为什么 Java 不能正确计算这个计算？

Question

I have recently started learning Java. I started working on a simple mathematical project for approximating Euler number with (1 + 1 / x)^x. But at the very first step, the program returned the wrong value. Here is my minimised code, where the solution is wrong.

public class MyClass
{
    public static void main(String[] args)
    {
        System.out.println(1 + 1 / 2);
    }
}

The program returns 1. The result seems to me pretty contradictory. How can 1 + 1 / 2 return 1? I was expecting 1.5.

I tried some debugging:

double x = 1 + Math.pow(2, -1);
System.out.println(x);

And now it is working. How come that?

Answer 1

I was making a division on the two integers. I should make this on two doubles or floats:

System.out.println(1.0 + 1.0 / 2.0);

And since we can shorten the doubles 1.0 -> 1., we could shorten this:

System.out.println(1.+1./2.);

Thank you for your answer! (Especially Naman , njzk2 and FredK in the comments.)