I want to display an error message if the user does not enter a value so I used this. If you could help me to display my error when the user does not enter a value that would be great.
while (!choice.equalsIgnoreCase("y") && !choice.equalsIgnoreCase("n"))
{ //start of while
if (choice.isEmpty()) {
System.out.println("Error! This entry is required. Try again."); //display error message when the user enters invalid response
}
else {
System.out.println("Error! Entry must be 'y' or 'n'. Try again."); // display error message when the user enters no response
}
System.out.print ("Continue (y/n): "); //promt users for input
choice = sc.next();
} // End of while
The else part works but not the if. It just shows blank lines when I hit enter and I don't enter anything. Here is the full code for the whole program. It is a batting average app.
import java.util.*;
import java.text.NumberFormat;
public class BattingAverage
{
public static void main(String[] args)
{
System.out.println("Welcome to the Batting Average Calculator.");
System.out.println();
Scanner sc = new Scanner(System.in); // scanner for input
String choice = "y"; // initialize string
while (choice.equalsIgnoreCase("y")) //start of while to continue while the user answers y to the continue prompt below
{
int numberOfTimesAtBat;
System.out.print("Enter Number of times at bat: ");
numberOfTimesAtBat = sc.nextInt();
System.out.println("\n" + "0 = out, 1 = single, 2 = double, 3 = triple, 4 = home run");
int[] atBats = new int[numberOfTimesAtBat];
for(int counter = 0; counter < numberOfTimesAtBat; counter++){
System.out.print("Result for at-bat "+(counter+1)+": ");
atBats[counter] = sc.nextInt();
} //End of for
int sum = 0;
for (int i=0; i < atBats.length; i++) {
sum += atBats[i];
}
double Avg = sum / atBats.length;
// System.out.print("Batting average:" );
System.out.print("Slugging percent: " + Avg);
System.out.print ("\n" + "Continue (y/n): "); //promt users for input
choice = sc.next(); //make choice the next input
while (!choice.equalsIgnoreCase("y") && !choice.equalsIgnoreCase("n"))
{ //start of while
if (choice.isEmpty()) {
System.out.println("Error! This entry is required. Try again."); //display error message when the user enters invalid response
}
else {
System.out.println("Error! Entry must be 'y' or 'n'. Try again."); // display error message when the user enters no response
}
System.out.print ("Continue (y/n): "); //promt users for input
choice = sc.next();
} // End of while
} // end of while
} //end of main
} // end of class
You just have to change sc.next() to sc.nextLine() before the While loop,
choice = sc.nextLine(); //make choice the next input
while (!choice.equalsIgnoreCase("y") && !choice.equalsIgnoreCase("n"))
{ //start of while
if (choice.isEmpty()) {
System.out.println("Error! This entry is required. Try again."); //display error message when the user enters invalid response
}
else {
System.out.println("Error! Entry must be 'y' or 'n'. Try again."); // display error message when the user enters no response
}
System.out.print ("Continue (y/n): "); //promt users for input
choice = sc.next();
}