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STRINGS AND NUMBERS

Posted on 1998-07-06
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Last Modified: 2010-03-30
I am producing a simple Applet where the user enters a number into a text field and the computer performs some basic mathematics on the number entered. The problem is that the only commands that I can find for getting ands setting the field are 'getText' and 'setText'. These two commands only work on strimng value and I cannot find any Java commands for switching between strings and numbers.

Any help would be much appreiated.

Richard H
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Question by:RICHARDH
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gadio earned 30 total points
ID: 1224713
RICHARDH, what you need is to use the formatters that java provides. The formatters are part of the java.text package. Here is an samll example of how to use diferent types of them:
---------
    //.....
    //Formatters to format and parse numbers
    private NumberFormat moneyFormatter;
    private NumberFormat percentFormatter;
    private NumberFormat integerFormatter;
    private DateFormat dateFormatter;

    //.....
    //.....
    private void setUpFormatters() {
        dateFormatter = new SimpleDateFormat("dd/MM/yy HH:mm");

        moneyFormatter = NumberFormat.getCurrencyInstance(Locale.US);

        percentFormatter = NumberFormat.getPercentInstance(Locale.US);
        percentFormatter.setMinimumFractionDigits(3);

        integerFormatter = NumberFormat.getNumberInstance(Locale.US);
        integerFormatter.setParseIntegerOnly(true);
    }
    //.....
    //.....
    //.....
   
        // using a formatter inside some function:
        // theformatter is one of the formatters instances defined above.
        public void actionPerformed(ActionEvent evt) {

            JTextField inputField = (JTextField)evt.getSource();

            try {
                if( theformatter instanceof NumberFormat ) {
                    NumberFormat formatter = (NumberFormat)theformatter;
                    Number value = formatter.parse(inputField.getText());
                    if (inputField == amountField)
                        amount = value.doubleValue();
                    else if (inputField == rateField)
                        rate = value.doubleValue();
                    else if (inputField == numPeriodsField)
                        numPeriods = value.intValue();
   
                    //Recalculate
                    payment = computePayment(amount, rate, numPeriods);

                    // Display
                    paymentField.setText(moneyFormatter.format(payment));
                }
                else {
                    DateFormat formatter = (DateFormat)theformatter;
                    Date value = formatter.parse(inputField.getText());

                    // Display
                    paymentField.setText(dateFormatter.format(value));
                }
            } catch (ParseException e) {
                Toolkit.getDefaultToolkit().beep();
                paymentField.setText("Input Error");
            }
        }
    }
-----------------------------
Hope that will help you.
G.
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