int如何在Java数学方程中工作？

Question

I've been reviewing my Java for a class I've taken for the whole year and haven't been doing well on. They have a separate review book called "Be Prepared." I want to see if I get the math behind this line.

result = (1 / 2) * n * (n + 1);    // result is 0.0

The thing is, this is basic basic basic. I need to know if I'm actually getting this. It looks like my like (1/2) is 0.5. That cast to an int is 0. That's why the whole thing is 0.0.

Am I right?

This book is how you get ready for the AP test. Anyone done eimacs who can help?

Answer 1

(1 / 2) will return zero. both are integer and as per integer calculation it will return zero.

Try

result = (1.0 / 2) * n * (n + 1);  

Please have a look at :

• Division of integers in Java

• How do math equations work in Java?

---

In Java the result of each operation is decided by the higher type involved in calculation. It doesn't matter in what type are you assigning the result.

for eg

double d = 10/3;

the value of d will be 3.0 only not 3.33.

Answer 2

Yes, and note that 999 / 1000 will also return 0 . It's truncation, not rounding down.