用Java写一个1阶乘到20阶乘的代码

public class Factorial {
public static void main(String[] args) {

for (int i = 1; i <= 20; i++) {
long factorial = 1;
for (int j = 1; j <= i; j++) {
factorial *= j;
}
System.out.println(i + "! = " + factorial);
}

}
}