Introduction to Apex

Question 1

What is Apex?

Answer 1

Apex is Salesforce’s case-insensitive, cloud-hosted, Java-like, multitenant-aware, object-oriented, proprietary, strongly-typed, versioned programming language

Question 2

What is a class?

Answer 2

a class is a template for objects that contains the methods (i.e. functions) that will define an object’s behavior and the variables that will hold an object’s state

Question 3

What is an object?

Answer 3

an object is an instance of a class that has state (things that it knows about itself) and behavior (things that it can do)

Question 4

What are the two types of type casting?

Answer 4

Explicit Type Casting

Implicit Type Casting

Question 5

What is Explicit Type Casting?

Answer 5

Explicit Type Casting

• we convert between unrelated data types by invoking conversion methods
• many of the classes representing Apex variables have methods to convert values between data types
• we can also convert between related data types by putting the desired data type in parentheses after the assignment operator

String a = ‘1’;

Integer b = Integer.valueOf(a);

Question 6

What is Implicit Type Casting?

Answer 6

Implicit Type Casting

• done automatically by language
• two types

casting between numeric primitive data types (hierarchy)

Integer can convert to => Long… => Double… => Decimal

casting between Ids and Strings

Integer a = 1;

Decimal b = a;

Question 7

What are Lists?

Answer 7

• comma-separated, ordered, indexed groups of values (i.e. elements) that all share the same data type
• because Lists are ordered and indexed, we can access individual elements through their index in the List and the List can contain duplicate values
• Lists are zero-indexed,

Question 8

Can you create a new list shoppingList and populate it with a “Cereal” and “Milk”?

Answer 8

List shoppingList = new List();
‘Cereal’,
‘Milk’
};

OR

List shoppingList = new List();
shoppingList.add(‘Cereal’);
shoppingList.add(‘Milk’);

Question 9

What are sets? What methods does it have?

Answer 9

unordered collections and therefore must contain unique values

• add() - add element to set
• size() - returns size of set
• contains() - returns true/false

Question 10

What is a Map?

Answer 10

groups of key-value pairs where each key must be unique, but we can have duplicate values

Question 11

What do the following Control Flow do?

• Conditional Statements
• Switch Statements
• While and Do Loops
• For Loop

Answer 11

Conditional Statements

if ([Boolean_condition])

// Statement 1

else

// Statement 2

Switch Statements

switch on expression {

when value1 {

// code block 1

} when value2 {

code block 2

} when else { // default block, optional

// code block 4

}

}

While and Do Loops

while (condition) {

code_block

}

do {

code_block

} while (condition);

For Loop

Traditional

for (init; exit_condition; iterator) {

code_block

}

For Loop to iterate through Lists and Sets

for (variable : list_or_set) {

code_block

}