• Apex Reserved Keywords
• Object Reference for Salesforce and Force.com
• Startung With Apex
• The global access modifier, which is more permissive than the public modifier and allows access across namespaces and applications.
• http://avionsalesforce.blogspot.com/
• https://trendspro.builtwith.com/dashboard
• https://success.salesforce.com/ideaView?id=08730000000DfGeAAK
• https://medium.com/airbnb-engineering/airflow-a-workflow-management-platform-46318b977fd8
• https://salesforce.stackexchange.com/questions/23338/trigger-to-update-parent-object-value-with-child-value

• Sections
  • How Does Apex Work?
  • Apex Core Concepts
  • Execution Context
  • List
  • Maps
  • Trigger and Bulk Request Best Practices
  • Using Maps and Sets in Bulk Triggers
  • Loops
  • Test Driven Development Process
  • Classes, Objects and Interfaces
  • Static and Instance Methods, Variables, and Initialization Code
  • Triggers
  • Apex Test Classes
  • Execution Governor and Limits
  • Data Maninpulation Language
  • Apex Class Metadata Templates
  • Manipulate records with DML
  • Getter Setter
  • Class Methods
  • Batch

When a developer writes and saves Apex code to the platform, the platform application server first compiles the code into an abstract set of instructions that can be understood by the Apex runtime interpreter, and then saves those instructions as metadata.

When an end-user triggers the execution Apex, perhaps by clicking a button or accessing a Visualforce page, the platform application server retrieves the compiled instructions from the metadata and sends them through the runtime interpreter before returning results.

All Apex code runs on the Force.com platform. To guarantee consistent performance and scalability, the execution of Apex is bound by governor limits that ensure no single Apex execution impacts the overall service of Salesforce. This means all Apex code is limited by number of operations (such as DML or SOQL) that it can perfrom within one process. All Apex requests return a collection that contains from 1 to 50,000 records. You cannot assume that your code works only on a single records at a time. Therefore, you must implement programming patterns that take bulk processing into account. Otherwise, you may run into governor limits. public method =

private helper method - it cannot be called externally because it is private.

member variables = attributes

accessor methods = used to access attributes

instance method =

Static method = use static keyword

Static methods are easier to call than instance methods because they dont need to vbe called on an instance of the class but are called directly on the class name.

public scope =

public static method

Methods are defined in a class and objects are instances of a given class.

Constructor is a method that is called at the beginning of an object's lifetime to create and intialize the object.

A class variable is any field declared with the static modifier; this tells the compiler that there is exactly one copy of this variable in existence, regardless of how many times the class has been instantiated.

Instance variables (non-static fields) are unique to each instance of a class. Class variables (static fields) are fields declared with the static modifier; there is exactly one copy of a class variable, regardless of how many times the class has been instantiated. Local variables store temporary state inside a method. Parameters are variables that provide extra information to a method; both local variables and parameters are always classified as "variables" (not "fields").

The term "instance variable" is another name for non-static field.
The term "class variable" is another name for static field.
A local variable stores temporary state; it is declared inside a method.
A variable declared within the opening and closing parenthesis of a method is called a parameter.
What are the eight primitive data types supported by the Java programming language? byte, short, int, long, float, double, boolean, char
Character strings are represented by the class java.lang.String.
An array is a container object that holds a fixed number of values of a single type.

All objects have state and behavior, that is, things that an object knows about itself, and things that an object can do.

An execution context has two characteristics:

• It defines the scope and lifetime of static variables.
• It defines the context for those governor limits that are preset between execution contexts.

There lifetime and scope is defined by the execution context. In other words, static variables can only be accessed from within the execution context in which they are created, and are deleted when the execution context completes.

• Static variables do not persist information between execution contexts. They cannot be used to keep track of the overall execution of the app, or to cache data or objects for use while the app is running.
• Apex does not support the equivalent of application or session variables. Anything you wish to persist must be stored in database objects or custom settings.
• There is no need for synchronization. A given execution context runs on a single thread, so static variables are, in effect, the equivalent of thread local storage - each thread has its own copy of these variables and there is no need to synchronize access.

Use the following syntax when declaring variables:

datatype variable_name [ = value];

In Apex, statements must end in a semicolon and can be one of the following types:

• Assignment, such as assigning a value to a variable.
• Conditional (if-else)
• Loops:
  • Do-while
  • While
  • For
• Locking
• Data Manipulation Language
• Transaction control
• Method invoking
• Exception handling

A block is a series of statements that are grouped together with curly braces and can be used in any place where a single statement would be allowed.

if (true) {
	System.debug(1);
	System.debug(2);
} else {
	System.debug(3);
	System.debug(4);
}

Apex has the following types of collections:

• Lists (Arrays)
• Maps
• Sets

• List Class

A list is a collection of elements, such as Integers, Strings, objects, or other collections. Use a list when the sequence of elements is important. You can have duplicate elements in a list.

The first index position in a list is always [0].

To create a list:

• Use the new keyword
• Use the List keyword followed by the element type contained within <> characters.

To create a list:

List<datatype> list_name
	[= new List<datatype>();] |
	[= new List<datatype>{value, [, value2...]};] |
	;

The following example creates a list of Integer, and assigns it to the variable My_List. Because Apex is strongly typed, you must declare the data type of My_List as a list of Integer.

List<Integer> My_List = new List<Integer>();

A list is an ordered collection of elements that are distinguished by their indices. List elements can be of any data type—primitive types, collections, sObjects, user-defined types, and built-in Apex types.

Lists can contain any collection and can be nested within one another and become multidimensional. For example, you can have a list of lists of sets of Integers. A list can contain up to four levels of nested collections inside it, that is, a total of five levels overall.

To declare a list, use the List keyword followed by the primitive data, sObject, nested list, map, or set type within <> characters.

For example:

// Create an empty list of String
List<String> my_list = new List<String>();
// Create a nested list
List<List<Set<Integer>>> my_list_2 = new List<List<Set<Integer>>>();

To access elements in a list, use the List methods provided by Apex. For example:

List<Integer> myList = new List<Integer>(); // Define a new list
myList.add(47);                    // Adds a second element of value 47 to the end 
                                       // of the list
Integer i = myList.get(0);                   // Retrieves the element at index 0
myList.set(0, 1);                           // Adds the integer 1 to the list at index 0
myList.clear();                    // Removes all elements from the list

A set is a collection of unique unordered elements.

To create a set:

• Use the new keyword
• Use the Set keyword followed by the primitive data type contained within <> characters.

Syntax for creating a Set:

Set<datatype> set_name
	[= new Set<datatype>();] |
	[= new Set<datatype>{value [, value2...]};] |
;

The following example creates a set of String. The values for the set are passed in curly braces.

Set<String> My_String = new Set<String>{'a', 'b', 'c'};

• Maps

A map is a collection of key-value pairs where each unique key maps to a single value. Keys and values can be any data type—primitive types, collections, sObjects, user-defined types, and built-in Apex types.

Map keys and values can contain any collection, and can contain nested collections. Map keys can contain up to only four levels of nested collections.

• Map keys can contain up to four levels of nested collections.
• To declare a map, use the Map keyword by the data types of the key and the within <> characters.
• Apex uses hash structure for all maps.
• The iteration order of map elements is deterministic. You can rely on the order being the same in each subsequent execution of the same code. However, we recommend to always access map elements by key.
• A map key can hold the null value.
• Adding a map entry with a key that matches an existing key in the map overwrites the existing entry with that key with the new entry.
• Map keys of type String are case-sensitive. Two keys that differ only by the case are considered unique and have corresponding distinct Map entries. Subsequently, the Map methods, including put, get, containsKey, and remove treat these keys as distinct.
• A Map object is serializable into JSON only if it uses one of the following data types as a key.
  • Boolean
  • Date
  • DateTime
  • Decimal
  • Double
  • Enum
  • Id
  • Integer
  • Long
  • String
  • Time

To declare a map, use the Map keyword followed by the data types of the key and the value within <> characters. For example:

Map<String, String> country_currencies = new Map<String, String>();
Map<ID, Set<String>> m = new Map<ID, Set<String>>();

As with lists, you can populate map key-value pairs when the map is declared by using curly brace ({}) syntax. Within the curly braces, specify the key first, then specify the value for that key using =>. For example:

Map<String, String> MyStrings = new Map<String, String>{'a' => 'b', 'c' => 'd'.toUpperCase()};

To access elements in a map, use the Map methods provided by Apex. This example creates a map of integer keys and string values. It adds two entries, checks for the existence of the first key, retrieves the value for the second entry, and finally gets the set of all keys.

Map<Integer, String> m = new Map<Integer, String>(); // Define a new map
m.put(1, 'First entry');                  // Insert a new key-value pair in the map
m.put(2, 'Second entry');                  // Insert a new key-value pair in the map
System.assert(m.containsKey(1));  // Assert that the map contains a key
String value = m.get(2);               // Retrieve a value, given a particular key
System.assertEquals('Second entry', value);
Set<Integer> s = m.keySet();       // Return a set that contains all of the keys in the map

Set and map data structures are critical for successful coding of bulk triggers. Sets can be used to isolate distinct records, while maps can be used to hold query results organized by record ID.

For example, this bulk trigger from the sample quoting application first adds each pricebook entry associated with the OpportunityLineItem records in Trigger.new to a set, ensuring that the set contains only distinct elements. It then queries the PricebookEntries for their associated product color, and places the results in a map. Once the map is created, the trigger iterates through the OpportunityLineItems in Trigger.new and uses the map to assign the appropriate color.

// When a new line item is added to an opportunity, this trigger copies the value of the
// associated product's color to the new record.
trigger oppLineTrigger on OpportunityLineItem (before insert) {

    // For every OpportunityLineItem record, add its associated pricebook entry
    // to a set so there are no duplicates.
    Set<Id> pbeIds = new Set<Id>();
    for (OpportunityLineItem oli : Trigger.new) 
        pbeIds.add(oli.pricebookentryid);

    // Query the PricebookEntries for their associated product color and place the results
    // in a map.
    Map<Id, PricebookEntry> entries = new Map<Id, PricebookEntry>(
        [select product2.color__c from pricebookentry 
         where id in :pbeIds]);
         
    // Now use the map to set the appropriate color on every OpportunityLineItem processed
    // by the trigger.
    for (OpportunityLineItem oli : Trigger.new) 
        oli.color__c = entries.get(oli.pricebookEntryId).product2.color__c;  
}

The following example creates a map that has a data type of Integer for the key and String for the value. In this example, the values for the map are being passed in between the curly braces as the map is being created.

Map<Integer, String> My_Map = new Map<Integer, String>{1 => 'a', 2=> 'b', 3 => 'c'};

Apex triggers are optimized to operate in bulk, which, by definition, requires developers to write logic that supports bulk operations.

This example demonstrates the correct pattern to support the bulk nature of triggers while respecting the governor limits:

Trigger MileageTrigger on Mileage__c (before insert, before update) {
	Set<ID> ids = Trigger.newMap.keySet();
	List<User> c = [SELECT Id FROM user WHERE mileage__c in :ids];
}

This pattern respects the bulk nature of the trigger by passing the Trigger.new collection to a set, then using the set in a single SOQL query. This pattern captures all incoming records within the request while limiting the number of SOQL queries.

Best practices for designing bulk patterns:

• Minimize the number of DML operations by adding records to collections and performing DML operations against these collections.
• Minimize the number of SOQL statements by preprocessing records and generating sets, which can be places in single SOQL statement used with the IN clause.

Use the Trigger.newMap and Trigger.oldMap ID-to-sObject maps to correlate records with query results. For example, this trigger from the sample quoting app uses Trigger.oldMap to create a set of unique IDs (Trigger.oldMap.keySet()). The set is then used as part of a query to create a list of quotes associated with the opportunities being processed by the trigger. For every quote returned by the query, the related opportunity is retrieved from Trigger.oldMap and prevented from being deleted:

trigger oppTrigger on Opportunity (before delete) {
    for (Quote__c q : [SELECT opportunity__c FROM quote__c 
                       WHERE opportunity__c IN :Trigger.oldMap.keySet()]) {
        Trigger.oldMap.get(q.opportunity__c).addError('Cannot delete 
                                                       opportunity with a quote');
    }
}

Use the following design pattern in the trigger to determine if this was the first or subsequent call for this execution context:

if (!myclass.firstcall)
{
	// First call into trigger
	myclass.firstcall = true;
}
else
{
	// Subsequent call into trigger
}

A class static variable is a global variable that is associated with a particular class. It exists regardless of whether you have actually created an instance of the class, and that a single instance of the variable is shared by all instances of the class and, in fact, by the entire application.

While the if statement enables your application to do things based on a condition, loops tell your application to do the same thing again and again based on a condition. Apex supports the following types of loops:

• Do-While
• While
• For

A Do-While loop checks the condition after the code has executed. A While loop checks the condition at the start, before the code executes. A For loop enables you to more finely control the condition used with the loop. Apex supports traditional For loops where you set the conditions, as well as For loops that use lists and SOQL queries as part of the condition.

Test driven development process is test development that occurs at the same time as development of code.

Apex supports the creation and execution of unit tests. Unit tests are class methods that verify whether a particular piece of code is working properly. Unit test methods take no arguments, commit no data to the database, send no emails, are flagged with the testMethod keyword or the isTest annotation in the method definition. Test methods must be defined in test classes, that is, classes annotated with isTest.

• At least 75% of Apex code must be covered by unit tests and all of those tests must complete successfully.
• When deploying Apex to a production org, each unit test in org namespace is executed bu default
• Calls to System.debug are not counted as part of Apex code coverage.
• Test methods and test classes are not counted as part of Apex code coverage.
• Every trigger must have some code coverage.
• All classes and triggers must compile successfully.

https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_classes.htm

https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_classes_static.htm

With Static Methods you do not need to create an instance of the class to access the method - you can just use the name of the class followed by a dot(.) notation and the name of the method.

b.Price__c *= 0.9;

This statement takes the old value of b.Price__c multiples it by 0.9 and then stores the new value into the b.Price__c field.

public class MyHelloWorld {
	public static void applyDiscount (Book__c[] books) {
		for (Book__c b :books) {
			b.Price__c *= 0.9;
		}
	}
}

Static methods are easier to call than instance methods because they don’t need to be called on an instance of the class but are called directly on the class name.

trigger HelloWorldTrigger on Book__c (before insert) {
	
	Book__c[] books = Trigger.new;
	
	MyHelloWorld.applyDiscount (books);
}

Book__c[] books = Trigger.new; creates a list of book records named books and assigns it the contents of a trigger context variable called Trigger.new. Trigger context variables are implicitly defined in all triggers and provide access to the records that caused the trigger to fire. In this case, Trigger.new contains all the new books that are about to be inserted.

MyHelloWorld.applyDiscount (books); the code calls the method applyDiscount in the MyHelloWorld class. It passes in the array of new books.

@isTest
private class HelloWorldTestClass {
	static testMethod void validateHelloWorld() {
		Book__c b = new Book__c (Name='Behind the cloud', Price__c = 100);
		System.debug('Price before inserting new book: ' + b.Price__c);
		
		// Insert book
		insert b;
		
		// Retrieve the new book
		b = [SELECT Price__c FROM Book__c WHERE Id = :b.Id];
		System.debug('Price after triggger fired: ' + b.Price__c);
		
		// Test that the trigger correctly updated the price
		System.assertEquals(90, b.Price__c);
	}
}

https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_gov_limits.htm#total_heap_size_limit_desc

DML provides a straightforward way to manage records by providing simple statements to insert, update, merge, delete, and restore records.

The upsert DML operation creates new records and updates sObject records within a single statement, using a specified field to determine the presence of existing objects, or the ID field if no field is specified.

The merge statement merges up to three records of the same sObject type into one of the records, deleting the others, and re-parenting any related records.

If a DML operation fails, it returns an exception of type DmlException. You can catch exceptions in your code to handle error conditions.

This example adds the Acme account to Salesforce. An account sObject is created first and then passed as an argument to the insert statement, which persists the record in Salesforce.

// Create the account sObject
Account acct = new Account (Name='Acme', Phone='(415)-635-9877', NumberOfEmployees=100);
// Insert the account by using DML
insert acct;

This example shows how to get the ID on the sObject that corresponds to the inserted account.

// Create the account sObject 
Account acct = new Account(Name='Acme', Phone='(415)555-1212', NumberOfEmployees=100);
// Insert the account by using DML
insert acct;

// Get the new ID on the inserted sObject argument
ID acctID = acct.Id;
// Display this ID in the debug log
System.debug('ID = ' + acctID);

// Debug log result (the ID will be different in your case)
// DEBUG|ID = 001D000000JmKkeIAF

Performing bulk DML operations is the recommended way because it helps avoid hitting governor limits, such as the DML limit of 150 statements per Apex transaction.

This example inserts contacts in bulk by inserting a list of contacts in one call. The sample then updates those contacts in bulk too.

// Create a list of contacts
List<Contact> conList = new List<Contact> {
    new Contact(FirstName='Joe',LastName='Smith',Department='Finance'),
        new Contact(FirstName='Kathy',LastName='Smith',Department='Technology'),
        new Contact(FirstName='Caroline',LastName='Roth',Department='Finance'),
        new Contact(FirstName='Kim',LastName='Shain',Department='Education')};
            
// Bulk insert all contacts with one DML call
insert conList;

// List to hold the new contacts to update
List<Contact> listToUpdate = new List<Contact>();

// Iterate through the list and add a title only
//   if the department is Finance
for(Contact con : conList) {
    if (con.Department == 'Finance') {
        con.Title = 'Financial analyst';
        // Add updated contact sObject to the list.
        listToUpdate.add(con);
    }
}

// Bulk update all contacts with one DML call
update listToUpdate;

Persistence refers to the characteristic of state that outlives the process that created it. This is achieved in practice by storing the state as data in computer data storage. Programs have to transfer data to and from storage devices and have to provide mappings from the native programming-language data structures to the storage device data structures.

public interface {{ api_name }} {

	//Define the method signature to be implemented in classes that implements the interface
	//Example method
	Integer operation();
}

public class {{ api_name }} implements Auth.RegistrationHandler {
    
    public User createUser(Id portalId, Auth.UserData data) {
        
		// Match the Auth.UserData to an existing user?
		// Update user details from Auth.UserData?
		// Provision a new user where the User does not exist?
		
        return null;
    }
    
    public void updateUser(Id userId, Id portalId, Auth.UserData data) {
        
		// Update user details from Auth.UserData?
		
    }
}

• process records asynchronously in batches to stay within platform limits.

• The execution logic of the batch class is called once for each batch of records you are processing.

• Each time you invoke a batch class, the job is placed on the Apex job queue and is executed as a discrete transaction.

  • Advantages:
  • Every transaction starts with a new set of governor limits, making it easier to ensure that your code stays within the governor execution limits.
  • If one batch fails to process successfully, all other successful batch transactions aren’t rolled back.

• class must implement the Database.Batchable interface and include the following three methods:

  • start - Used to collect the records or objects to be passed to the interface method execute for processing. This method is called once at the beginning of a Batch Apex job and returns either a Database.QueryLocator object or an Iterable that contains the records or objects passed to the job.

• To ensure fast execution of batch jobs, minimize Web service callout times and tune queries used in your batch Apex code.

global class {{ api_name }} implements Database.Batchable<sObject> {
	
	String query;
	
	global {{ api_name }}() {
		
	}
	
	global Database.QueryLocator start(Database.BatchableContext BC) {
		return Database.getQueryLocator(query);
	}

   	global void execute(Database.BatchableContext BC, List<sObject> scope) {
	
	}
	
	global void finish(Database.BatchableContext BC) {
		
	}
	
}

@isTest
private class {{ api_name }}
{
	@isTest
	static void itShould()
	{
		// Given


		// When


		// Then

	}
}

public with sharing class {{ api_name }} {

	private final sObject mysObject;

    // The extension constructor initializes the private member
    // variable mysObject by using the getRecord method from the standard
    // controller.
    public {{ api_name }}(ApexPages.StandardController stdController) {
        this.mysObject = (sObject)stdController.getRecord();
    }

    public String getRecordName() {
        return 'Hello ' + (String)mysObject.get('name') + ' (' + (Id)mysObject.get('Id') + ')';
    }
}

public class {{ api_name }} extends Exception {

}

public with sharing class {{ api_name }} implements Iterable<{{ type_name }}> {

  public Iterator<{{ type_name }}> Iterator(){
    return new {{ iterator_class_name }}();
  }
  
}

public class {{ api_name }} implements Iterator<{{ type_name }}> {

  {{ type_name }}[] results { get;set; }
  Integer index { get;set; }
  String query;

  public {{ api_name }}() {
    index = 0;
    results = Database.query(query);   
  }

  public Boolean hasNext(){ 
   return results != null && !results.isEmpty() && index < results.size(); 
  }    

  public {{ type_name }} next() { 
    return results[index++];
  }    

}

/**
 * See https://github.com/financialforcedev/fflib-apex-common for more info
 *
 * Install library via 
 *   https://githubsfdeploy.herokuapp.com/app/githubdeploy/financialforcedev/fflib-apex-common
 */

/**
 * Encapsulates all behaviour logic relating to the {{ object_name }} object
 * 
 * For more guidelines and details see 
 *   https://developer.salesforce.com/page/Apex_Enterprise_Patterns_-_Domain_Layer
 *
 **/
public class {{ api_name }} extends fflib_SObjectDomain 
{
	public {{ api_name }}(List<{{ object_name }}> records) 
	{
		super(records);	
	}

	public override void onValidate()
	{
		for({{ object_name }} record : (List<{{ object_name }}>) Records)
		{
		}
	}

	public override void onValidate(Map<Id,SObject> existingRecords)
	{
		for({{ object_name }} record : (List<{{ object_name }}>) Records)
		{
		}
	}

	public override void onBeforeInsert()
	{
		for({{ object_name }} record : (List<{{ object_name }}>) Records)
		{
		}
	}

	public void someMethod()
	{
		for({{ object_name }} record : (List<{{ object_name }}>) Records)
		{
		}		
	}

	public class Constructor implements fflib_SObjectDomain.IConstructable2
	{
		public fflib_SObjectDomain construct(List<SObject> sObjectList)
		{
			return new {{ api_name }}(sObjectList);
		}

		public fflib_SObjectDomain construct(List<SObject> sObjectList, SObjectType sObjectType)
		{
			return new {{ api_name }}(sObjectList);
		}			
	}	
}

• The upsert DML operation creates new records and updates sObject records within a single statement, using a specified field to determine the presence of existing objects, or the ID field if no field is specified.
• The merge statement merges up to three records of the same sObject type into one of the records, deleting the others, and re-parenting any related records.
• When inserting records, the system assigns an ID for each record. In addition to persisting the ID value in the database, the ID value is also autopopulated on the sObject variable that you used as an argument in the DML call.
• This example shows how to get the ID on the sObject that corresponds to the inserted account.

// Create the account sObject 
Account acct = new Account(Name='Acme', Phone='(415)555-1212', NumberOfEmployees=100);
// Insert the account by using DML
insert acct;

// Get the new ID on the inserted sObject argument
ID acctID = acct.Id;
// Display this ID in the debug log
System.debug('ID = ' + acctID);

// Debug log result (the ID will be different in your case)
// DEBUG|ID = 001D000000JmKkeIAF

• DML limit of 150 statements per Apex transaction.
• This example inserts contacts in bulk by inserting a list of contacts in one call. The sample then updates those contacts in bulk too.

// Create a list of contacts
List<Contact> conList = new List<Contact> {
    new Contact(FirstName='Joe',LastName='Smith',Department='Finance'),
        new Contact(FirstName='Kathy',LastName='Smith',Department='Technology'),
        new Contact(FirstName='Caroline',LastName='Roth',Department='Finance'),
        new Contact(FirstName='Kim',LastName='Shain',Department='Education')};
            
// Bulk insert all contacts with one DML call
insert conList;

// List to hold the new contacts to update
List<Contact> listToUpdate = new List<Contact>();

// Iterate through the list and add a title only
//   if the department is Finance
for(Contact con : conList) {
    if (con.Department == 'Finance') {
        con.Title = 'Financial analyst';
        // Add updated contact sObject to the list.
        listToUpdate.add(con);
    }
}

// Bulk update all contacts with one DML call
update listToUpdate;

• You can insert records related to existing records if a relationship has already been defined between the two objects, such as a lookup or master-detail relationship.
• A record is associated with a related record through a foreign key ID.
• For example, if inserting a new contact, you can specify the contact's related account record by setting the value of the AccountId field.
• This example shows how to add a contact to an account (the related record) by setting the AccountId field on the contact. Contact and Account are linked through a lookup relationship.

Account acct = new Account(Name='SFDC Account');
insert acct;

// Once the account is inserted, the sObject will be 
// populated with an ID.
// Get this ID.
ID acctID = acct.ID;

// Add a contact to this account.
Contact mario = new Contact(
    FirstName='Mario',
    LastName='Ruiz',
    Phone='415.555.1212',
    AccountId=acctID);
insert mario;

• Fields on related records can't be updated with the same call to the DML operation and require a separate DML call.
• For example, if inserting a new contact, you can specify the contact's related account record by setting the value of the AccountId field. However, you can't change the account's name without updating the account itself with a separate DML call.
• The following example updates a contact and its related account using two update statements.

// Query for the contact, which has been associated with an account.
Contact queriedContact = [SELECT Account.Name 
                          FROM Contact 
                          WHERE FirstName = 'Mario' AND LastName='Ruiz'
                          LIMIT 1];

// Update the contact's phone number
queriedContact.Phone = '(415)555-1213';

// Update the related account industry
queriedContact.Account.Industry = 'Technology';

// Make two separate calls 
// 1. This call is to update the contact's phone.
update queriedContact;
// 2. This call is to update the related account's Industry field.
update queriedContact.Account; 

public class MyClass {
	public String myVariable {get; set;}
}

public class MyClass {
	public String myVariable;
	
	public void setMyVariable(String input){
		myVariable = input;
	}
	
	public String getMyVariable(){
		return myVariable;
	}
}

• void - if the method does not return a value.