java - Double.parseDouble 和 Integer.parseInt 之间的行为差​​异

Question

似乎 parseDouble 可以接受带有尾随空格的字符串，但 parseInt 和 parseLong 会抛出异常。

例如对于这个测试用例

@Test
public void testNumberParsing() {
    try {
        Double.parseDouble("123.0 ");
        System.out.println("works");
    }catch (NumberFormatException e) {
        System.out.println("does not work");
    }
    try {
        Integer.parseInt("123 ");
        System.out.println("works");
    }catch (NumberFormatException e) {
        System.out.println("does not work");
    }
    try {
        Long.parseLong("123 ");
        System.out.println("works");
    }catch (NumberFormatException e) {
        System.out.println("does not work");
    }
}

结果是

works
does not work
does not work

为什么会有不同的行为？这是故意的吗？

Answer 1

这种行为实际上已被记录(尽管这是一个非常糟糕的设计......)!

Double.parseDouble :

Returns a new double initialized to the value represented by the specified String, as performed by the valueOf method of class Double.

Double.valueOf :

Leading and trailing whitespace characters in s are ignored. Whitespace is removed as if by the String.trim() method; that is, both ASCII space and control characters are removed.

Integer.parseInt :

The characters in the string must all be decimal digits, except that the first character may be an ASCII minus sign '-' ('\u002D') to indicate a negative value or an ASCII plus sign '+' ('\u002B') to indicate a positive value.