Can an integer always be parsed as a long?

Question

I have a list of strings in Java which are being written to a text file. These strings are each tagged with a type -- in this case, I'll I'm interested are strings containing long s and int s. I'd like to convert these strings back to a numeric type before writing them, but I'd like to minimize code duplication. I plan on parsing every string tagged as an integer or long integer using Long.parseLong() .

My question is this: are there any situations in which a valid integer will not parse as a long? I can't think of any (with the exception of maybe "1000L" or some such), but my experience in these matters has taught me that there are often nuances that I miss.

Answer 1

Yes, integers can always be cast into long, but long cant always be cast into int.

An int is really a 4-byte whole number and a long is 8 bytes. So a long gives you 4 more bytes from an int.

Answer 2

Long.parseLong("1000L") results in a NumberFormatException -- it accepts string-encoded numeric values, not necessarily Java number literals (although there is a large overlap).

Because of this Long.parseLong encompasses Integer.parseInt entirely just as the values of int are a proper subset of the values of long .

Happy coding.

Answer 3

这应该没问题，因为整数是多头的子集。

Answer 4

checking the description of the both methods

the answer is no (except when l or L appears after the string)

Answer 5

每个可能的int值都可以存储在long或double （或BigInteger）中