If Statements

Integer stockLevel = 3;

if (stockLevel < 5) {
    System.debug('Low stock warning!');
}

1. Integer stockLevel = 3; — the current stock count.
2. (blank line)
3. if (stockLevel < 5) { — the condition inside ( ) must evaluate to a Boolean. Here it's true, so the block below runs.
4. System.debug('Low stock warning!'); — runs because line 3 was true.
5. } — closes the if block. If line 3 had been false, this whole block would simply be skipped and execution would continue after line 5.

Integer rawMaterialUnits = 120;
Integer reorderThreshold = 100;

if (rawMaterialUnits < reorderThreshold) {
    System.debug('Trigger a purchase order for raw materials.');
}

1. Integer rawMaterialUnits = 120; — units currently on hand.
2. Integer reorderThreshold = 100; — the reorder point.
3. (blank line)
4. if (rawMaterialUnits < reorderThreshold) { — false here (120 is not less than 100), so the block below is skipped.
5. System.debug('Trigger a purchase order for raw materials.'); — does not run in this case.
6. } — closes the if block.

This is a real, common manufacturing rule expressed directly as an if statement — no framework, no magic, just a condition and a reaction.

• Skipping the curly braces for a single-line if. Apex allows if (x) doSomething(); without braces, but it's fragile — the next line someone adds might silently fall outside the if without them noticing. Always use { }, even for one line.
• Putting an assignment (=) instead of a comparison (==) in the condition. if (x = 5) is a compile error in Apex for primitive Booleans — a helpful safety net compared to some other languages.

1. Integer temperature = 22; — the reading.
2. (blank line)
3. if (temperature > 30) { — false, since 22 is not greater than 30.
4. System.debug('Too hot!'); — skipped — this never runs.
5. } — closes the if block.
6. (blank line)
7. System.debug('Done checking temperature.'); — runs regardless of what happened above; it isn't inside the if block, so it always executes.