What the f*ck, Apex?

A list of funny and tricky Apex examples

Inspired by wtfjs

📖Table of Contents

• ✍🏻 Notation
• 👀Examples
  • When a boolean is not a boolean
  • String compare is case-insensitive (except when it's not)
  • Object equals override
  • Shadowing System (global) classes
  • "Phantom" Inner Class Type Equivalency
  • List contains & indexOf is broken
  • final parameters "exist", but can be reassigned
  • Fulfilling Interface Contracts with Static Methods
  • Exceptions are "exceptional"
  • System can have ambiguous return types
  • Odd List Initialization bug
  • Local Scope Leak
  • Broken type inference for Set<>
  • String.Format with single quotes
  • Line continuation breaks for static method
  • Fun with Hashcodes
  • JSON Serialization
  • Generics (parameterized interfaces) exist, but you can't use them
  • Polymorphic Primitives
  • Invalid HTTP method: PATCH
• 🔧 Since Fixed
  • Mutating Datetimes
  • More hashcode fun
  • Initializing Abstract Classes

✍🏻 Notation

// -> is used to show the result of an expression. For example:

1 + 1; // -> 2

// > means the result of System.debug or another output. For example:

System.debug('hello, world!'); // > hello, world!

// ! Means a runtime exception was thrown:

Decimal d = 1 / 0; // ! Divide by 0

// ~ Code fails to compile:

Decimal d = 'foo'; // ~ Illegal assignment from String to Decimal

// is just a comment used for explanations. Example:

// Assigning a function to foo constant
Foo foo = new Foo();

👀Examples

When a boolean is not a boolean

Boolean b;
if(b!=true) system.debug('b is not true');   // > b is not true
if(b!=false) system.debug('b is not false'); // > b is not false
if(b){}                                      // ! Attempt to de-reference a null object

See Advanced Apex Programming in Salesforce for explanation.

String compare is case-insensitive (except when it's not)

String x = 'Abc';
String y = 'abc';
System.assert(x == y);
System.assertEquals(x, y); // ! Expected: Abc, Actual: abc

See explanation on StackExchange

Object equals override

Try to override the equals method on any class and you'll be greeted with a very unexpected compile error: @Override specified for non-overriding method.

However, just remove the override keyword and it compiles!

At first glance it might seem like this works, but it is in fact very broken :(

public class MyClass {
    public Boolean equals(Object other) {
        System.debug('Called my equals');
        return false;
    }
}

MyClass m = new MyClass();
Object o = new MyClass();

m.equals('a'); // > 'Called my equals'
o.equals('a'); // System.debug is never called :(

Source: Aidan Harding

Shadowing System (global) classes

Nothing prevents you from recreating a class with the same name of one that exists in the System (default) namespace.

public class Database {
  public static List<sObject> query(String qry) {
    System.debug(qry);
    return null;
  }
}

Running Database.query('foo') will call our new class (essentially overriding the Database methods)!?

The same principle also applies to standard SObjects:

public class Account { }

Account acc = new Account();
acc.AccountNumber = '123'; // ! Variable does not exist: AccountNumber

Source: Daniel Ballinger

"Phantom" Inner Class Type Equivalency

public class IExist{}
System.assertEquals(IExist.class, IExist.IDont.Class); // -> passes

Source: Kevin Jones

List contains & indexOf is broken

"Apex Log level" influences behavior

The easiest way to test this is by writing the output to an object field.

1. Replace accId with a dummy account
2. Open a dev console and set the log levels to Apex=Finest
3. Run the following code

Id accId = '0012F00000YIc48QAD';
Account acc = new Account(Id = accId);
List<Id> haystack = new List<Id>();
haystack.add('0012F00000YIc46QAD');
haystack.add(accId);
haystack.add('0012F00000YIc49QAD');
String debug = 'Index: ' + haystack.indexOf(needle) + ' Contains: '   + haystack.contains(needle);
acc.AccountNumber = debug;
update acc;

4. Open the account. You should see the AccountNumber equals Index: 1 Contains: true
5. Set log levels to Apex=None
6. Run the code again
7. Refresh the account. AccountNumber will now equal Index: -1 Contains: false

Apparently this is a known issue and it has been fixed. This test shows otherwise...

15 Char Id's don't work

Behind the scenes Salesforce seems to always convert 15 character Id's to 18.

Equivalency works as expected in most cases:

Id a15 = '0012F00000YIc48';
Id a18 = '0012F00000YIc48QAD';
System.assert(a15 == a18);

However, for the List contains & indexOf methods, it doesn't:

List<Id> idList = new List<Id>{
   '0012F00000YIc46',
   '0012F00000YIc48',
   '0012F00000YIc49'
};
System.debug(idList); //-> (0012F00000YIc46QAD, 0012F00000YIc48QAD, 0012F00000YIc49QAD)
System.debug(idList.indexOf('0012F00000YIc48')); // > -1
System.debug(idList.contains('0012F00000YIc48')); // > false

You can avoid this by first assigning the value you are checking to an Id type.

final parameters "exist", but can be reassigned

You won't find a reference to it in the docs, but the compiler does apparently allow final parameters. However, it doesn't actually to prevent reassignment of such parameters:

public void withFinalParam(final String iAmFinal){
  iAmFinal = 'just kidding'; //compiles
}

Source: Kevin Jones

Fulfilling Interface Contracts with Static Methods

This shouldn't work but it does. Apparently also works with batch.

public class StaticsAreCool implements Schedulable{
   public static void execute(SchedulableContext sc){
   }
}

Source: Kevin Jones

Exceptions are "exceptional"

In their naming conventions:

public class OhGodBees extends Exception{}
// ~ Classes extending Exception must have a name ending in 'Exception'

and their Constructors:

public class BeesException extends Exception{
    public BeesException(){}
}
// ~ System exception constructor already defined: <Constructor>()

For explanation and further interesting observations, see Chris Peterson's blog post.

System can have ambiguous return types

Database.query is one of many cases where the Salesforce System namespace doesn't play by its own rules. It can return either a List<SObject> or a single SObject. No casting required.

Foo__c foo = Database.Query('SELECT Id FROM Foo__c');
List<Foo__c> foos = Database.Query('SELECT Id FROM Foo__c');

Try writing your own method to do this and you'll get an error:

Method already defined: query SObject Database.query(String) from the type Database (7:27)

You can overload arguments, but not return type.

Odd List Initialization bug

The initialization syntax for List<T> expects T ... args.

So obviously, if you passed a List<T> into it, you will get compile error:

List<Task>{new List<Task>()}; // ~ Initial expression is of incorrect type, expected: Task but was: List<Task>

Except, if List comes from new Map<Id,T>().values()...

The following code compiles without issue!

new List<Task>{new Map<Id,Task>().values()};

To add to the perplexity, when executed you will receive the following runtime error:

System.QueryException: List has no rows for assignment to SObject

Source: Matt Bingham

Local Scope Leak

If you write an If/Else without braces, symbols scoped in the "if" seem to leak into the "else":

if(false)
   String a = 'Never going to happen.';
else
   a = 'I should not compile';

Worth noting that Java won't even allow you to declare a block scoped variable inside a "braceless IF" as it can never be referenced elsewhere.

Source: Kevin Jones

Broken type inference for Set<>

Let's take a look at the standard Set class...

It can be iterated in a foreach loop:

Set<String> mySet = new Set<String>{'a', 'b'};
for(String s : mySet){}

But, according to Salesforce (compiler & runtime), it does not actually implement the Iterable interface:

String.join(mySet, ','); // ~ "Method does not exist or incorrect signature: void join(Set<String>, String)..."

// Just to make sure, lets check at runtime..
System.debug(mySet instanceof Iterable<String>);  // > false

Except... It actually does:

String.join((Iterable<String>) mySet, ','); // this works!?

Vote to fix this

String.Format with single quotes

String who = 'World';
String msg = String.format(
     'Hello, \'{0}\'',
     new List<String>{who}
);
System.assert(msg.contains(who)); // ! assertion failed

Unexpectedly, msg is set to Hello, {0}

🤔

To get this to work properly you must escape two single quotes:

String who = 'World';
String msg = String.format(
     'Hello, \'\'{0}\'\'',
     new List<String>{who}
);
System.assert(msg.contains(who)); // -> passes

Explanation by Daniel Ballinger

Line continuation breaks for static method

In apex, all statements must be terminated by a ;. This allows statements to span multiple lines:

Order o = new OrderBuilder()
  .addLineItem('foo', 5)
  .addLineItem('bar', 10)
  .setDiscount(0.5)
  .toOrder();

However, for some reason if the method is static, apex doesn't let it span a newline:

Order o = OrderBuilder
  .newInstance() // ~ Variable does not exist: OrderBuilder
  .addLineItem('foo', 5)
  .addLineItem('bar', 10)
  .setDiscount(0.5)
  .toOrder();

Source: Leo Alves

Fun with Hashcodes

Enums in batch

Objects in hashcodes

JSON Serialization

1. There's no way to control automatic serialization of object properties (like [JsonProperty(PropertyName = "FooBar")] in C#)
2. There are reserved keywords that you can't use as property names.

Meaning the following cannot be parsed or generated using JSON.deserialize or JSON.serialize:

{
  "msg": "hello dingus",
  "from": "Dr. Dingus"
}

Work-around

Generics (parameterized interfaces) exist, but you can't use them

Once upon a time, generics were actually part of Apex. However, they have since been removed (with the exception of system classes (List<>, Batchable<>, etc).

Why would you want generics when your OS has perfectly good Copy & Paste functionality built right into it?

Vote for Generics

Polymorphic Primitives

Object x = 42;
System.debug(x instanceOf Integer); // > true
System.debug(x instanceOf Long);    // > true
System.debug(x instanceOf Double);  // > true
System.debug(x instanceOf Decimal); // > true

Source: Daniel Ballinger

Invalid HTTP method: PATCH

When you try this:

Http h = new Http();
HttpRequest req = new HttpRequest();
req.setEndpoint('hooli.com');
req.setMethod('PATCH');
HttpResponse res = h.send(req); // ! Invalid HTTP method: PATCH

There is a workaround, but only supported by some servers.

🔧 Since Fixed

Thankfully, these WTF's have since been fixed by Salesforce. We'll keep them documented for historical purposes (and entertainment).

Mutating Datetimes

https://twitter.com/FishOfPrey/status/869381316105588736

More hashcode fun

https://twitter.com/FishOfPrey/status/1016821563675459585

https://salesforce.stackexchange.com/questions/224490/bug-in-list-contains-for-id-data-type

Initializing Abstract Classes

Resolved in Spring '20 by the "Restrict Reflective Access to Non-Global Controller Constructors in Packages" Critical Update

public abstract class ImAbstract {
    public String foo;
}

ImAbstract orAmI = (ImAbstract) JSON.deserialize('{"foo":"bar"}', ImAbstract.class);
System.debug(orAmI.foo); // > bar

See Stack Exchange Post