package javaFeatures;

import java.util.Date;
import java.util.GregorianCalendar;
import java.util.function.BinaryOperator;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.Supplier;

public class MethodReferences {
 
 public int add(int a, int b) {
        return a + b;
    }
 
    public int mul(int a, int b) {
        return a * b;
    }
 
    public String lower(String a) {
        return a.toLowerCase();
    }
 
    public void printDate(Date date) {
        System.out.println(date);
    }
   
    public static boolean check(int value) {
     if(value > 100) {
      System.out.println("Value is greater than 100...");
      return true;
     }
     else {
      System.out.println("Value is lesser than 100...");
      return false;
     }
    }
   
    public void predicating(Predicate<Integer> pred, int a) {
     System.out.println("Before usage of Predicate with changed value...");
     a = 200;
     pred.test(a);
    }
 
    public void operBinary(BinaryOperator<Integer> operator, int a, int b) {
     System.out.println("About to apply the opration with changed values...");
     a = 5;
     b = 6;
        System.out.println(operator.apply(a, b));
    }
 
    public void operS(Function<String, String> stringOperator, String a) {
        System.out.println(stringOperator.apply(a));
    }
 
    public String operC(Supplier<GregorianCalendar> supplier) {
        return "Current date applied : " + supplier.get().getTime();
    }

   
    /**
     * In Below method both ways are shown, method reference & lambda expression
     */
    public static void main(String[] args) {
     MethodReferences mr = new MethodReferences();
     mr.operBinary((a, b) -> mr.mul(a, b), 1, 3);
//     mr.predicating((a) -> mr.check(a), 10);
     mr.predicating(MethodReferences::check, 10);
//     mr.operS(s -> s.toLowerCase(), "HELLO");
     mr.operS(mr::lower, "HELLO");
//     System.out.println(mr.operC(() -> new GregorianCalendar()));
     System.out.println(mr.operC(GregorianCalendar::new));
 }

}