JAVA

lambda expressions in java

A lambda expression is a short block 
of code which takes in parameters
and returns a value. Lambda expressions
are similar to methods, but they do
not need a name and they can be
implemented right in the body of a method.

parameter -> expression

To use more than one parameter, wrap them in parentheses:

(parameter1, parameter2) -> expression

Example
Use a lamba expression in the ArrayList's 
forEach() method to print every item in the list:

import java.util.ArrayList;

public class Main {
  public static void main(String[] args) {
    ArrayList<Integer> numbers = new ArrayList<Integer>();
    numbers.add(5);
    numbers.add(9);
    numbers.add(8);
    numbers.add(1);
    numbers.forEach( (n) -> { System.out.println(n); } );
  }
}

lambda java

interface demoLambda{
void sayHello();
}
public class main(String[]args){
demoLambda(()->System.out.println("hello"));
}
public void demoLambda(demoLambda d){
d.sayhello();
}

java lambda expressions

//* No Parameter Syntax
() -> {  
//Body of no parameter lambda  
}

//* One Parameter Syntax
(p1) -> {  
//Body of single parameter lambda  
}  

lambda function java

There are few functional interfaces namely Consumer, Supplier, Predicate and Functions
- Consumer: 
  + 1 input, 0 output
  + java.util.function.Consumer
  + example: Consumer<List<String>> printConsumer = list -> list.stream().forEach(System.out::println);

- Supplier: 
  + 0 input, 1 output
  + java.util.function.Supplier
  + example: Supplier<Double> doubleSupplier1 = () -> Math.random();

- Predicate: 
  + 1 input, 1 boolean output
  + java.util.function.Predicate
  + example: Predicate<String> nameStartsWithS = str -> str.startsWith("S");

- Function: 
  + 1 input, 1 output
  + java.util.function.Function
  + example: Function<String, Integer> nameMappingFunction = String::length;

lambda expression java

public class TestLambda {

   public static void main(String args[]) {
      List<String> lowerCaseStringsList = Arrays.asList("a","b","c");
     // the :: notation is the lambda expression
     // it's the same as the anonymous function s -> s.toUpperCase()
      List<String> upperCaseStringsList = lowerCaseStringsList.stream().
        map(String::toUpperCase).
        collect(Collectors.toList());
   }   
}

how to use lambda in java

StateOwner stateOwner = new StateOwner();

stateOwner.addStateListener(
    (oldState, newState) -> System.out.println("State changed")
);

lambda function java

static int method(IntBinaryOperator op){
    return op.applyAsInt(5, 10);
}

how to use -> in java (Lambda Expression)

//The:
Runnable r = ()-> System.out.print("Run method");
//is equivalent to:
Runnable r = new Runnable() {
        @Override
        public void run() {
            System.out.print("Run method");
        }
};

java lambda

(par1, par2, ...) -> {do...}