如何解析比NumberFormat在Java中更严格的数字？

问题描述

我正在验证表单中的用户输入。

I'm validating user input from a form.

我用，但它很邪恶，几乎可以允许任何内容。有没有办法解析数字更严格？

I parse the input with NumberFormat, but it is evil and allow almost anything. Is there any way to parse number more strict?

例如。我想不允许这三个输入，对于一个整数，但 Numberformat 允许所有这些：

E.g. I would like to not allow these three inputs, for an integer, but Numberformat allow all of them:

NumberFormat nf = NumberFormat.getNumberInstance();
nf.setParseIntegerOnly(true);

Number numberA = nf.parse("99.731");    // 99 (not what the user expect)
Number numberB = nf.parse("99s.231");   // 99 (invalid)
Number numberC = nf.parse("9g9");       // 9  (invalid)

System.out.println(numberA.toString());
System.out.println(numberB.toString());
System.out.println(numberC.toString());

推荐答案

也许这会有所帮助：

String value = "number_to_be_parsed".trim();
NumberFormat formatter = NumberFormat.getNumberInstance();
ParsePosition pos = new ParsePosition(0);
Number parsed = formatter.parse(value, pos);
if (pos.getIndex() != value.length() || pos.getErrorIndex() != -1) {
    throw new RuntimeException("my error description");
}

（感谢）

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