[英]Having trouble with JOPtionPane
我是Java的初学者,遇到一些困难。 我正在使用JOPtionPane询问用户一些问题。 但是,我的困难来自于这样一个事实:当用户单击X或取消程序中的任何位置时,我不知道如何正确处理异常。 另外,当我查看Java API并了解如何实现标题时,我尝试了一下,但是现在应该在文本字段中放置标题。
从程序的其他部分退出也会在主线程中产生异常,因此我希望能够捕获这些异常并正常退出而不是出错。 同样,在输入对话框中,标题“ Investment Advisor”将显示在文本字段内。 我看过API,看来我使用的是正确的格式,但显然没有。 具有输入对话框的图标也是如此。 我不希望它们显示,但是程序无法编译,并且说如果我将它们放在输入对话框中也找不到符号。 它适用于optiondialog。
以上是解决问题之前的问题
非常感谢那些花时间阅读本文的人。
这是代码(请注意investment1和investment2只是具有适当公式的简单静态方法):
编辑下面的代码; 只需尝试为空字符串添加错误检查
public static void main(String[] args)
{
String initialAmt_Str, targetAmt_Str, interestPct_Str, years_Str, result;
double principle = 0, target = 0, interest = 0;
int again = JOptionPane.NO_OPTION, time = 0;
NumberFormat fmt = NumberFormat.getCurrencyInstance();
do {
Object[] options = {"Compute years to reach target amount",
"Compute target amount given number of years"};
int choice = JOptionPane.showOptionDialog(null, "Please choose what you would like to do.",
"Investment Advisor", JOptionPane.YES_NO_OPTION,
JOptionPane.PLAIN_MESSAGE, null, options, null);
if (choice != JOptionPane.CANCEL_OPTION)
{
if (choice == 1)
{
initialAmt_Str = JOptionPane.showInputDialog (null, "Enter the principle:", "Investment Advisor",
JOptionPane.PLAIN_MESSAGE);
if (initialAmt_Str != null)
principle = Double.parseDouble(initialAmt_Str);
else
System.exit(0);
interestPct_Str = JOptionPane.showInputDialog (null, "Enter the interest rate as a"
+ " percentage (without the percent sign):", "Investment Advisor", JOptionPane.PLAIN_MESSAGE);
if (interestPct_Str != null)
interest = Double.parseDouble(interestPct_Str);
else
System.exit(0);
years_Str = JOptionPane.showInputDialog (null, "Enter the amount of years:", "Investment Advisor",
JOptionPane.PLAIN_MESSAGE);
if (years_Str != null)
time = Integer.parseInt(years_Str);
else
System.exit(0);
result = "Your target amount given the number of years is " +
fmt.format(investment2(principle, interest, time)) + ".";
JOptionPane.showMessageDialog (null, result, "Investment Advisor", JOptionPane.PLAIN_MESSAGE);
again = JOptionPane.YES_OPTION;
}
}
else
again = JOptionPane.NO_OPTION;
if (choice == 0)
{
initialAmt_Str = JOptionPane.showInputDialog (null,"Enter the principle:","Investment Advisor",
JOptionPane.PLAIN_MESSAGE);
if (initialAmt_Str != null)
principle = Double.parseDouble(initialAmt_Str);
else
System.exit(0);
interestPct_Str = JOptionPane.showInputDialog (null, "Enter the interest rate as a"
+ " percentage (without the percent sign):", "Investment Advisor", JOptionPane.PLAIN_MESSAGE);
if (interestPct_Str != null)
interest = Double.parseDouble(interestPct_Str);
else
System.exit(0);
targetAmt_Str = JOptionPane.showInputDialog (null, "Enter your target amount:", "Investment Advisor",
JOptionPane.PLAIN_MESSAGE);
if (targetAmt_Str != null)
target = Double.parseDouble(targetAmt_Str);
else
System.exit(0);
result = "You will reach your target amount in " +
investment1(principle, target, interest) +
(investment1(principle, target, interest) == 1 ? " year." : " years.");
JOptionPane.showMessageDialog (null, result, "Investment Advisor", JOptionPane.PLAIN_MESSAGE);
again = JOptionPane.YES_OPTION;
}
if (again != JOptionPane.NO_OPTION)
again = JOptionPane.showConfirmDialog(null, "Find Another?", "", JOptionPane.YES_NO_OPTION,
JOptionPane.PLAIN_MESSAGE);
} while (again == JOptionPane.YES_OPTION);
}
如果用户单击“ x”关闭按钮,则JOptionPane
将返回JOptionPane.CLOSED_OPTION
您应该先检查一下...
if (choice != JOptionPane.CLOSED_OPTION) {
// Do the normal stuff
} else {
// Break out of the do loop
break;
}
您还应该注意,使用JOptionPane.showOptionDialog
, JOptionPane
将返回用户选择的选项的索引。
这意味着返回值0
表示用户选择"Compute years to reach target"
,返回值1
表示用户选择"Compute target given number of years"
使用JOptionPane.NO_OPTION
或JOptionPane.YES_OPTION
可能无法获得预期的结果...
更新了示例
您的重组允许一个稍微“偷偷摸摸”的选项,而不是使用break,当用户关闭选项对话框时,我简单地将again
变量设置为JOptionPane.NO_OPTION
。
public static void main(String[] args) {
String initialAmt_Str, targetAmt_Str, interestPct_Str, years_Str, result;
double principle, target, interest;
int again, time;
NumberFormat fmt = NumberFormat.getCurrencyInstance();
do {
Object[] options = {"Compute years to reach target",
"Compute target given number of years"};
int choice = JOptionPane.showOptionDialog(null, "Please choose what you would like to do.",
"Investment Advisor", JOptionPane.YES_NO_OPTION,
JOptionPane.PLAIN_MESSAGE, null, options, null);
if (choice != JOptionPane.CANCEL_OPTION) {
if (choice == 1) {
JOptionPane.showMessageDialog(null, "Compute target given number of years");
} else if (choice == 0) {
JOptionPane.showMessageDialog(null, "Compute years to reach target");
}
again = JOptionPane.showConfirmDialog(null, "Find Another?");
} else {
again = JOptionPane.NO_OPTION;
}
} while (again == JOptionPane.YES_OPTION);
}
更新了其他示例以处理取消的输入
因此,如果用户在输入对话框中单击“ x”按钮,则他们将返回null
。 此时,您需要检查是否为null
结果,然后选择要如何处理它。 在下面的示例中,我只是将again
设置为等于JOptionPane.NO_OPTION
public static void main(String[] args) {
String initialAmt_Str, targetAmt_Str, interestPct_Str, years_Str, result;
double principle, target, interest;
int again, time;
NumberFormat fmt = NumberFormat.getCurrencyInstance();
do {
Object[] options = {"Compute years to reach target",
"Compute target given number of years"};
int choice = JOptionPane.showOptionDialog(null, "Please choose what you would like to do.",
"Investment Advisor", JOptionPane.YES_NO_OPTION,
JOptionPane.PLAIN_MESSAGE, null, options, null);
if (choice != JOptionPane.CANCEL_OPTION) {
again = JOptionPane.YES_OPTION;
if (choice == 1) {
String input = JOptionPane.showInputDialog("Enter the principle:", "Investment Advisor");
if (input != null) {
// Process further...
System.out.println("Continue processing...");
} else {
again = JOptionPane.NO_OPTION;
}
} else if (choice == 0) {
String input = JOptionPane.showInputDialog("Enter your target amount:", "Investment Advisor");
if (input != null) {
// Process further...
System.out.println("Continue processing...");
} else {
again = JOptionPane.NO_OPTION;
}
}
if (again != JOptionPane.NO_OPTION) {
again = JOptionPane.showConfirmDialog(null, "Find Another?");
}
} else {
again = JOptionPane.NO_OPTION;
}
} while (again == JOptionPane.YES_OPTION);
}
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.