could please help to write a program using loop (if-else)

I don't experience in programing could please help me
Write a program that will have a following menu
1.Convert fahrenheit to Celsius
2. Convert Celsius to Fahrenheit
The formula for conversion is:

fahrenheit=(9.0)/5)*celsius + 32
Celsius=(5/9)(f-32)
import javax.swing.JOptionPane;
publicclass temperatura
{
publicstaticvoid main (String[]args)
{
int temp;
finalfloat fahrenheit,celsius;


System.out.println("enter temperature celsius");

String input=JOptionPane.showinputDialog(null,"Enter your temperature in celsius", "fahrenheit",JOptionPane.QUESTION_MESSAGE);
floatfahrenheit=parsefloat(input);

if (temp == fahrenheit)
{
fahrenheit=(9.0/5)*temp+32;
System.out.println("temperature in celsius");

JOptionPane.showinputDialog(null,"Enter your temperature in celsius", + celsius, "Output ",JOptionPane_INFORMATION_MESSAGE);
}
else (temp == celsius)
{
celsius=(5/9)*(temp -32);
System.out.println("temperature in fahrenheit");
}

JOptionPane.showinputDialog(null,"Enter your temperature in celsius", + celsius, "Output ",JOptionPane.INFORMATION_MESSAGE);


}
}

Ooops, I replied to the wrong person..... My Bad......Anyways.... Here's What I tried out today, maybe it will help you...... :

package Temperatura;
import javax.swing.JOptionPane;
public class temperatura
{
public static void main (String[] args)
{
String celsius; // first string entered by user
String fahrenheit; // second string entered by user
String temp; // third string by user
int t; // else if variable
double f; // fahrenheit variable used for both RESULT and celsius calculation
double c; // celsius variable used for both RESULT and fahrenheit calculation
celsius = JOptionPane.showInputDialog( "Enter the temperature in celsius: ");
fahrenheit = JOptionPane.showInputDialog("Enter the temperature in fahrenheit: ");
c = Double.parseDouble(celsius);
f = Double.parseDouble(fahrenheit);

//attempt a menu to calculate either celsius or fahrenheit
temp = JOptionPane.showInputDialog("Enter which temp to calculate 1. celsius or 2. fahrenheit ");

// check menu number for correct t value
t = Integer.parseInt(temp);
JOptionPane.showMessageDialog(null, "You entered: " + t, "RESULTS", JOptionPane.PLAIN_MESSAGE);
if (t == 1) //calculate fahrenheit
{
f =(9.0/5)*c + 32;

// display result
JOptionPane.showMessageDialog(null, "The temperature in fahrenheit is: " + f, "RESULTS", JOptionPane.PLAIN_MESSAGE);
}
else if (t == 2) // calculate celsius
{
c = ((5.0/9) * (f - 32));

JOptionPane.showMessageDialog(null, "The temperature in celsius is: " + c, "RESULTS", JOptionPane.PLAIN_MESSAGE);
}
JOptionPane.showMessageDialog(null, "That's all Folks\nOK I had fun learning this also,\nI'm addicted... I admit it....lol!!!"); // enter silly message here
System.exit(0);
}// end main
}// end class temperatura

Try using [code][/code] tags when posting your code to the forum.
These tags are designed to keep your indents and code structure.