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JAVA EXAMPLE PROGRAMS

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How to return lambda as an object?


A lambda expression is an instance of a functional interface, which is itself a subtype of Object.

This example shows how to retrieve lambda as an object.

package com.java2novice.lambda;

public class Employee {

	private String name;
	private String account;
	private Integer salary;

	public Employee(String name, String account, Integer salary) {
		super();
		this.name = name;
		this.account = account;
		this.salary = salary;
	}

	@Override
	public String toString() {

		return "name: "+ this.name +" | account: "+ this.account +" | salary: "+this.salary;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getAccount() {
		return account;
	}

	public void setAccount(String account) {
		this.account = account;
	}

	public Integer getSalary() {
		return salary;
	}

	public void setSalary(Integer salary) {
		this.salary = salary;
	}
}

package com.java2novice.lambda;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class LambdaAsObjectEx {

	public static void main(String a[]) {

		List<Employee> empList = new ArrayList<>();
		empList.add(new Employee("Nataraja G", "Accounts", 8000));
		empList.add(new Employee("Nagesh Y", "Admin", 15000));
		empList.add(new Employee("Vasu V", "Security", 2500));
		empList.add(new Employee("Amar", "Entertainment", 8500));

		LambdaAsObjectEx.sortInLambdaWay(empList);
	}

	public static void sortInLambdaWay(List<Employee> empList) {

		Comparator<Employee> cmpDesc = (Employee e1, Employee e2) -> e2.getSalary().compareTo(e1.getSalary());

		Collections.sort(empList, cmpDesc);

		System.out.println("<--- Sorted list with Lambda - DESC order --->");
		empList.forEach(emp->System.out.println(emp.toString()));

		Comparator<Employee> cmpAsc = (Employee e1, Employee e2) -> e1.getSalary().compareTo(e2.getSalary());
		Collections.sort(empList, cmpAsc);

		System.out.println("\n\n<--- Sorted list with Lambda - ASC order --->");
		empList.forEach(emp->System.out.println(emp.toString()));
	}
}

Output:
<--- Sorted list with Lambda - DESC order --->
name: Nagesh Y | account: Admin | salary: 15000
name: Amar | account: Entertainment | salary: 8500
name: Nataraja G | account: Accounts | salary: 8000
name: Vasu V | account: Security | salary: 2500


<--- Sorted list with Lambda - ASC order --->
name: Vasu V | account: Security | salary: 2500
name: Nataraja G | account: Accounts | salary: 8000
name: Amar | account: Entertainment | salary: 8500
name: Nagesh Y | account: Admin | salary: 15000
<< Previous Program 

Java-8 Lambda expression examples

  1. Lambda expression syntax example
  2. Lambda example with single method interface implementation.
  3. Comparator example with Lambda implementation.
  4. How to return lambda as an object?
Knowledge Centre
Can interface be final?
No. We can not instantiate interfaces, so in order to make interfaces useful we must create subclasses. The final keyword makes a class unable to be extended.
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About Author

I'm Nataraja Gootooru, programmer by profession and passionate about technologies. All examples given here are as simple as possible to help beginners. The source code is compiled and tested in my dev environment.

If you come across any mistakes or bugs, please email me to [email protected].

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Reference: Java™ Platform Standard Ed. 7 - API Specification | Java™ Platform Standard Ed. 8 - API Specification | Java is registered trademark of Oracle.
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