Set contain only last element on calling add function

Question

i wrote a function which uses set.my function is

public static Set<Schema.DisplayType> giveSchemaSet(Set<String> x){
  Set<Schema.DisplayType> displayCompatibleSet = new Set<Schema.DisplayType>();
  Map<String,Schema.DisplayType> displayTypeMap = new Map<String,Schema.DisplayType>{
            'boolean' => Schema.DisplayType.Boolean,
            'currency' => Schema.DisplayType.Currency,
            'date' => Schema.DisplayType.Date,
            'datetime' => Schema.DisplayType.DateTime,
            'double' => Schema.DisplayType.Double,
            'email' => Schema.DisplayType.Email,
            'encryptedstring' => Schema.DisplayType.EncryptedString,
            'integer' => Schema.DisplayType.Integer,
            'multipicklist' => Schema.DisplayType.MultiPickList,
            'percent' => Schema.DisplayType.Percent,
            'phone' => Schema.DisplayType.Phone,
            'picklist'=> Schema.DisplayType.Picklist,
            'reference'=>Schema.DisplayType.Reference,
            'string' =>Schema.DisplayType.String,
            'textarea' =>Schema.DisplayType.TextArea,
            'time' => Schema.DisplayType.Time,
            'url' => Schema.DisplayType.URL
            };
  System.debug('x is '+x);
  for(String displayType:x)
  {
   System.debug('displayType is:' + displayTypeMap.get(displayType));
   displayCompatibleSet.add(displayTypeMap.get(displayType));
  }
  System.debug('displayCompatibleSet is'+displayCompatibleSet);
  return displayCompatibleSet;
}

in debug log

x is {boolean, picklist, string, textarea}
displayCompatibleSet is{BOOLEAN}

in argument i am passing 4 elements but in displayCompatibleSet.it should also be of 4 length but it contains only one element .can anyone please explain this behaviour.

Answer 1

With exactly the implementation you have posted this test passes so I think the code is good:

@isTest
private class ATest {
    @isTest
    static void test() {
        Set<String> x = new Set<String>{
                'boolean',
                'picklist',
                'string',
                'textarea'
                };
        Set<Schema.DisplayType> expected = new Set<Schema.DisplayType>{
                Schema.DisplayType.Boolean,
                Schema.DisplayType.Picklist,
                Schema.DisplayType.String,
                Schema.DisplayType.TextArea
                };
        System.assertEquals(expected, giveSchemaSet(x));
    }
    public static Set<Schema.DisplayType> giveSchemaSet(Set<String> x) {
        ...
    }
}

PS The issue is with the debug output of sets of enumerations: the sets themselves are fine.