Lambda Expression - amresh087/newronaRepos GitHub Wiki

This concept come from lambda calculus

Lamda Programming

• Enable functional programming in java
• Write more readable, maintainable and concise code(very less code)
• To use api very easily and effectively
• To Enable parallel process also

Different between anonymous Inner class and Lamda Expression

1. Anonymous class is class without name Lamda Expression is function without function name(anonymous function)

2. Anonymous class can extend abstract or concrete class Lamda expression can not extend abstract or concrete class

3. Anonymous class can implements any num of interface Lamda expression can implements one interface that contain one abstract method

4. Inside Anonymous class you can declare instance variable but inside Lamda expression can not declare instance variable what ever declare variable that is consider local only.

5. Inside Anonymous class is best uses if interface contain multiple method Lamda expression is best if interface contain one method only.

    package com.amresh.functional;
   
    interface interf {
      void m1();
       }
   
   public class LamdaExample {
   
   int x = 10;
   
   void m2() {
   		int y = 20;
   
   	interf itf = () -> {
   		
   		System.out.println(x);
   		System.out.println(y);
                           x=333; //this vaild becuase class level variable
                           y=99; //invaild becuase method leve or local variable
   
   
   	};
   
   	itf.m1();
   
   }
   
   public static void main(String[] args) {
   
   	LamdaExample le = new LamdaExample();
   	le.m2();
   
                 Thread t=new Thread(()->{
   		
   		for(int i=0;i<10;i++)
   		{
   			System.out.println(i);
   		}
   	});
   	
   	t.start();
   
   
   
   }
   
   }
   

Note--> Here y = 20 is treated as final

Local variable of method which are reference from lamda expression are final. you can not change value of y in lamda expression

Note--> The main concept in Lamda expression you can assign function as value in interface. So you can say lamda express pass as argument in method or constructor.

for example

       String s="amresh"; //this store value
       interf itf = () -> {....} // here can see interface store 
       Thread t1=new Thread(
                             ()->{
                                   for(int i=0;i<=10;i++)
                                       System.ou.println(i);  

                                  };
                             );

Zero parameter:

() -> System.out.println("Zero parameter lambda");

One parameter:

(p) -> System.out.println("One parameter: " + p);

Multiple parameters :

(p1, p2) -> System.out.println("Multiple parameters: " + p1 + ", " + p2);