想请问为什么fileInputStream.read() != -1这样判断不行，必须用available()>0呢

Yes, we are discussing why using " " is incorrect. As far as I know, in Java, when you read data from an input stream (like FileInputStream), if it has already reached the end of the data source (meaning there is no more data to read), the read() method will return -1. This is standard behavior in Java I/O, not something introduced in a specific version.

The original poster made an error in their code by not saving the value being read with fileInputStream.read() != -1. Their code was something like this:

while(fileInputStream.read() != -1) { // this line reads a bit of data
   value = fileInputStream.read(); // this line reads a bit of data and saves it
   // rest of code
}

which means they were reading from the stream 2 times each loop cycle but only saving the data from the read() method one time. This would result in half the data being lost. When they changed it to:

while(fileInputStream.available() > 0) {
   value = fileInputStream.read(); // this line reads a bit of data and saves it
   // rest of code
}

The code passed because now because only 1 line reads the data and saves it and no data is lost. Their conclusion that you must use .available() > 0 was incorrect as they just had a logical error in their original code. You might be commenting on the wrong post because no one has mentioned using " ".

Haha, I didn’t reply to the wrong post. I just forgot to paste the code inside that quote. I have the same opinion as you. Thank you for your reply.

Ahhh. I see 🙃🙂🙃