[Promotion of Ruby comprehension (1)] When switching from Java to Ruby, first understand the difference.

――As the words "It's good to do Java first." "The first training you will learn after joining the company is Java.", I just went straight on that track. ――As an experienced and pretentious Java young writer, I finally decided to cry at Ruby, which is "easy and popular", a mirror of a spoiled engineer. ――However, even though it is "easy and popular," there may be some ridiculous tricks, and there is a lot of negligence. ――So, we will work on it with the two main objectives of “relieving anxiety” and “efficient learning” to get dressed.

Common point

--Platform independent

--Access specification → Public, protected, private can be used.

--Single inheritance → A class can only have one direct parent class.

--The parent class of all classes is the Object class

--Typed. → Java requires variable and method type declarations, whereas Ruby requires them. → Java is a statically typed language, while Ruby is a dynamically typed language.

→ For Java

String name = "nanashi";
int number = 50;

→ For Ruby

name = "nanashi"
number = 50

--The parentheses for the method call can be omitted.

String message = "hello";

→ For Ruby

message = "hello"
puts message.length

--Constant change → In Java, constants cannot be changed, but in Ruby, they can be changed.

→ For Java

static final String MESSAGE = "Hello";
static final String MESSAGE = "Hello World"; //error. Not changed.

→ For Ruby

MESSAGE = "Hello"
MESSAGE = "Hello World" #Warning only

--There is no basic data type. → Since everything is expressed as an object, methods can be executed for ordinary numerical values.

→ For Java

String number = new String(100);

→ For Ruby

number = 100.to_s

--Presence or absence of minimum class definition. → In Ruby, it can be executed without a class.

→ For Java

public class Test {
    public static void main(String[] args) {
        System.out.println("Hello World");

→ For Ruby

puts "Hello World"

--Symbols can be used in method names →! And? Can be used.

→ For Java

public class Main {
    public static void main(String[] args) throws Exception {
        //An error will occur.
    public static void sayHello!(){

→ For Ruby

class UserNumberCheck
    def userNumber?

number = UserNumberCheck.new
if number.userNumber?
    puts "that's correct."

--Abundance of libraries and development speed → Abundant convenient library called gem → The flow of version update is fast.


――This time, because of the difference between Java and Ruby, we used Java, which we have taken care of so far, as a starting point, and let ourselves instill the "easiness and ease of writing" of Ruby. ――I'm doing the unskilled "unpopular typical behavior" of "Is this not possible with Ruby?", And I will be distanced from all languages in the future. ――I find the light of hope in such a realization certain future and live a cheerful life, so I will continue to work on simple learning today.


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