Conditional (If-Else) Statements

The conditional statement in Apex works similarly to Java.

1if ([Boolean_condition]) 
2    // Statement 1
3else
4    // Statement 2

The else portion is always optional, and always groups with the closest if. For example:

1Integer x, sign;
2// Your code
3if (x <= 0) if (x == 0) sign = 0; else sign = -1;

is equivalent to:

1Integer x, sign;
2// Your code
3if (x <= 0) {
4    if (x == 0) {
5           sign = 0; 
6    } else  {
7           sign = -1;
8    }
9}

Repeated else if statements are also allowed. For example:

1if (place == 1) {
2    medal_color = 'gold';
3} else if (place == 2) {
4    medal_color = 'silver';
5} else if (place == 3) {
6    medal_color = 'bronze';
7} else {
8    medal_color = null;
9}

Apex Developer Guide

Conditional (If-Else) Statements