Salesforce Primitive Data Types(dataTypes allowed in apex)

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();

12. sObject - Salesforce object (Custom or Standard)
Example : List<sObject> obj = new List<sObject>();

Collections
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1. List
2. Set
3. Map