Does exist on apex something like Class.getDeclaredFields?

I need to loop on class attributes dynamically :

public class MyClass
public type1 att1;
public type2 att2;
public void function()
    for(var in MyClass.Attributes)



MyClass m = new MyClass();

for(String key: MyClass.Attributes)

You can achieve this using JSON.serialize and JSON.deserialize, as described in my answer to this question: Can I tell which fields are present in an SObject variable?

Suppose you have a class MyClass, with two attributes att1 and att2. We then add a method getAttributes() to return a Set<String> containing the names of the attributes on that object:

public class MyClass
public String att1;
public Decimal att2;

public Set<String> getAttributes()
    // Serialize our Object into JSON
    String s = JSON.serialize(this);

    // Deserialize it back into a key/value map
    Map<String,Object> obj = 
        (Map<String,Object>) JSON.deserializeUntyped(s);

    // Return a Set of those fields present on our object
    return obj.keyset().clone();


Which can be used like so:

MyClass c = new MyClass();
Set<String> attrs = c.getAttributes();
// ==> {'att1','att2'}

To dynamically walk through the attribute values, I would probably leverage System.JSONParser, which would let you walk through the attributes in an object/class, and provide you with both the ability to obtain the value of the attribute, and its type:

MyClass c = new MyClass();
c.att1 = 'foobar';
c.att2 = 100.1;
String jsonContent = JSON.serialize(c);

// ==> '{"att1":"foobar","att2",100.1}';

JSONParser parser = 
// Advance to the start object marker.
// Advance to the next value.
JSONToken t = parser.nextValue();

// Get the JSON type of the current value / token, 
// which is an ENUM of valid JSON types
    // (see http://www.salesforce.com/us/developer/docs/apexcode/Content/apex_methods_system_jsonparser.htm)

    system.debug('got a floating point number!');
    Decimal decimalValue = parser.getDecimalValue();
} else if (t == JSONToken.VALUE_STRING){
    // Here, to determine advanced Apex object types,
    // you may have to apply some Regex or try/catch conversion
    String stringValue = parser.getText();
    if (stringValue.split('-').size()==3){
        // We have a Salesforce Date value
        Date dateValue = parser.getDateValue();
    } else {
       // and so on for other Apex primitives
       // that are stored in JSON as Strings.

no as of now, but vote for the idea 'Apex Reflection'


  • Seb, see my answer, this is indeed possible at present. – zachelrath Sep 16 '13 at 17:12
  • @zachelrath I agree, but you dont get the type of the attribute hence you'd have to test it potentially for each type. As an alternative you'd have to implement a method that returns a map that links the attribute name to its type – Seb Wagner Sep 16 '13 at 18:42
  • 1
    @Seb__Wagner Good point --- I have updated my answer to explain how you can use JSONParser to walk through the object. – zachelrath Sep 16 '13 at 21:51

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