
        } else if (number % 2 == 0) {
            flag = false;
        } else {
            for (long i = 3; i < Math.sqrt(number) + 1; i++) {
                if (number % i == 0) {
                    flag = false;
                    break;
                }
            }
        }
 
        return flag;
    }
}