Keywords used in Primitive-Collection Types

Primitive Type Keyword

Below are the primitive data type keywords used in apex langue to declare variables.

1. Blob

This data type represents binary data stored as a single object.

Example

Blob b1 = Blob.valueof('idea');

2. Boolean

This data type represents Value that can only be assigned true, false, or null.
Example:

Boolean isvar = true;

3. Date

This data type represents particular day.
Example:

Date myDateVar = Date.today();
Date weekStart = myDateVar.toStartofWeek();

4. Datetime

This data type represents particular time and date.

Example:

Datetime myDateTimeVar = Datetime.now();
Datetime newd = myDateTimeVar. addMonths(5);

5. Decimal

This data type represents Number that includes a decimal
point. Decimal is an arbitrary precision number.

Example:

Decimal myVar = 12.4567;
Decimal divDecVar = myVar.divide(7, 2, System.RoundingMode.UP);
system.assertEquals(divDecVar,1.78);

6. Double

Represents 64-bit number that includes a decimal point. Minimum value -2^63. Maximum value of 2^63-1.

Example:

Double d=3.14159;

7. ID

Represents 18-character Force.com record identifier.
Example:

ID id='00300000003T2PGAA0';

8. Integer

32-bit number that doesn’t include a decimal point. Minimum value
-2,147,483,648 — maximum value of 2,147,483,647

Example:

Integer i = 1;

9. Long

Represents 64-bit number that doesn’t include a decimal point. minimum value of -263 — maximum value of 263-1.

Example:

Long l = 2147483648L;

10. String

Represents Set of characters surrounded by single quotes.

Example:

String s1 = 'Hello';

11. Time

Represents particular time.
Example:

Time myTimeVar = Time.newInstance(18, 30, 2, 20);
Integer myMinutes = myTimeVar.
minute();

List Type Keywords

Below are the Collection Type keyword used in Apex:

1. List

Ordered collection of typed primitives, sObjects, objects, or collections that are distinguished by their indices.

Example:

// Create an empty list of String
List<String> my_list = new List<String>();
My_list.add('first');
String x = my_list.get(0);
// Create list of records from a query
List<Account> accs = [SELECT Id, Name FROM Account LIMIT 1000];

2. Map

Collection of key-value pairs where each unique key maps to a single value. Keys can be any primitive data type, while values can be a primitive, sObject,
collection type, or an object.

Example:

Map<String, String> mys = new Map<String,String>();
Map<String, String> mys = new Map<String,
String>{'a' => 'b', 'c' => 'd'.toUpperCase()};
Account myAcct = new Account();
Map<Integer, Account> m = new
Map<Integer, Account>();
m.put(1, myAcct);

3. Set

Unordered collection that doesn’t contain any duplicate elements.

Example:

Set<Integer> s = new Set<Integer>();
s.add(1);
s.add(1);
System.assert(s.size()==1);