Ejemplos Java

Hola mundo

En python:

print "Hello World!"

En java:

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

Ejemplo de lectura con Scanner

import java.util.Scanner;
 
public class TempConv {
    public static void main(String[] args) {
        Double fahr;
        Double cel;
        Scanner in;
 
        in = new Scanner(System.in);
        System.out.println("Enter the temperature in F: ");
        fahr = in.nextDouble();
 
        cel = (fahr - 32) * 5.0/9.0;
        System.out.println("The temperature in C is: " + cel);
 
        System.exit(0);
    }
}

Ejemplo con swing

import javax.swing.*;
 
public class TempConvGUI {
 
    public static void main(String[] args) {
        String fahrString;
        Double fahr, cel;
 
        fahrString = JOptionPane.showInputDialog("Enter the temperature in F");
        fahr = new Double(fahrString);
        cel = (fahr - 32) * 5.0/9.0;
 
        JOptionPane.showMessageDialog(null,"The temperature in C is, " + cel);
    }
}