Set class method ContainsAll not working for special character '-' in strings?

Question

Facing a weird issue I have spaces and hyphen in my set of strings and now doing at ContainsAll check but it always returns false. If I remove hyphen - between my strings data then it works?

Can someone please explain this behaviour why it doesn't treat same string in different sets differently?

Adding Execute Anonymous code :

Set<String> Broadbands = New Set<String>{'Supplementary–BroadbandNumberRange','Supplementary–BroadbandData','Supplementary–SIMDevice','Supplementary–BroadbandHandset','Broadband','CLP'};
Set<String> a = New Set<String>{'BroadbandNumberRange','BroadbandData','SIMDevice','BroadbandHandset','Broadband','Internet'};
Set<String> bask = New Set<String> {'Supplementary-BroadbandHandset', 'Supplementary-BroadbandNumberRange', 'Supplementary-SIMDevice', 'Broadband'};
Set<String> b= New Set<String> {'BroadbandHandset', 'BroadbandNumberRange', 'SIMDevice', 'Broadband'};

Never works

if(Broadbands.containsall(bask)){
    system.debug('yeah');
}

This works

if(a.containsall(b)){
    system.debug('hello');
}

Answer 1

For some reason, your editor decided to mix en-dash ("–") with hyphen ("-"). While they look similar, they are definitely not the same and produce different hashes. It's hard to see the difference in a monospace font, but hopefully they should look visually different in this answer (en-dash is significantly longer than hyphen). Always avoid copy-pasting code in to/out of "Office" editors like Microsoft Word, since they may mangle quotes, hyphens, and other punctuation.

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Set<String> Broadbands = New Set<String>{'Supplementary-BroadbandNumberRange','Supplementary-BroadbandData','Supplementary-SIMDevice','Supplementary-BroadbandHandset','Broadband','CLP'};
Set<String> a = New Set<String>{'BroadbandNumberRange','BroadbandData','SIMDevice','BroadbandHandset','Broadband','Internet'};
Set<String> bask = New Set<String> {'Supplementary-BroadbandHandset', 'Supplementary-BroadbandNumberRange', 'Supplementary-SIMDevice', 'Broadband'};
Set<String> b= New Set<String> {'BroadbandHandset', 'BroadbandNumberRange', 'SIMDevice', 'Broadband'};
System.assert(Broadbands.containsall(bask),'Hyphens should match correctly');
System.assert(a.containsall(b), 'Non-hyphens should match correctly');

Answer 2

Just by looking at your code, I can tell the strings in your Broadbands variable and bask are not same.

Broadbands consists of character – (en-dash) which you get in quite a few editors e.g., MS Word if you try putting two hyphens and separate words. The bask variable consists only of a - (hyphen).

You will get the desired results if you just copy paste the string values from Broadbands to bask or correct your string values to as desired.