Why Loops Exist
By the end of this lesson, you'll be able to:
- Explain the problem loops solve compared to writing repeated statements by hand
- Recognize the shape of a repeating task in a business scenario
- Preview the loop types this module covers
Prerequisites: Module 6: "Making Decisions"
The problem: repeating yourself
Imagine debugging the name of 5 accounts one at a time:
System.debug(accountNames[0]);
System.debug(accountNames[1]);
System.debug(accountNames[2]);
System.debug(accountNames[3]);
System.debug(accountNames[4]);This works for 5. It's unworkable for 500, and it breaks the moment the list's size changes. A loop replaces all of this with one block of code that runs once per item, however many items there are.
A real business example: Logistics
List<String> trackingNumbers = new List<String>{'TRK001', 'TRK002', 'TRK003'};
for (String trackingNumber : trackingNumbers) {
System.debug('Checking status for ' + trackingNumber);
}A logistics batch job doesn't know in advance how many shipments it needs to check — it could be 3 or 30,000. A loop handles both identically, which is exactly the point.
What this module covers
Apex gives you several loop shapes for different situations: for, the enhanced for, while, and do-while, plus break/continue for controlling a loop mid-run. The final lesson covers governor limits — the hard ceiling Salesforce places on how much looping code can do, and why it matters more here than almost anywhere else in Apex.
Exercise
In your own words (as a code comment), explain why a loop is better than writing 100 separate System.debug statements.
Show hint
Think about what happens if the number of items changes from 100 to 101.
Why Loops Exist Quiz
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Summary
A loop repeats a block of code without you writing it out by hand — essential once you're working with more than a handful of records, which is nearly always in Salesforce.