Example: Formatting Output

/*
 * FormatMe.java
 *
 * Created on January 14, 2002, 12:30 AM
 */

// Import the NumberFormat class so that we can use it below.
import java.text.NumberFormat;

// Import the swing package so that we can prompt the user.
import javax.swing.JOptionPane;

/**
 * FormatMe
 *
 * Show use of formatting output.
 *
 * @author  jonesbr@email.uc.edu
 */
public class FormatMe {

    /** Creates a new instance of FormatMe */
    public FormatMe() {
    }
 
    public void promptUser() {
        // Wrap in a try-catch block.
        try {
            // Prompt the user for a number.
            String strNumber = JOptionPane.showInputDialog("Give me a number.");

            // Convert the string input to a double by using the static parseDouble()
            // method of the Double class.
            double dblNumber = Double.parseDouble(strNumber);

            // Create some NumberFormat instances.
            NumberFormat altNumber = NumberFormat.getNumberInstance();
            altNumber.setMaximumFractionDigits(5);
            altNumber.setMinimumFractionDigits(3);
            NumberFormat normalNumber = NumberFormat.getNumberInstance();
            NumberFormat currency = NumberFormat.getCurrencyInstance();
            NumberFormat percent = NumberFormat.getPercentInstance();
 
            // Print the results to standard output.
            System.out.println("Number with fraction digits range 3-5: " + altNumber.format(dblNumber));
            System.out.println("Number with no restrictions: " + normalNumber.format(dblNumber));
            System.out.println("Number as currency: " + currency.format(dblNumber));
            System.out.println("Number as percentage: " + percent.format(dblNumber));
 
        // Catch number format error, try again.
        } catch (NumberFormatException e) {
            System.out.println("Idiot.  I said enter a number.  Try again.");
            promptUser();
        }
    }
 
    /**
     * Instantiates new FormatMe from user input.
     *
     */
 
    public static void main(String args[]) {
        FormatMe formatMe = new FormatMe();
        formatMe.promptUser();
    }
 
 
}

• When we enter 5.101059, we get:

• Note that the truncation automatically rounded the decimal.
• If we had entered text, it would prompt us to enter a number.

Created by:  Brandan Jones January 4, 2002