A variable stores a value with a declared type in Apex. Choose types based on the data and operations, and distinguish an unset value from a valid zero or empty string.
Before you begin
Use an authorized development or training organization with fictional records. Record the object names, permissions and configuration used so that someone else can reproduce the exercise.
Work through the idea
First describe the business requirement and the records involved. Keep the exercise separate from a live organization's data and change process. Platform behavior can depend on permissions and configuration; verify those conditions rather than assuming an administrator's result applies to every user.
- Declare appropriate primitive types
- Represent record collections explicitly
- Handle null before accessing a value
Practice task
Design a method that receives an optional amount and returns a validated result.
Check your result
Explain behavior for a positive amount, zero, a negative amount and null.
A mistake to avoid
Do not use a text field for every value just to avoid type decisions.
Keep a review note
Save the inputs or scenario, your reasoning and the result you checked. Explain one assumption and one case that needs more work. Revise the exercise after feedback and distinguish what you demonstrated from what remains untested.
Official reference for further study
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