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Prasanth
Prasanth

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Random Quote Generator

Step:1
File -> String Starter Project -> Project name Random_Quote_Generator ->Type Maven -> Packaging Jar-> Next
Step:2
Add dependencies:-

  1. Spring Web
  2. Spring Dev Tools
  3. Thymeleaf then finish. If unfortunately you not add missed some dependencies that time your project pom.xml (Right click)-spring -> ADD startes -> next -> you can add missed dependencies -> Next -> select pom.xml -> finish,
  • spring web and Thymeleaf before we saw what and why, now we see spring Dev Tool.

What is Spring Boot DevTools?

  • Spring Boot DevTools is a development-ime tool that helps developer save time and increase productivity by automatically reloading the application when code changes are made.

  • work faster less effort,you do not need to stop and restart the app and again and again ,DevTool handle it , you can focus on writing code ,not managing the server.

### Why to use Spring DevTools?

  • Automatic Restart -> Automatically restart the app when you change a class or file like home.html file.
  • Live Reload -> Automatically refresh the browser when templates(html/Thymeleaf)change.
  • Catching Disabled -> Disable template or static file catching during development.
  • No need to Re-run -> you do not need to stop/start/ the app manually every time.

Step:3
create QuoteService class then add top of class @Service ,ctr+shift+o(import service)

step:4
create method:

public String show_quote()
    {
    //List<String> quoteList = new ArrayList<String>
    List<String> quoteList = List.of("Try Hard","Hard work never fails","Spend Time wisely","Practice brings Perfection");

    Random random = new Random();
    int random_no =random.nextInt(quoteList.size()); 
    return quoteList.get(random_no);
    }
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Why not used now this line
List<String> quoteList = new ArrayList<String>

  • Creates a modifiable(not-fixed) list
  • you can add, remove,update values.
  • Used when list changes at runtime

why used this line
List<String> quoteList = List.of(....);

  • creates an unmodified(fixed) list
  • you can not modify(add/remove) values.
  • used when list constant/randomly changed

Step:5 Random is a class in Java (java.util.Random)

  • it is used to generate the random numbers.Can be used to get: Random int,double,Boolean...etc. nextInt is generate random number from 0 to n-1 , when use quoteList.size() ,it give random valid index list like now we have 3 list quoteList, random number from 0 to 2 , because random starts 0 
Random random = new Random();
    int num =random.nextInt(quoteList.size());
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Step:6

  • create controller class QuotesController and we use dependence injection , one of type for field(auto-wiring with @Autowired) not to create object,if you create object it lead to tightly couple.

  • @GetMapping is used in a controller to handle HTTP GET requests.Model is an interface used in controller classes to store and pass objects (like List, String, .. etc)(data) to (Thymeleaf template)HTML view pages."

  • Thymeleaf is a template engine — it takes that Java data and dynamically renders(not fixed type value will change based on back end data or user input ) HTML content.

public class QuotesController {

    @Autowired
    private QuoteService quoteService;

    @GetMapping("/quotesPage")
    public String  display_Quotes(Model model)
    {
        String quote = quoteService.show_quote();
        model.addAttribute("Proverb", quote);
        return "quotes_page";

    }
}
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Step:7

Create quotes_page.html in /src/main/resource/template/

quotes_page.html

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org"> 

<head>
<title> Random Quote Generator

</title>  

<style>
div{
text-align: center;
}

</style>
<head>
<body>
<div>
<h2> Random Quote Generator</h2>
<h3 th:text="${proverb}"> </h3>
</div>
</body>
</html>
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class QuoteService

import org.springframework.stereotype.Service;

@Service
public class QuoteService {
    public String show_quote()
    {
    //List<String> quoteList = new ArrayList<String>
    List<String> quoteList = List.of("Try Hard","Hard work never fails","Spend Time wisely","Practice brings Perfection");

    Random random = new Random();
    int random_no =random.nextInt(quoteList.size()); 
    return quoteList.get(random_no);
    }


}
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// List is interface ,Hold multiple values like array ,follow insertion order(first added item stays first, second stays second),allowed duplicate values,you can access element by index.

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