The following table describes the different data types available in APL. The second column states if the data type is a primitive, or an object. The third column indicates the default value that an uninitialized variable will obtain.

boolean aBool=true;

byte aNumber=127;

char aCharacter='a';

short aNumber=31000;

int aNumber=2147483640;

float aValue=0.5;

double aValue=432482943.1;

double POS_INFINITY=1.0/0.0;
double NEG_INFINITY=-1.0/0.0;

long aNumber=92233720368547;

bigint aNumber;

bigdec aNumber;

string aString = "foobar";
string mlString = """{
 "key1": "value 1",
 "key2": "value 2"
}""";

any aVar;
aVar = 1;
aVar = "foobar";

bitset aBitset;

bytearray anArray;

date aDate;

ipaddress anIp = ipLocalHost();

list<int> intList;

map<string, int> aMap =	
mapCreate(string, int);

table aTable = 
tableCreate("Default",
anSQL);

drudr anyUDR;

MyUDR udr = { 
   "field1": 42, 
   "field2": variable, 
   "field3": someHelpFunction() 
};

uuid u=uuidCreateRandom();

The variable types follow Java standard regarding object reference vs. value semantics. All types use value semantics when compared through the '==' and '!=' boolean operators and objects use reference semantics for all other operators, like assignments '='.

date myDate_A = dateCreateNow();
  date myDate_B = myDate_A;
  long myLong_A = 10;
  long myLong_B = myLong_A;

  if (myDate_A == myDate_B ) {
      // true
  }
  if (myLong_A == myLong_B) {
      // true
  }

  // Change value on A variables
  dateAddHours(myDate_A, 22);
  if (myDate_A == myDate_B) {
      // still true, points to same object
  }
  myLong_A = 55;
  if (myLong_A == myLong_B) {
      // false, primitives always hold their own values
  }

It is possible to cast between different types with regular Java syntax. The instanceOf function is used to evaluate dynamic types since an incorrect type conversion will cause the workflow to abort with a runtime error.

/* APL code for two UDR types */
consume {
   if( instanceOf( input, UDRType1 ) ) {
     UDRType1 udr1 = (UDRType1) input;
     // Handle UDRType1 ...
   } else {
     UDRType2 udr2 = (UDRType2) input;
     // Handle UDRType2 ...
   }
}

As an extension to the regular conversions, all types may be casted to string type.

Note that some types are subtypes of other types and can be directly assigned. Examples are:

• All types are subtypes of the any type.

• int is a subtype (narrowing) of long.

• All UDR types are subtypes of the general base type drudr.

• Some UDR types are subtypes of other UDR types (depending on Ultra definitions).

There is also a number of built-in type conversion functions (refer to the section below, Access of UDR Fields).

Access of UDR Fields

UDR fields are accessed with the '.' separator. For instance, to access the field myField within the UDR type variable theUDR, the syntax would be:

theUDR.myField = 5;
debug( theUDR.myField );

If the field name is a variable instead of a string, udrGetValue/udrSetValue can be used to set/get field values dynamically. 

Access of non-present fields will return the default value for the specific type. Field presence is evaluated with udrIsPresent.

When writing to a UDR field on a null object, a NullPointerException will be thrown, see example:

myUDR theUDR = null; 
int a = theUDR.myField // Will Not throw NullPointerException
theUDR.myField = 0; // Will throw NullPointerException

To  avoid exceptions, first make sure that the UDR is not a null object:

if( theUDR != null ) {
    theUDR.myField = 0;
}

For further information about UDR related functions, see UDR Functions(3.2).

Access of Input UDR

Within the consume block, the incoming UDR can be accessed using the special variable input. The instanceOf function may be useful in case of dealing with several UDR types. Refer to instanceOf in Type Comparison Functions(3.2).