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November 16th, 2011, 01:16 AM
#1
Calculate Distance Traveled (using Methods)
Hey guys - I need some help...
I'm trying to create a program that calculates Distance Traveled using user-input for their Speed and Time. However, the assignment requires that I write a separate method for the computation of the Distance and another to DisplayData, so I can recall it back in the Main method, then display the results in another method. But - I keep getting some errors. Any help will surely be appreciated. Thanks in advance.
Here's the Errors I'm getting from the compiler:
DistTravel.java:25: error: variable speed might not have been initialized
displayData(speed, time);
^
DistTravel.java:25: error: variable time might not have been initialized
displayData(speed, time);
^
2 errors
P.S. Bare with me on my coding. I am an amateur at Java Programming. Still learning.
Code:
import javax.swing.JOptionPane;
import java.io.*;
public class DistTravel
{
public static void main(String[] args) throws IOException
{
// Declare the variables.
String input;
int speed, time;
// The 'Distance Traveled' equation.
Distance();
// Display Data
displayData(speed, time);
System.exit(0);
}
public static int Distance()
{
// Get the vehicle speed from the user.
// Declare the variables
int speed;
int time;
String input; // To hold user's input.
input = JOptionPane.showInputDialog("What is your vehicle's speed in miles-per-hours? ");
// Convert the input to a double.
speed = Integer.parseInt(input);
while (speed <= 0)
{
input = JOptionPane.showInputDialog("Your speed must be greater than zero. Please re-enter. ");
speed = Integer.parseInt(input);
}
// Get the hours traveled from the user.
input = JOptionPane.showInputDialog("How many hours have you traveled, thus far? ");
time = Integer.parseInt(input);
while (time <= 1)
{
input = JOptionPane.showInputDialog("How many hours have you traveled for? ");
time = Integer.parseInt(input);
}
return speed * time;
}
public static void displayData(int speed, int time)
{
for(int i = 1; i <= time; i++)
{
JOptionPane.showMessageDialog(null, "Hour(s): Distance Traveled" +
"----------------------------" + "Hour" + ": " + i + (speed * i) + " miles traveled");
}
}
}
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November 17th, 2011, 08:37 AM
#2
Re: Calculate Distance Traveled (using Methods)
The error messages tell you what is wrong ie:
variable speed might not have been initialized: means the variable called 'speed' is being used before you have definitely assigned a value to it - remember class and instance variable are given default values when they are declared but local variables are not.
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