Dictionary.ContainsKey never finds a key (using a collection Initializer)

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I have a dictionary with a intilizer collection. I want to use that as my key but it never founds them in my dic MAP_ALARMS when I do the check. Why? what is wrong in my code? I also tried storing first the AlarmMapped objcts in a

C#

List<AlamrMapped> mapList

and then use as keys of my dictionary mapList[0],mapList[1].. but still , it never finds any key matching.Whats the problem?

C#

public class AlarmMapped
    {
        public string SubsystemId { get; set; }
        public string Code { get; set; }
        public string SystemId { get; set; }
        public AlarmMapped(string systemId, string subsystemId, string subsystemCode)
        {
            SystemId = systemId;
            SubsystemId = subsystemId;
            Code = subsystemCode;
        }
}

public Dictionary<AlarmMapped, string> MAP_ALARMS = new Dictionary<AlarmMapped, string>()
       {
        {  new AlarmMapped ("SYSTEM_STERRING","SUBSYSTEM_STERRING_POWERUNIT","004"),"Phase Fail"},
        {  new AlarmMapped ("SYSTEM_STERRING","SUBSYSTEM_STERRING_POWERUNIT","005"),"Hydraulic fluid level"},

       };

public void myFunction(){

CheckMap(new AlarmMapped("SYSTEM_STERRING","SUBSYSTEM_STERRING_POWERUNIT","005");
}

public void CheckMap(AlarmMapped m){

if(MAP_ALARMS.ContainsKey(m)){

......
}
}

Posted 27-Aug-15 23:55pm

Kinna-10626331

Updated 27-Aug-15 23:56pm

v2

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CPallini · Accepted Answer · 2015-08-28T00:18:00

Solution 1

You are comparing references to objects (they cannot be equal for differenct objects, even if they contain same data).
See here: "Comparing object used as Key in Dictionary"[^].

Posted 28-Aug-15 0:18am

CPallini

Comments

Sergey Alexandrovich Kryukov 28-Aug-15 10:43am

5ed.
—SA

OriginalGriff · Accepted Answer · 2015-08-28T00:18:00

Um.
AlarmMapped is a class, which means that your Dictionary consists of a reference to a class instance, and a reference to a string.
So any checking against the dictionary keys to find a matych will compare class references, not class content.
So if your dictionary contains these elements:

C#

public Dictionary<AlarmMapped, string> MAP_ALARMS = new Dictionary<AlarmMapped, string>()
       {
        {  new AlarmMapped ("SYSTEM_STERRING","SUBSYSTEM_STERRING_POWERUNIT","004"),"Phase Fail"},
        {  new AlarmMapped ("SYSTEM_STERRING","SUBSYSTEM_STERRING_POWERUNIT","005"),"Hydraulic fluid level"},

       };

And you check it against a new instance of your class:

C#

CheckMap(new AlarmMapped("SYSTEM_STERRING","SUBSYSTEM_STERRING_POWERUNIT","005");

you will be checking to see if the new instance reference exists in the dictionary - which by definition it won't because it is a new instance, even if it contains the same data.

It's like putting your mobile phone in your desk drawer, and then expecting to find your contacts and messages in a phone you found in my desk drawer!