When does the binary operators execution happen in Java?

Question

I\'m trying to understand java byte code. I started with simple example:

public class Test
{
    public static void main(String args[])
    {
        System.         


        

Answer 1

2 + 1 is a compile-time constant expression. The compiler itself replaces it by 3 in the byte-code.

See the Java Language Specification, which says:

Some expressions have a value that can be determined at compile time. These are constant expressions.

See this other chapter for what constitutes a constant expression

A constant expression is an expression denoting a value of primitive type or a String that does not complete abruptly and is composed using only the following:

• Literals of primitive type and literals of type String [...]
• The additive operators + and - [...]