FileWritter write integers as illegal characters

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.