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How to implement a constructor reference with one or more arguments in Java?
A method reference can also be applicable to constructors in Java 8. A constructor reference can be created using the class name and a new keyword. The constructor reference can be assigned to any functional interface reference that defines a method compatible with the constructor.
Syntax
<Class-Name>::new
Example of Constructor Reference with One Argument
import java.util.function.*;
@FunctionalInterface
interface MyFunctionalInterface {
Student getStudent(String name);
}
public class ConstructorReferenceTest1 {
public static void main(String[] args) {
MyFunctionalInterface mf = Student::new;
Function<Sttring, Student> f1 = Student::new; // Constructor Reference
Function<String, Student> f2 = (name) -> new Student(name);
System.out.println(mf.getStudent("Adithya").getName());
System.out.println(f1.apply("Jai").getName());
System.out.println(f2.apply("Jai").getName());
}
}
// Student class
class Student {
private String name;
public Student(String name) {
this.name = name;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}Output
Adithya Jai Jai
Example of Constructor Reference with Two Arguments
import java.util.function.*;
@FunctionalInterface
interface MyFunctionalInterface {
Student getStudent(int id, String name);
}
public class ConstructorReferenceTest2 {
public static void main(String[] args) {
MyFunctionalInterface mf = Student::new; // Constructor Reference
BiFunction<Integer, String, Student> f1 = Student::new;
BiFunction<Integer, String, Student> f2 = (id, name) -> new Student(id,name);
System.out.println(mf.getStudent(101, "Adithya").getId());
System.out.println(f1.apply(111, "Jai").getId());
System.out.println(f2.apply(121, "Jai").getId());
}
}
// Student class
class Student {
private int id;
private String name;
public Student(int id, String name) {
this.id = id;
this.name = name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}Output
101 111 121
Updated on: 14-Jul-2020
5K+ Views
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