org.op4j.functions.Get is a special functions class which allows the retrieval of attribute values through the execution of getter methods.
Here is an example: Imagine your application has a User class which contains a getName() method, returning a String. Let's get the names of all the users in a list:
List<User> users = ...;
List<String> userNames = Op.on(users).map(Get.attrOfString("name")).get();
The attrOfX(...) methods in the Get class return the following functions:
| Method | Returned function type |
| attrOfBigDecimal() | Function<Object,BigDecimal> |
| attrOfBigInteger() | Function<Object,BigInteger> |
| attrOfBoolean() | Function<Object,Boolean> |
| attrOfByte() | Function<Object,Byte> |
| attrOfCalendar() | Function<Object,Calendar> |
| attrOfCharacter() | Function<Object,Character> |
| attrOfDate() | Function<Object,Date> |
| attrOfDouble() | Function<Object,Double> |
| attrOfFloat() | Function<Object,Float> |
| attrOfInteger() | Function<Object,Integer> |
| attrOfLong() | Function<Object,Long> |
| attrOfObject() | Function<Object,Object> |
| attrOfShort() | Function<Object,Short> |
| attrOfString() | Function<Object,String> |
| attrOf(Type<T>) | Function<Object,T> |