.

Contador com Spring Boot

import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import java.util.Scanner;

@SpringBootApplication
public class ContadorApplication implements CommandLineRunner {
    public static void main(String[] args) {
        SpringApplication.run(ContadorApplication.class, args);
    }

    @Override
    public void run(String... args) {
        System.out.print("Digite um número: ");
        int n = new Scanner(System.in).nextInt();
        for (int i = 1; i <= n; i++) System.out.print(i + " ");
    }
}

Serialização/Desserialização com Spring Boot

import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import com.fasterxml.jackson.databind.ObjectMapper;

@SpringBootApplication
public class App implements CommandLineRunner {
    public static void main(String[] args) {
        SpringApplication.run(App.class, args);
    }

    @Override
    public void run(String... args) throws Exception {
        ObjectMapper mapper = new ObjectMapper();
        
        // Serialização
        Tarefa t = new Tarefa("Estudar Spring Boot", false, "Dev");
        mapper.writeValue(new java.io.File("tarefa.json"), t);
        System.out.println("Tarefa salva!");
        
        // Desserialização
        Tarefa t2 = mapper.readValue(new java.io.File("tarefa.json"), Tarefa.class);
        System.out.println("Tarefa lida: " + t2);
    }
}

class Tarefa {
    public String descricao;
    public boolean concluida;
    public String pessoaResponsavel;
    
    public Tarefa() {}
    
    public Tarefa(String d, boolean c, String p) {
        this.descricao = d;
        this.concluida = c;
        this.pessoaResponsavel = p;
    }
    
    @Override
    public String toString() {
        return descricao + " (" + pessoaResponsavel + ") - " + (concluida ? "OK" : "Pendente");
    }
}