Java gui 空白空间错误检查

Question

在

我试图为类分配完成的 Java swing gui 上进行了一些错误检查。需要检查的部分是用户在计算之前输入比萨饼数量和苏打水数量的数字。我希望程序做的是检测一个空格并提供一个弹出窗口，告诉用户该空格是空白的，并且需要 0-100 之间的数字。我正在寻找它来做任何事情，除了崩溃或给出例外。一旦我们弄清楚错误检查，我会担心弹出窗口的文本。非常感谢任何和所有的帮助。

private void btnCalcActionPerformed(java.awt.event.ActionEvent evt) {                                        
    final double LOCAL_TAX = .02;
    final double STATE_TAX = .06;
    NumberFormat nf = NumberFormat.getCurrencyInstance();
    int intPizza = Integer.parseInt(qtyInputPizza.getText());
        while (!intPizza.hasNextInt(101))
            {
            }
    int intSoda = Integer.parseInt(qtyInputSoda.getText());
    double dblPizzaSub = intPizza * PIZZA_PRICE;
    double dblSodaSub = intSoda * SODA_PRICE;
    pizzaSubtotal.setText(nf.format(dblPizzaSub));
    sodaSubtotal.setText(nf.format(dblSodaSub));
    double dblNetSale = dblPizzaSub + dblSodaSub;
    netSaleValue.setText(nf.format(dblNetSale));
    double dblStateTax = dblNetSale * STATE_TAX;
    double dblLocalTax = dblNetSale * LOCAL_TAX;
    stateTaxValue.setText(nf.format(dblStateTax));
    localTaxValue.setText(nf.format(dblLocalTax));
    double dblTotalSale = dblNetSale + dblStateTax + dblLocalTax;
    totalSaleValue.setText(nf.format(dblTotalSale));
    btnClear.requestFocusInWindow();
}

Answer 1

替换此行：

int intPizza = Integer.parseInt(qtyInputPizza.getText());

由

String strPizza = qtyInputPizza.getText();
int intPizza = 0;
if ( strPizza == null || strPizza.trim().length() == 0 ) {
  // Display your error message
}
else
{
 // You can add a test to make sure it is an int not something else
 ntPizza = Integer.parseInt( strPizza  );
}