Apex Coding Basics

Hope this page will help you to understand coding basic of the apex. Here in this post, I will explain class, datatypes, variables, and constants.

What is Apex class?

A class is the group of variables and methods. We can create a class in Salesforce in different ways. See the below post to know about apex class.

Apex Class – Simple Class to understand Apex

Data types & Variables – Coding basics

Data types are used to define variables and methods in classes. In Apex, all variables & expressions have one of the below data types. Those are 

  • Primitive data types (Integer, Boolean, String, …… etc.)
  • Enum (an enumerated list)
  • sObjects (sObject, or Account, contact, object__c….)
  • Collection (list, set, map)
  • Null (for the null constant. Which can be assigned to any variable.
  • An object created by the user – or system-defined classes.

1. Primitive data types: know more about primitive data types

2. Enumerated list or Enum data type: Enumerated list (or Enum) is an abstract data type that stores one value of a finite set of specified identifiers. To define Enum, use the enum keyword in the variable declaration and then define the list of values. You can use enums to specify a set of constants. Know more about Enum

3. sObjects: Know more about sObject types

4. Collection data types: Three types of collection are available in Apex

List: An ordered collection of primitives, sObjects, collections, or Apex objects based on indices.
Set: An unordered collection of unique primitives.
Map: A collection of unique, primitive keys that map to single values which can be primitives, sObjects, collections, or Apex objects.

– Collections can have not more than 1000 elements.
– Lists and maps may contain other collections – Collections can only be nested up to five levels deep.
– Collections do not support adding or removing elements while iterating over the collections. Know more about collections

Variables – coding basics

Static keyword is used to define static variables to store data that is shared within the class.

– Static variables are not memory constants.
– All instances of the same class share a single copy of the static variable.
– This can be a technique used for setting flags to prevent recursive triggers.

What is final keyword? 

    Final keyword is used to define constants – this indicates that the variable can only be assigned once, either in the declaration itself or with a static initializer method if the constant is defined in the class.

private final Integer j=10;