Functional Programming With Java 简明教程

Constructor References

构造函数引用有助于指向构造函数方法。可以使用“::new”符号访问构造函数引用。

Constructor references help to point to Constructor method. A Constructor reference is accessed using "::new" symbol.

//Constructor reference
Factory vehicle_factory = Vehicle::new;

以下示例展示了从 Java 8 开始，构造函数引用在 Java 中的工作原理。

Following example shows how Constructor references works in Java 8 onwards.

interface Factory {
   Vehicle prepare(String make, String model, int year);
}

class Vehicle {
   private String make;
   private String model;
   private int year;

   Vehicle(String make, String model, int year){
      this.make = make;
      this.model = model;
      this.year = year;
   }

   public String toString(){
      return "Vehicle[" + make +", " + model + ", " + year+ "]";
   }
}

public class FunctionTester {
   static Vehicle factory(Factory factoryObj, String make, String model, int year){
      return factoryObj.prepare(make, model, year);
   }

   public static void main(String[] args) {
      //Constructor reference
      Factory vehicle_factory = Vehicle::new;
      Vehicle carHonda = factory(vehicle_factory, "Honda", "Civic", 2017);
      System.out.println(carHonda);
   }
}

Output

Vehicle[Honda, Civic, 2017]