Java basico

import java.util.ArrayList;

import java.util.LinkedList;

import java.util.List;

import java.util.Vector;

public class Main

{

public static void main(String[] args) {

System.out.println("Simulacion correo electronico \n");

List<Correo> lList = new LinkedList<Correo>();

lList.add(new Correo("Carlos Daniel", "aguila--carlos@hotmail.com"));

lList.add(new Correo("Alondra","viguerasalondra9@gmail.com"));

lList.add(new Correo("Juan","juanito@gmail.com"));

lList.add(new Correo("Araceli","vara9@gmail.com"));

lList.add(new Correo("Abril","abeja@gmail.com"));

lList.add(new Correo("Dulcedeleche","dulce@gmail.com"));

lList.add(new Correo("Omar","omarcito@gmail.com"));

lList.add(new Correo("Ximena","xiximea12@gmail.com"));

lList.add(new Correo("Rey","reylo@gmail.com"));

lList.add(new Correo("Obiwan","BennKenobi@gmail.com"));

lList.add(new Correo("Luke","Asesino68@gmail.com"));

lList.add(new Correo("Leia","Voladora21@gmail.com"));

lList.add(new Correo("David","davichupidupi@gmail.com"));

lList.add(new Correo("Lalo","lalocomotora@gmail.com"));

lList.add(new Correo("Maria","Chuy4321@gmail.com"));

lList.add(new Correo("Mireya","mire_fsba12@gmail.com"));

lList.add(new Correo("Paula","Alexis_21pau@gmail.com"));

lList.add(new Correo("Romina","Gurrumina65@gmail.com"));

lList.add(new Correo("Tete","Villa_mama@gmail.com"));

lList.add(new Correo("Carlos","chop21@gmail.com"));

//System.out.println(str.contains("h"));

for(Correo c : lList ){

System.out.println("Correo enviado a: "+c.email + " -> " + c.name );

}

}

}

class Correo {

String name;

String email;

Correo(String name , String email){

this.name = name;

this.email = email;

}

}

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Programa pract 1

Leer un numero y mostrar su cuadrado... No aceptar num negativos

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import java.util.Scanner;

public class Main

{

public static void main(String[] args) {

//Declaracion variables

boolean x = true;

int num;

//Inicio del Ciclo Do-While

do{

Scanner sc = new Scanner(System.in); //SCANNER

//Solicitar un numero

System.out.println("Ingresa un numero que sea positivo");

num = sc.nextInt();

//Es positivo?

if (num > 0){

System.out.println("El numero ingresado es: "+ num);

//Operacion del cuadrado

int y = num* num;

System.out.println("\n Su numero al cuadrado es "+ y);

}

//Es negativo? cierra

...