Java，需要一个while循环才能达到eof。iewhile !eof, 继续解析
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Java, need a while loop to reach eof. i.e.while !eof, keep parsing
提问by john stamos
I currently have a working parser. It parses a file once(not what I want it to do) and then outputs parsed data into a file. I need it to keep parsing and appending to the same output file until the end of the input file. Looks something like this.
我目前有一个工作解析器。它解析一个文件一次（不是我想要它做的），然后将解析的数据输出到一个文件中。我需要它继续解析并附加到同一个输出文件，直到输入文件结束。看起来像这样。
try {
// my code parsing the data and appending to eof of output. (works)
}
catch (EOFException eof){
}
Everything is done except the while loop. It only parses once when I need it to keep parsing. I'm looking for a while loop function to reach eof.
除了while循环之外，一切都完成了。它只在我需要它继续解析时解析一次。我正在寻找一个 while 循环函数来达到 eof。
I'm also using a DataInputStream. Is there some sort of DataInputStream.hasNext function?
我也在使用 DataInputStream。是否有某种 DataInputStream.hasNext 函数？
DataInputStream dis = new DataInputStream(new FileInputStream(inFile));
i.e. dis.read();
.
.
//Need a while !eof while loop
try {
// my code parsing the data and appending to eof of output. (works)
}
catch (EOFException eof){
}
回答by FThompson
Instead of looping until an EOFException is thrown, you could take a much cleaner approach, and use available().
您可以采用更简洁的方法，而不是循环直到抛出 EOFException ，并使用available().
DataInputStream dis = new DataInputStream(new FileInputStream(inFile));
while (dis.available() > 0) {
// read and use data
}
Alternatively, if you choose to take the EOF approach, you would want to set a boolean upon the exception being caught, and use that boolean in your loop, but I do not recommend it:
或者，如果您选择采用 EOF 方法，您可能希望在捕获异常时设置一个布尔值，并在循环中使用该布尔值，但我不建议这样做：
DataInputStream dis = new DataInputStream(new FileInputStream(inFile));
boolean eof = false;
while (!eof) {
try {
// read and use data
} catch (EOFException e) {
eof = true;
}
}
回答by Ravi Thapliyal
DataInputStreamhas a lot of readXXX()methods that do throw EOFExceptionbut the method that you're using DataInputStream.read()does notthrow EOFException.
DataInputStream有很多readXXX()方法可以 throwEOFException但您使用的方法DataInputStream.read()不会throw EOFException。
To correctly identify the EOF while using read()implement your whileloop as follows
要在使用时正确识别 EOF，read()请while按如下方式实现您的循环
int read = 0;
byte[] b = new byte[1024];
while ((read = dis.read(b)) != -1) { // returns numOfBytesRead or -1 at EOF
// parse, or write to output stream as
dos.write(b, 0, read); // (byte[], offset, numOfBytesToWrite)
}
回答by BuvinJ
If you are using FileInputStream, here's an EOF method for a class that has a FileInputStream member called fis.
如果您正在使用FileInputStream，这里有一个 EOF 方法，用于具有名为 的 FileInputStream 成员的类fis。
public boolean isEOF()
{
try { return fis.getChannel().position() >= fis.getChannel().size()-1; }
catch (IOException e) { return true; }
}
