Apex Class

What is Apex

Apex in Salesforce is a strongly typed object-oriented programming language used to write the code that is executed on the salesforce platform, It is a properietary language developed by salesforce.com, allowing developers to execute flow and transaction control statements on Salesforce servers in conjunction with calls to the API
It enables the developer to add business logic to most of the system events, including button on-clicks, related record updates, VF pages, LWC, and Aura Components.

Features of Apex in Salesforce

Following are the features of the Apex is given below

1) Easy to use

Apex is easy to use as it uses Java like- syntax, which is quite easy to understand and code. It uses simple loop, syntax, block and conditional statement syntax, object and array annotation similar to java

2) Integrated

Apex provide support of DML operations like Insert, Delete, Update and DML exception handling. Furthermore, it supports looping that allows the processing of multiple records at a time. In addition, it has support for SOQL and SOSL query handling, which return a set of subject records.

3) Strongly Typed and Rigorous

It is a strongly typed language, meaning that the user must define the data type of every variable, preventing confusion during compilation.

4) Multitenant Environment

Apex runs in a multitenant environment like other lightning platforms, which means only a single instance runs on the server and serves multiple tenants.

5) Versioned

You can save your code against different versions of the API this enables you to maintain behavior.

6) Easy to Test

Apex provides built-in support to create and run the unit test. It includes the test result so that the user can get to know how much code is covered.

When we should use Apex Code

Customized Application
Tailored Organization Processes
Collaboration with external system
Custom Logic
Complex Validation

Apex Security and Sharing User Mode vs System Mode ?

User Mode

User Mode is when apex code is running by taking the user's permissions and sharing into consideration, Profile permissions, Field Level Permissions, and Sharing rules are respected when code is running in user mode.

System Admin Mode

System Mode is when apex code is running without taking the user's permissions and sharing into consideration. In system mode apex code has access to all objects. fileds and records and user's sharing, FLS, and Profile permissions are not respected.

Enforce Sharing Rules

Apex code runs in system mode by default which means current logged in user's permissions and field level security are not respected during execution. To ensure that sharing rules are not to enforce the sharing rules, are not enforced, class must be declared using without sharing keywordTo enforce the sharing rules, declare the class as With Sharing. inherited sharing keyword is used to run the class in the sharing mode of the class that called it.

With Sharing

With sharing enforces record permissions. it enforces the sharing rules of the current user. Setting a class as with sharing does not enforce object or field-level security permissions!

Without Sharing

Classes declared with this keyword is executed in system mode. Sharing rules for the current user are not enforced when class is declared with this keyword.

Inherited Sharing

To inherit the sharing settings from the parent class (the class that calls it). declare the class with inherited sharing keyword.

Considerations

1. One should always specify a sharing clause.
2. If a class is the entry point into an Apex transaction, not specifying the sharing clause defaults to without sharing.
3. If a class is the entry point into an apex transaction, specifying inherited sharing defaults to with sharing.
4. The sharing setting of the class where a method is defined is applied, not of the class where the method is called from.
5. Classes inherit sharing setting from a parent class when one class extends or implements another.

What are collections in Apex ?

Collection in Apex are data structures that can hold multiple items. Apex supports three types of collection

1) List

An order collection of elements, which allows duplicates and can be accessed by their index.

2) Set :

An unordered collection of unique elements.

3) Map :

a collection of key-value pairs, where each key is unique, and each key maps to a single value.

List Collection

A list can hold any type fo data and is one of the most important type of collection.A list is an ordered collection of any data type such as primitive types, collections, sObjects, user-defined types, and built-in Apex types.
The following are the key features of a list collection in Salesforce.

1. Dublicates an null are allowed in a list colleciton.
2. List is the keyoword to declare a list collection.
3. In a list collection. the index position of the first entry is always zero (0).
4. An Apex list collection has the ability to grow dynamically over time.
5. In a list collection, the data type can be both primitive and non-primitive
6. The keyword followed by the data type has to be used within <> characters to define a list collection

Syntax of List :

List<dataType> listName = new List<datatype>();

List Methods :

1) add(listElement)

Adds an elements t other end of the list.

2) add(index,element)

Insert an element into the list at the specified index position.

3) addAll(fromList)

Adds all of the elements in the specified list to the list that calls the method, Both lists must be of the same type.

4) addAll(formSet)

Add all of the elements in specified set to the list that calls the method. the set and the list must be of the same type.

5) clear()

Remove all elements from a list, consequently setting the list's length to zero.

6) clone()

Makes a duplicate copy of a list.

7) contains(element)

Return true if the list contains the specified element

8) equals(list2)

Compare this list with the specified list and return true if both list are equals, otherwise return false.

9) get(index)

Return the list element stored at the spefified index.

10) isEmpty()

Return true if the list has zero elements.

11) remove(index)

Removes the list elements stored at the specified index, returning the element that was removed.

12) size()

Return the number of elements in the list.

13) sort()

Sorts the items in the list in ascending order.

14) toString() :

Return the string representation of the list.

Set Collection

Set is an unordered collection. it is a unique set of values that do not have any duplicates,if you want no duplicates in your collection. then you should opt for this collection.

Key Features of a set collection in Salesforce :

1. 1. Any data types, such as primitive data types an sObjects, are allowed in a set collection.
  2. A set collection does not have an index.
  3. A set Collection does not contain any duplicates or null values.
  4. Set collections are not widely used in Salesforce Apex.
  5. Sets can hold collections that are nested inside of one another.
  6. You have to used the set keyword followed by the primitive data type name within <> characters to declare a set collection.

The syntax for a set is as follows :

Set<dataType> setName = new Set<dataType>();

Map Collection

Map is a key-value pair that contains each value's unique key. It is used when something neeeds to be located quickly

Key Features of a Map Colelction in Salesforce :

1. Any data type can be used for both the key and the value in a map collection.
2. In a map collection, the null value can be stored in a map key.
3. The keys of type string are case-sensitive in a map collection.
4. The have to use to map keyword followed by the key and value data types enclosed in <> to declare a map collection.

The Syntax of map is as follows :

Map<dataType_key, dataType_value> mapName = new Map<dataType_key, dataType_value>();

Map Methods :

1) put(key,value) :

Associates the specified value with the specified key in the map.

2) putAll(fromMap) :

Copies all of the mappings form the specifed map to the original map.

3) get(key) :

Returns the values to which the specified key is mapped, or null if the map contains no value for this key.

4) keySet() :

Returns a set that contains all of the keys in the map.

5) values() :

Returns a list that contains all the values in the map.

6) equals(map2) :

Compares this map with the specifed map and returns true if both maps are equal, otherwise return false.

7) remove(key) :

Removes the mapping for the specified key from the map, if present and returns the corresponding value.

8) size() :

Returns the number of key-value parise in the map.

9) toString() :

Returns the string representation of the map.

10) isEmpty() :

Returns true if the map has zero key-value pairs