FileReader rd=new FileReader("new.mp4"); FileWriter wr=new FileWriter("output.mp4"); int ch; while((ch=rd.read())!=-1) wr.write(ch); wr.flush(); wr.close();
When I use the FileReader
and FileWriter
to read and write an mp4 file, the output.mp4
file can't be rendered well. But when I use FileInputStream
and FileOutputStream
instead it worked well.
So can I conclude FileReader
and FileWriter
are only for reading and writing text?
A BufferedInputStream reads from another InputStream , but a FileInputStream reads from a file1.
InputStream − This is used to read (sequential) data from a source. OutputStream − This is used to write data to a destination.
FileReader is used to read a file from a disk drive whereas BufferedReader is not bound to only reading files. It can be used to read data from any character stream.
FileInputStream class is useful to read data from a file in the form of sequence of bytes. FileInputStream is meant for reading streams of raw bytes such as image data. For reading streams of characters, consider using FileReader.
Yes, your conclusion is correct subclasses of Reader
and Writer
are for reading/writing text content. InputStream
/ OutputStream
are for binary content. If you take a look at the documentation:
Reader
- Abstract class for reading character streams
InputStream
- Abstract class is the superclass of all classes representing an input stream of bytes.
FileReader
(and indeed anything extending Reader) is indeed for text. From the documentation of Reader
:
Abstract class for reading character streams.
(Emphasis mine.) Look at the API and you'll see it's all to do with text - char
instead of byte
all over the place.
InputStream
and OutputStream
are for binary data, such as mp4 files.
Personally I would avoid FileReader
altogether though, as it always uses the system default character encoding - at least before Java 11. Instead, use InputStreamReader
around a FileInputStream
... but only when you want to deal with text. (Alternatively, use Files.newBufferedReader
.)
As an aside, that's a very inefficient way of copying from an input to an output... use the overloads of read
and write
which read into or write from a buffer - either a byte[]
or a char[]
. Otherwise you're calling read and write for every single byte/character in the file.
You should also close IO streams in finally
blocks so they're closed even if an exception is thrown while you're processing them.
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