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public class Calculator {
  
    interface IntegerMath {
        int operation(int a, int b);   
    }
  
    public int operateBinary(int a, int b, IntegerMath op) {
        return op.operation(a, b);
    }
 

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TODO

• kafkacat commands

some useful comands

start cluster locally with port forward or host network

docker run -d --name=landoop -p 127.0.0.1:8081-8083:8081-8083 -p 127.0.0.1:9581-9585:9581-9585 -p 127.0.0.1:9092:9092 -p 127.0.0.1:3030:3030 -p 127.0.0.1:2181:2181 -e ADV_HOST=127.0.0.1 landoop/fast-data-dev

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package com.golonzovsky.streams;

import lombok.AllArgsConstructor;
import lombok.Data;
import org.junit.Before;
import org.junit.Test;

import java.io.BufferedReader;
import java.io.FileReader;
import java.time.Year;

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Serialization

What serialization is?

If you take an object and serialize it, that means turning that object into binary form or binary data. De serialize means take binary data and turn it back into an object.

TODO Serialization example

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Stack and Heap

Recursion

The following code will generate an error

public class App {

	public static void main(String[] args) {
		int value = 4;
 calculate(value);

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String bulider and string formatting

?Every time you are putting a plus between two strings you are creating a new string.

In Java strings are immutable, once you create a string you can never change it. It looks like you changed it , but it's not true. You are creating a new string, you are not appending to the existing string.

StringBuilder

Use StringBuilder class instead. StringBuilder appends new content, it does not

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Scanner userinput = new Scanner(System.in);
int value; 
do{
	System.out.println("Enter an integer value: ");
	value = userinput.nextInt();
}while(value !=5);
System.out.println("Got 5!");

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//This is my note for Java Collection Framework course taught by John.  
//Original credit: John from caveofprogramming.com
//All of his videos can be found in youtube.com
/**---------------------------------
| 1. ArrayList 
|
*/---------------------------------

1. 
-ArrayList class implements the class that is expandable. 

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/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
//package oefs;

import java.util.Scanner;

/**

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import java.util.Formatter;
import java.util.Scanner;


public class CheckBTW{

	public static void main(String args[]){
	

		System.out.print("Geef een getal: ");