Conditional (If-Else) Statements

The conditional statement in Apex works similarly to Java.
if ([Boolean_condition]) 
    // Statement 1
else
    // Statement 2
The else portion is always optional, and always groups with the closest if. For example:
Integer x, sign;
// Your code
if (x <= 0) if (x == 0) sign = 0; else sign = -1;
is equivalent to:
Integer x, sign;
// Your code
if (x <= 0) {
    if (x == 0) {
           sign = 0; 
    } else  {
           sign = -1;
    }
}
Repeated else if statements are also allowed. For example:
if (place == 1) {
    medal_color = 'gold';
} else if (place == 2) {
    medal_color = 'silver';
} else if (place == 3) {
    medal_color = 'bronze';
} else {
    medal_color = null;
}