Java 8 — BiFunction | Code Factory

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Normal Function can take only one input argument and perform required operation and returns the result. The result need not be boolean type.

But sometimes our programming requirement to accept 2 input values and perform required operation and should return the result. Then we should go for BiFunction.

BiFunction is exactly same as funtion except that it will take 2 input arguments.

@FunctionalInterface
public interface BiFunction<T,U,R> {
    R apply(T t, U u);
    default <V> BiFunction<T,U,V> andThen(Function<? super R,? extends V> after) { }
}

To find product of 2 given integers by using BiFunction :

package com.codeFactory.bifunction;
import java.util.function.BiFunction;
public class Test {
 public static void main(String... args) {
  BiFunction<Integer, Integer, Integer> f = (a, b) -> a * b;
  System.out.println(f.apply(10, 20));
  System.out.println(f.apply(7, 10));
 }
}

Output :

200
70

Create Student Object by taking name and rollno as input by using BiFunction :

package com.codeFactory.bifunction;
import java.util.ArrayList;
import java.util.function.BiFunction;
class Student {
 String name;
 int rollno;
 
 Student(String name, int rollno) {
  this.name = name;
  this.rollno = rollno;
 }
@Override
 public String toString() {
  return "Student [name=" + name + ", rollno=" + rollno + "]";
 }
}
public class Test {
 public static void main(String... args) {
  ArrayList<Student> i = new ArrayList<Student>();
  BiFunction<String, Integer, Student> f = (name, rollno) -> new Student(name, rollno);
  
  i.add(f.apply("Narendra", 1));
  i.add(f.apply("Amit", 2));
  i.add(f.apply("Yogi", 3));
  i.add(f.apply("Nitin", 4));
  
  for(Student s : i) {
   System.out.println(s);
  }
 }
}

Output :

Student [name=Narendra, rollno=1]
Student [name=Amit, rollno=2]
Student [name=Yogi, rollno=3]
Student [name=Nitin, rollno=4]

Calculate Monthly Salary with Employee and TimeSheet objects as input By using BiFunction :

package com.codeFactory.bifunction;
import java.util.function.BiFunction;
class Employee {
 int eno;
 String name;
 double dailyWage;
 
 Employee(int eno, String name, double dailyWage) {
  this.eno = eno;
  this.name = name;
  this.dailyWage = dailyWage;
 }
}
class TimeSheet {
 int eno;
 int days;
 
 TimeSheet(int eno, int days) {
  this.eno = eno;
  this.days = days;
 }
}
public class Test {
 public static void main(String... args) {
  BiFunction<Employee, TimeSheet, Double> f = (e, t) -> e.dailyWage * t.days;
  Employee e = new Employee(1, "Narendra", 3000);
  TimeSheet t = new TimeSheet(1, 20);
  System.out.println("Monthly Salary : " + f.apply(e, t));
 }
}

Output :

Monthly Salary : 60000.0