java - 根据输入将文本输入转换为 int 或 double

Question

我有一个 JFrame，我从文本字段中获取输入并将其转换为整数。如果它是双精度数，我还想将它转换为双精度数，如果它既不是整数也不是双精度数，我可能会返回一条消息。我怎样才能做到这一点？

我当前的代码：

 int textToInt = Integer.parseInt(textField[0].getText());

Answer 1

String text = textField[0].getText();
try {
    int textToInt = Integer.parseInt(text);
    ...
} catch (NumberFormatException e) {
    try {
        double textToDouble = Double.parseDouble(text);
        ...
    } catch (NumberFormatException e2) {
        // message?
    }
}

为了保持精度，立即解析为 BigDecimal。这个 parseDouble 当然不是特定于语言环境的。

Answer 2

try {
    int textToInt = Integer.parseInt(textField[0].getText());
} catch(NumberFormatException e) {
    try {
        double textToDouble = Double.parseDouble(textField[0].getText());
    } catch(NumberFormatException e2) {
        System.out.println("This isn't an int or a double";
    }
}

Answer 3

boolean isInt = false;
boolean isDouble = false;
int textToInt = -1;
double textToDouble = 0.0;

try {
    textToInt = Integer.parseInt(textField[0].getText());
    isInt = true;
} catch(NumberFormatException e){
    // nothing to do here
}

if(!isInt){
    try {
        textToDouble = Double.parseDouble(textField[0].getText());
        isDouble = true;
    } catch(NumberFormatException e){
        // nothing to do here
    }
}

if(isInt){
 // use the textToInt
}

if(isDouble){
 // use the textToDouble
}
if(!isInt && !isDouble){
// you throw an error maybe ?
}

Answer 4

检查字符串是否包含小数点。

if(textField[0].getText().contains(".")) 
    // convert to double 
else 
    // convert to integer 

不需要抛出异常。

在执行上述操作之前，您可以使用正则表达式检查字符串是否为数字。一种方法是使用模式[0-9]+(\.[0-9]){0,1}。我不是最好的正则表达式，所以如果这是错误的，请纠正我。

Answer 5

您可以尝试一系列嵌套的 try-catch：

String input = textField[0].getText();
try {
    int textToInt = Integer.parseInt(input);
    // if execution reaches this line, it's an int
} catch (NumberFormatException ignore) {
    try {
        double textToDouble = Double.parseDouble(input);
        // if execution reaches this line, it's a double
    } catch (NumberFormatException e) {
        // if execution reaches this line, it's neither int nor double
    }
}