Comparison operators

Preface – This post is part of the Core Apex Tools series.

We must understand comparison operators before moving on to IF statements! A comparison operator is simply any statement the equals a boolean (TRUE or FALSE).

Try to guess which of these are TRUE and which are FALSE!

Comparisons for Number and Date fields:

david.Weight__c < 150;                     
david.Weight__c >= marcBenioff.Weight__c;
// You need two equal signs (==) to test equality
david.Diet_Start_Date__c == Date.today();
david.Sleep_Hours__c == 5; 
// How to test inequality
david.Donuts_Eaten__c != 0;

Comparisons for Text and Picklist fields:

// Strings also use == and !=
david.Favorite_Food__c == 'Cheeseburgers';
david.Favorite_Food__c != 'Liver';

Comparisons for Checkbox fields:

// Checkbox fields are always either TRUE or FALSE!
david.Likes_Ice_Cream__c;
// The exclamation point (!) takes the opposite of the statement!
// I'm not training for a marathon, so this comes out to TRUE
!david.Training_for_Marathon__c;

Combine comparisons using || for OR, && for AND, and parentheses:

// Both of these are FALSE, so the outcome is FALSE
david.Weight__c < 150 || david.Training_for_Marathon__c;
// This is FALSE because I am lactose intolerant =(
david.Likes_Ice_Cream__c && !david.Is_Lactose_Intolerant__c;
// Combine ORs and ANDs using parentheses!
(david.Is_Hungry__c || david.Is_Bored__c) 
 && david.Has_Ice_Cream__c; 

Next post: IF statements!