FileWritter 将整数写入为非法字符

Question

i'm currently writting an algorithm who write another algorithm. For this i'm using the FileWritter class and this worked fine until i tried to write integers in the file.

fileWriter.write(1); print `` (edit: you can't see the character in here) that intelliJ interpret as: Illegal Character U+0001 (every number has a different name of illegal character)

When i'm doing fileWriter.write("1") this work fine.

Does the problem come from Intellij or do i have to convert every integers to String?

Answer 1

Basically Writer.write(int) doesn't do what you expect it to. The documentation says:

Writes a single character. The character to be written is contained in the 16 low-order bits of the given integer value; the 16 high-order bits are ignored.

So you're writing U+0001, just as IntelliJ is saying.

It's not the greatest API in the world (it would be better to accept char for a single character) but it is behaving as designed.

Basically, yes, you need to convert everything to text.

Answer 2

The FileWriter.write(int) method, which is inherited from OutputStreamWriter.write(int) , writes a single character to a file. The input int is the ASCII or Unicode representation of the character. For instance, writing fileWriter.write(65) writes the letter A , as A 's ASCII value is 65. This could also be written as fileWriter.write('A') , as the character A is represented in memory as the number 65 . If you want to write an integer to a file, you will need to call fileWriter.write(Integer.toString(i)) , where i is the value you want to write. Alternatively, if i is a single-digit positive number, you can write fileWriter.write('0' + i) , as adding '0' to such a digit converts it into its corresponding character.