How to implement Lambda expression in Apex

Question

I have this below interface in Java

public interface DoubleOperator {

    double applyAsDouble(double left, double right);
}

And below implementing it using Lambda -

DoubleOperator [] ops = {
(a, b) -> a + b,
(a, b) -> a - b
};

How we can implement this in Apex . Any suggestions. Like using Inferface in Apex

Answer 1

Lambdas don't exist in Apex. You can use interfaces, but you still have to write out the entire class:

 public interface DoubleOperator {
   double applyAsDouble(double left, double right);
 }
 public class AddDoubleOperator implements DoubleOperator {
   double applyAsDouble(double left, double right) {
     return left + right;
   }
 }
 public class SubtractDoubleOperator implements DoubleOperator {
   double applyAsDouble(double left, double right) {
     return left - right;
   }
 }
 DoubleOperator[] ops = new DoubleOperator[] {
   new AddDoubleOperator(), new SubtractDoubleOperator()
 };

While it'd be nice to have lambdas, that's just not something we can do today in Apex.