import java.util.Scanner;
public class Aula{
String numeroAula = "01";
void ejecutar(){ // metodo de la clase aula que nos permite crear personas dentro de la clase
String d = "";
Persona persona; // una declaracion de persona, no se ha creado, solo declarado
Scanner input = new Scanner(System.in);
int maximoDePersonasAIngresar = 10; // el maximo de personas que vamos a permitir ingresar
Persona [] vectorPersona = new Persona[maximoDePersonasAIngresar]; // el vector con el tamano maximo de personas a ingresar
int i = 0;
int t = 0;
String g = "";
/*
/ El valor && que pueden ver es un AND es decir,
/ que se ejecutara lo que esta dentro del while si ambas condiciones son verdaderas
/ Lo que es lo mismo, si d es distinto de "si" y si i es menor a al maximo de personas a ingresar
*/
while(!d.equals("si") && i < maximoDePersonasAIngresar){
System.out.println("Digite el nombre");
g = input.next(); // ingresamos en el sistema el nombre del usuario
persona = new Persona(g, 15, "0000"+t, 1.2f);
vectorPersona[i++] = persona;
System.out.println(persona.getCedula()+" "+persona.getNombre());
t++;
System.out.println("Desea detenerse?");
d = input.next(); // si escribimos si, el programa se detiene, sino no
}
if(i == maximoDePersonasAIngresar){ // advertencia del maximo de personas alcanzado
System.out.println("El numero maximo de personas a ingresar se ha alcanzado");
}
for(int j = 0; j < i; j++){ // impresion de personas. Se pone i como la condicion de parada por que nos dice la cantidad de personas ingresada, es decir, pudieron ser menos del maximo, asi no improme basura
System.out.println(vectorPersona[j].getNombre()+" "+vectorPersona[j].getCedula());
vectorPersona[j].dormir(j+3); // Llamo al metodo de dormir de cada persona
}
}
private static class Persona{ // Creamos el modelo de una persona (su clase)
// los atributos y metodos static son valores que comparten todas las personas, es generico
static int ojos = 2;
static boolean piel = true;
static String humanidad = "si";
// estos son los atributos que hacen a una persona unica
String nombre = "";
String cedula = "";
float estatura = 0.0f;
int edad = 0;
boolean habla = true;
// Encapsulamiento, para poder acceder a los atributos de cada persona (solo son necesarios estos metodos si la clase es declarada private)
String getCedula(){
return cedula;
}
String getNombre(){
return nombre;
}
float getEstatura(){
return estatura;
}
int getEdad(){
return edad;
}
void setCedula(String cedula){
this.cedula = cedula;
}
void setNombre(String nombre){
this.nombre = nombre;
}
void setEstatura(float estatura){
this.estatura = estatura;
}
void setEdad(int edad){
this.edad = edad;
}
// Constructor de una persona, se crea una persona sin ningun tipo de informacion interna
Persona(){
}
// Constructor de una persona, se crea una persona con nombre y edad
Persona(String nombre, int edad){
this.nombre = nombre;
this.edad = edad;
}
// Constructor de una persona, se crea con nombre, edad, cedula y estatura
Persona(String nombre, int edad, String cedula, float estatura){
this.nombre = nombre;
this.edad = edad;
this.cedula = cedula;
this.estatura = estatura;
}
// metodo static, un metodo accesible aun si no se ha creado una persona
static void caminar(){
System.out.println("Camina");
}
// metodos de persona, accesibles desde la persona solo si ya esta creada
void dormir(int horas){
System.out.println("Esta persona de nombre "+this.nombre+" duerme "+horas+" horas");
}
// metodo que nos indica cuanto tiempo trabaja una persona
int trabajar(int x){
return x+2;
}
// un metodo que permite que la persona forme un platillo a partir de dos comidas
String come(String a, String b){
return "Platillo "+ a+" "+b;
}
}
public static void main(String [] args){
Aula aula = new Aula(); // Creamos un objeto de la clase Aula
System.out.println(aula.numeroAula); // Se puede accesar asi por que la clase es Aula se declaro public en la linea 2
aula.ejecutar(); // ejecutamos un metodo de la clase aula por que esta ya fue creada
}
} Write, Run & Share Java code online using OneCompiler's Java online compiler for free. It's one of the robust, feature-rich online compilers for Java language, running the Java LTS version 17. Getting started with the OneCompiler's Java editor is easy and fast. The editor shows sample boilerplate code when you choose language as Java and start coding.
OneCompiler's Java online editor supports stdin and users can give inputs to the programs using the STDIN textbox under the I/O tab. Using Scanner class in Java program, you can read the inputs. Following is a sample program that shows reading STDIN ( A string in this case ).
import java.util.Scanner;
class Input {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("Enter your name: ");
String inp = input.next();
System.out.println("Hello, " + inp);
}
}
OneCompiler supports Gradle for dependency management. Users can add dependencies in the build.gradle file and use them in their programs. When you add the dependencies for the first time, the first run might be a little slow as we download the dependencies, but the subsequent runs will be faster. Following sample Gradle configuration shows how to add dependencies
apply plugin:'application'
mainClassName = 'HelloWorld'
run { standardInput = System.in }
sourceSets { main { java { srcDir './' } } }
repositories {
jcenter()
}
dependencies {
// add dependencies here as below
implementation group: 'org.apache.commons', name: 'commons-lang3', version: '3.9'
}
Java is a very popular general-purpose programming language, it is class-based and object-oriented. Java was developed by James Gosling at Sun Microsystems ( later acquired by Oracle) the initial release of Java was in 1995. Java 17 is the latest long-term supported version (LTS). As of today, Java is the world's number one server programming language with a 12 million developer community, 5 million students studying worldwide and it's #1 choice for the cloud development.
short x = 999; // -32768 to 32767
int x = 99999; // -2147483648 to 2147483647
long x = 99999999999L; // -9223372036854775808 to 9223372036854775807
float x = 1.2;
double x = 99.99d;
byte x = 99; // -128 to 127
char x = 'A';
boolean x = true;
When ever you want to perform a set of operations based on a condition If-Else is used.
if(conditional-expression) {
// code
} else {
// code
}
Example:
int i = 10;
if(i % 2 == 0) {
System.out.println("i is even number");
} else {
System.out.println("i is odd number");
}
Switch is an alternative to If-Else-If ladder and to select one among many blocks of code.
switch(<conditional-expression>) {
case value1:
// code
break; // optional
case value2:
// code
break; // optional
...
default:
//code to be executed when all the above cases are not matched;
}
For loop is used to iterate a set of statements based on a condition. Usually for loop is preferred when number of iterations is known in advance.
for(Initialization; Condition; Increment/decrement){
//code
}
While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.
while(<condition>){
// code
}
Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.
do {
// code
} while (<condition>);
Class is the blueprint of an object, which is also referred as user-defined data type with variables and functions. Object is a basic unit in OOP, and is an instance of the class.
class keyword is required to create a class.
class Mobile {
public: // access specifier which specifies that accessibility of class members
string name; // string variable (attribute)
int price; // int variable (attribute)
};
Mobile m1 = new Mobile();
public class Greeting {
static void hello() {
System.out.println("Hello.. Happy learning!");
}
public static void main(String[] args) {
hello();
}
}
Collection is a group of objects which can be represented as a single unit. Collections are introduced to bring a unified common interface to all the objects.
Collection Framework was introduced since JDK 1.2 which is used to represent and manage Collections and it contains:
This framework also defines map interfaces and several classes in addition to Collections.
| Collection | Description |
|---|---|
| Set | Set is a collection of elements which can not contain duplicate values. Set is implemented in HashSets, LinkedHashSets, TreeSet etc |
| List | List is a ordered collection of elements which can have duplicates. Lists are classified into ArrayList, LinkedList, Vectors |
| Queue | FIFO approach, while instantiating Queue interface you can either choose LinkedList or PriorityQueue. |
| Deque | Deque(Double Ended Queue) is used to add or remove elements from both the ends of the Queue(both head and tail) |
| Map | Map contains key-values pairs which don't have any duplicates. Map is implemented in HashMap, TreeMap etc. |