Operator precedence in Java

Question

In one example from http://leepoint.net/notes-java/data/expressions/precedence.html

The following expression

1 + 2 - 3 * 4 / 5

Is

Answer 1

I am slightly confused as to how it is decided which will be evaluated first when * and / are involved

That's why we have specifications :)

Section 15.7 is the section of the Java Language Specification which deals with evaluation order, and section 15.17 states:

The operators *, /, and % are called the multiplicative operators. They have the same precedence and are syntactically left-associative (they group left-to-right).

So whenever there is A op1 B op2 C and both op1 and op2 are *, / or % it's equivalent to

(A op1 B) op2 C

Or to put it another way - the second linked article is plain wrong in their example. Here's an example to prove it:

int x = Integer.MAX_VALUE / 2;        
System.out.println(x * 3 / 3);
System.out.println((x * 3) / 3);
System.out.println(x * (3 / 3));

Output:

-357913942
-357913942
1073741823

That shows the multiplication happening first (leading to integer overflow) rather than the division (which would end up with a multiplication of 1).