Java Lambda expressions[How to filter the personList - startswith] | Lambda expression in Java

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Person.java

public class Person
{
    private String name;
    private int age;

    public Person(String name, int age)
    {
        super();
        this.name = name;
        this.age = age;
    }

    public String getName()
    {
        return name;
    }

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

    public int getAge()
    {
        return age;
    }

    public void setAge(int age)
    {
        this.age = age;
    }

    @Override
    public String toString()
    {
        return "Person [name=" + name + ", age=" + age + "]";
    }

}

LambdaDemo.java

import java.util.Arrays;
import java.util.List;

public class LambdaDemo
{
    public static void main(String[] args)
    {

        List<Person> personList = Arrays.asList(new Person("Carla", 33),
                new Person("Balu", 32), new Person("Bharth", 40),
                new Person("Ajay", 31));

        personList.stream().filter(person -> person.getName().startsWith("B"))
                .forEach(person -> System.out.println(person));
    }

}

Output

Person [name=Balu, age=32]
Person [name=Bharth, age=40]

Click the below link to download the code:
https://sites.google.com/site/ramj2eev1/home/javabasics/LambdaDemo_filter_list_person_startswith_app.zip?attredirects=0&d=1

Github Link:
https://github.com/ramram43210/Java/tree/master/BasicJava/LambdaDemo_filter_list_person_startswith_app

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/b58cad09932cc81678f7144749cb560485c5bdd8/BasicJava/LambdaDemo_filter_list_person_startswith_app/?at=master

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Java Lambda expressions[forEach method of List - Person] | Lambda expression in Java

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Java Lambda expressions[forEach method of List - Person] | Lambda expression in Java 

Person.java

public class Person
{
    private String name;
    private int age;

    public Person(String name, int age)
    {
        super();
        this.name = name;
        this.age = age;
    }

    public String getName()
    {
        return name;
    }

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

    public int getAge()
    {
        return age;
    }

    public void setAge(int age)
    {
        this.age = age;
    }

    @Override
    public String toString()
    {
        return "Person [name=" + name + ", age=" + age + "]";
    }

}

LambdaDemo.java

import java.util.Arrays;
import java.util.List;

public class LambdaDemo
{
    public static void main(String[] args)
    {

        List<Person> personList = Arrays.asList(
                new Person("Carla", 33), new Person("Balu", 32),
                new Person("Bharth", 40), new Person("Ajay", 31));
        
        
        System.out.println("---------- With out lambda-----------------");
        /*
         * Before JDK 8, With out lambda
         */
        for (Person person : personList)
        {
            System.out.println(person);
        }
        
        System.out.println("\n----------With lambda-----------------");

        /*
         * Now JDK 8 , With lambda
         */
        personList.forEach(person -> System.out.println(person));
        
        System.out.println("\n----------Method Reference-------------");
        
        /*
         * Method Reference
         */
        personList.forEach(System.out::println);
        
    }

}

Output

---------- With out lambda-----------------
Person [name=Carla, age=33]
Person [name=Balu, age=32]
Person [name=Bharth, age=40]
Person [name=Ajay, age=31]

----------With lambda-----------------
Person [name=Carla, age=33]
Person [name=Balu, age=32]
Person [name=Bharth, age=40]
Person [name=Ajay, age=31]

----------Method Reference-------------
Person [name=Carla, age=33]
Person [name=Balu, age=32]
Person [name=Bharth, age=40]
Person [name=Ajay, age=31]

Refer

https://docs.oracle.com/javase/8/docs/api/index.html?java/lang/Iterable.html

Click the below link to download the code:
https://sites.google.com/site/ramj2eev1/home/javabasics/LambdaDemo_list_foreach_person_app.zip?attredirects=0&d=1

Github Link:
https://github.com/ramram43210/Java/tree/master/BasicJava/LambdaDemo_list_foreach_person_app

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/4c13bd19ff03c6acdc5e87d7803290d625ce640a/BasicJava/LambdaDemo_list_foreach_person_app/?at=master

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Java Tutorial: Lambda expression in java | Java Lambda expressions[forEach method of List]

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Java Tutorial: Lambda expression in java | Java Lambda expressions[forEach method of List] 

LambdaDemo1.java

import java.util.ArrayList;
import java.util.List;

public class LambdaDemo1
{

    public static void main(String[] args)
    {

        List<String> nameList = new ArrayList<>();
        nameList.add("Peter");
        nameList.add("John");
        nameList.add("Juli");
        nameList.add("Stephan");

        /*
         * Before Java 8, Normal way to loop a list.
         */
        for (String name : nameList)
        {
            System.out.println(name);
        }

        System.out.println("------------------------------------");

        /*
         * In Java 8, we can loop a List with forEach + lambda
         * expression or method reference.
         */
        nameList.forEach(name -> System.out.println(name));

    }

}

Output

Peter
John
Juli
Stephan
------------------------------------
Peter
John
Juli
Stephan

LambdaDemo2.java

import java.util.ArrayList;
import java.util.List;

public class LambdaDemo2
{

    public static void main(String[] args)
    {

        List<String> nameList = new ArrayList<>();
        nameList.add("Peter");
        nameList.add("John");
        nameList.add("Juli");
        nameList.add("Stephan");

        /*
         * In Java 8, we can loop a List with forEach + lambda
         * expression or method reference.
         */

        nameList.forEach(name -> {
            if ("John".equals(name))
            {
                System.out.println("Hello " + name);
            }
        });
    }

}

Output

Hello John

LambdaDemo3.java

import java.util.ArrayList;
import java.util.List;

public class LambdaDemo3
{

    public static void main(String[] args)
    {

        List<String> nameList = new ArrayList<>();
        nameList.add("Peter");
        nameList.add("John");
        nameList.add("Juli");
        nameList.add("Stephan");

        /*
         * In Java 8, we can loop a List with forEach + lambda
         * expression or method reference.
         */

        //method reference
        nameList.forEach(System.out::println);
    }

}

Output

Peter
John
Juli
Stephan

LambdaDemo4.java

import java.util.ArrayList;
import java.util.List;

public class LambdaDemo4
{

    public static void main(String[] args)
    {

        List<String> nameList = new ArrayList<>();
        nameList.add("Peter");
        nameList.add("John");
        nameList.add("Juli");
        nameList.add("Stephan");

        /*
         * In Java 8, we can loop a List with forEach + lambda
         * expression or method reference.
         */

        //Stream and filter
        nameList.stream()
            .filter(name->name.contains("Juli"))
            .forEach(System.out::println);
    }

}

Output

Juli

Refer 
https://docs.oracle.com/javase/8/docs/api/index.html?java/lang/Iterable.html

Click the below link to download the code:
https://sites.google.com/site/ramj2eev1/home/javabasics/LambdaDemo_list_foreach_app.zip?attredirects=0&d=1

Github Link:
https://github.com/ramram43210/Java/tree/master/BasicJava/LambdaDemo_list_foreach_app

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/4c13bd19ff03c6acdc5e87d7803290d625ce640a/BasicJava/LambdaDemo_list_foreach_app/?at=master

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Java Tutorial: Lambda expression in java | Java Lambda expressions[forEach method of Map]

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Java Tutorial: Lambda expression in java | Java Lambda expressions[forEach method of Map] 

LambdaDemo1.java

import java.util.LinkedHashMap;
import java.util.Map;

public class LambdaDemo1
{

    public static void main(String[] args)
    {

        Map<Integer, String> map = new LinkedHashMap<>();
        map.put(1, "Peter");
        map.put(2, "John");
        map.put(3, "Juli");
        map.put(4, "Stephan");

        /*
         * Normal way to loop a Map.Before Java 8
         */
        for (Map.Entry<Integer, String> entry : map.entrySet())
        {
            System.out.println("key : " + entry.getKey() + ", value : "
                                                           + entry.getValue());
        }

        System.out.println("------------------------------------");

        /*
         * In Java 8, we can loop a Map with forEach + lambda expression.
         */
        map.forEach((k, v) -> System.out.println("key : " + k + " value : " + v));

    }

}

Output

key : 1, value : Peter
key : 2, value : John
key : 3, value : Juli
key : 4, value : Stephan
------------------------------------
key : 1 value : Peter
key : 2 value : John
key : 3 value : Juli
key : 4 value : Stephan

LambdaDemo2.java

import java.util.LinkedHashMap;
import java.util.Map;

public class LambdaDemo2
{

    public static void main(String[] args)
    {

        Map<Integer, String> map = new LinkedHashMap<>();
        map.put(1, "Peter");
        map.put(2, "John");
        map.put(3, "Juli");
        map.put(4, "Stephan");

        /*
         * In Java 8, we can loop a Map with forEach + lambda
         * expression+multiple statements.
         */

        map.forEach((k, v) -> {
            System.out.println("key : " + k + " value : " + v);
            if ("John".equals(v))
            {
                System.out.println("Hello John");
            }
        });
    }

}

Output

key : 1 value : Peter
key : 2 value : John
Hello John
key : 3 value : Juli
key : 4 value : Stephan

Refer:
https://docs.oracle.com/javase/8/docs/api/index.html?java/util/Map.html

Click the below link to download the code:
https://sites.google.com/site/ramj2eev1/home/javabasics/LambdaDemo_map_foreach_app.zip?attredirects=0&d=1

Github Link:
https://github.com/ramram43210/Java/tree/master/BasicJava/LambdaDemo_map_foreach_app

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/4c13bd19ff03c6acdc5e87d7803290d625ce640a/BasicJava/LambdaDemo_map_foreach_app/?at=master

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Lambda expression in java [How to implement the Functional interface - GreetingService]

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https://www.youtube.com/watch?v=91sd5c23Eoo&list=UUhwKlOVR041tngjerWxVccw

LambdaDemo.java

@FunctionalInterface
interface GreetingService
{
    void sayMessage(String message);
}

public class LambdaDemo
{

    public static void main(String[] args)
    {

        // with parenthesis
        GreetingService greetService1 = message ->
                          System.out.println("Hello " + message);

        // without parenthesis
        GreetingService greetService2 = (message) -> 
                          System.out.println("Hello " + message);

        greetService1.sayMessage("Peter");
        greetService2.sayMessage("John");
    }

}

Output

Hello Peter
Hello John

Click the below link to download the code:
https://sites.google.com/site/ramj2eev1/home/javabasics/LambdaDemo_parenthesis_app.zip?attredirects=0&d=1

Github Link:
https://github.com/ramram43210/Java/tree/master/BasicJava/LambdaDemo_parenthesis_app

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/4c13bd19ff03c6acdc5e87d7803290d625ce640a/BasicJava/LambdaDemo_parenthesis_app/?at=master

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Lambda expression in java | Java Lambda expressions[Lambda expression example - Math Operation]

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https://www.youtube.com/watch?v=fOhA0LsU9zc&list=UUhwKlOVR041tngjerWxVccw

LambdaDemo.java

@FunctionalInterface
interface MathOperation
{
    int operation(int a, int b);
}

public class LambdaDemo
{

    public static void main(String[] args)
    {

        LambdaDemo lambdaDemo = new LambdaDemo();

        // with type declaration
        MathOperation addition = (int a, int b) -> a + b;

        // with out type declaration
        MathOperation subtraction = (a, b) -> a - b;

        // with return statement along with curly braces
        MathOperation multiplication = (int a, int b) -> {
            return a * b;
        };

        // without return statement and without curly braces
        MathOperation division = (int a, int b) -> a / b;

        System.out.println("10 + 5 = " + lambdaDemo.operate(10, 5, addition));

        System.out.println("10 - 5 = " + lambdaDemo.operate(10, 5, subtraction));
        
        System.out.println("10 x 5 = " + lambdaDemo.operate(10, 5, multiplication));
        
        System.out.println("10 / 5 = " + lambdaDemo.operate(10, 5, division));
    }

    private int operate(int a, int b, MathOperation mathOperation)
    {
        return mathOperation.operation(a, b);
    }

}

Output

10 + 5 = 15
10 - 5 = 5
10 x 5 = 50
10 / 5 = 2

Click the below link to download the code:
https://sites.google.com/site/ramj2eev1/home/javabasics/LambdaDemo_math_App.zip?attredirects=0&d=1

Github Link:
https://github.com/ramram43210/Java/tree/master/BasicJava/LambdaDemo_math_App

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/4c13bd19ff03c6acdc5e87d7803290d625ce640a/BasicJava/LambdaDemo_math_App/?at=master

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Lambda expression in java[How to filter the list of product using lambda expression and Streams]

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https://www.youtube.com/watch?v=dg5HiojPb8k&list=UUhwKlOVR041tngjerWxVccw

Product.java

class Product
{
    private int id;
    private String name;
    private float price;

    public Product(int id, String name, float price)
    {
        super();
        this.id = id;
        this.name = name;
        this.price = price;
    }

    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;
    }

    public float getPrice()
    {
        return price;
    }

    public void setPrice(float price)
    {
        this.price = price;
    }

}

LambdaDemo.java

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Stream;

/**
 * Java Lambda Expression Example: Filter Collection Data
 *
 */
public class LambdaDemo
{

    public static void main(String[] args)
    {
        List<Product> list = new ArrayList<Product>();

        // Adding Products
        list.add(new Product(1, "Sony LED TV", 60000f));
        list.add(new Product(2, "Radio", 3000f));
        list.add(new Product(3, "Laptop", 80000f));
        list.add(new Product(4, "Smart phone", 70000f));
        list.add(new Product(5, "Mouse", 1500f));

        /*
         * Using lambda to filter data
         */
        Stream<Product> filteredStream = list.stream()
                                       .filter(p -> p.getPrice() > 50000);

        /*
         * Using lambda to iterate through collection
         */
        filteredStream.forEach(product -> System.out.println(
                product.getName() + ": " + product.getPrice()));
    }

}

Output

Sony LED TV: 60000.0
Laptop: 80000.0
Smart phone: 70000.0

Click the below link to download the code:
https://sites.google.com/site/ramj2eev1/home/javabasics/LambdaDemo_filter_product_App.zip?attredirects=0&d=1

Github Link:
https://github.com/ramram43210/Java/tree/master/BasicJava/LambdaDemo_filter_product_App

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/4c13bd19ff03c6acdc5e87d7803290d625ce640a/BasicJava/LambdaDemo_filter_product_App/?at=master

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Java Lambda expressions[How to sort the list of product using lambda expression - Comparator]

Click here to watch in Youtube : 
https://www.youtube.com/watch?v=r8zFhM04L_A&list=UUhwKlOVR041tngjerWxVccw

Product.java

class Product
{
    private int id;
    private String name;
    private float price;

    public Product(int id, String name, float price)
    {
        super();
        this.id = id;
        this.name = name;
        this.price = price;
    }

    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;
    }

    public float getPrice()
    {
        return price;
    }

    public void setPrice(float price)
    {
        this.price = price;
    }

}

LambdaDemo.java

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

/**
 * Java Lambda Expression Example: Comparator
 *
 */
public class LambdaDemo
{

    public static void main(String[] args)
    {
        List<Product> list = new ArrayList<Product>();

        // Adding Products
        list.add(new Product(1, "Sony LED TV", 65000f));
        list.add(new Product(2, "Radio", 3000f));
        list.add(new Product(3, "Laptop", 150000f));

        System.out.println("Before Sorting .... \n");

        displayProductInfo(list);

        System.out.println("\nAfter Sorting ...\n");

        // implementing lambda expression
        Collections.sort(list, (p1, p2) -> {
            return p1.getName().compareTo(p2.getName());
        });

        displayProductInfo(list);
    }

    private static void displayProductInfo(List<Product> list)
    {
        for (Product p : list)
        {
            System.out.println(p.getId() + " " + p.getName() + " "
                    + p.getPrice());
        }
    }

}

Output

Before Sorting .... 

1 Sony LED TV 65000.0
2 Radio 3000.0
3 Laptop 150000.0

After Sorting ...

3 Laptop 150000.0
2 Radio 3000.0
1 Sony LED TV 65000.0

Click the below link to download the code:
https://sites.google.com/site/ramj2eev1/home/javabasics/LambdaDemo_product_sort_name_App.zip?attredirects=0&d=1

Github Link:
https://github.com/ramram43210/Java/tree/master/BasicJava/LambdaDemo_product_sort_name_App

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/a195090f4adc5a52ed7df4d076a2367bfb5b1fbe/BasicJava/LambdaDemo_product_sort_name_App/?at=master

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Lambda expression[How to filter the list of person using lambda expression - Predicate and Consumer]

Click here to watch in Youtube :
https://www.youtube.com/watch?v=GcHBJnaT5RY&list=UUhwKlOVR041tngjerWxVccw

Person.java

public class Person
{
    private String name;
    private int age;

    public Person(String name, int age)
    {
        super();
        this.name = name;
        this.age = age;
    }

    public String getName()
    {
        return name;
    }

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

    public int getAge()
    {
        return age;
    }

    public void setAge(int age)
    {
        this.age = age;
    }

    @Override
    public String toString()
    {
        return "Person [name=" + name + ", age=" + age + "]";
    }

}

LambdaPredicateConsumerDemo.java

import java.util.Arrays;
import java.util.List;
import java.util.function.Consumer;
import java.util.function.Predicate;

public class LambdaPredicateConsumerDemo
{
    public static void main(String[] args)
    {
        List<Person> personList = Arrays.asList(
                new Person("Carla", 33), new Person("Balu", 32),
                new Person("Bharth", 40), new Person("Ajay", 31));

        System.out.println("------------Name Starts with B---------");
        /*
         * Create a method that prints all people that have name
         * begins with B.
         */
        printNameBeginWith_B(personList,
                p -> p.getName().startsWith("B"),
                p -> System.out.println(p));

        System.out.println("----------------------------------------");

        printNameBeginWith_B(personList,
                p -> p.getName().startsWith("B"),
                p -> System.out.println(p.getName()));

        System.out.println("----------------------------------------");
        
        printNameBeginWith_B(personList,
                p -> p.getName().startsWith("B"),
                p -> System.out.println(p.getAge()));

    }

    private static void printNameBeginWith_B(List<Person> personList,
            Predicate<Person> predicate, Consumer<Person> consumer)
    {
        for (Person person : personList)
        {
            if (predicate.test(person))
            {
                consumer.accept(person);
            }
        }

    }

}

Output

------------Name Starts with B---------
Person [name=Balu, age=32]
Person [name=Bharth, age=40]
----------------------------------------
Balu
Bharth
----------------------------------------
32
40

Refer

https://docs.oracle.com/javase/8/docs/api/java/util/function/package-summary.html

https://docs.oracle.com/javase/8/docs/api/java/util/function/Predicate.html

https://docs.oracle.com/javase/8/docs/api/java/util/function/Consumer.html

Click the below link to download the code:
https://sites.google.com/site/ramj2eev1/home/javabasics/LambdaDemo_consumer_App.zip?attredirects=0&d=1

Github Link:
https://github.com/ramram43210/Java/tree/master/BasicJava/LambdaDemo_consumer_App

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/317a84d07ee35ecc7934d034a6ca38f552a21665/BasicJava/LambdaDemo_consumer_App/?at=master

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