public class FileInputStream extends InputStream
FileInputStream obtains input bytes from a file in a file system. What files are available depends on
the host environment.
FileInputStream is meant for reading streams of raw bytes such as image data. For reading streams of
characters, consider using FileReader.
File,
FileOutputStream| Constructor and Description |
|---|
FileInputStream(File file)
Creates a
FileInputStream by opening a connection to an actual file, the file named by the
File object file in the file system. |
FileInputStream(String name)
Creates a
FileInputStream by opening a connection to an actual file, the file named by the path name
name in the file system. |
| Modifier and Type | Method and Description |
|---|---|
int |
available()
Returns an estimate of the number of remaining bytes that can be read (or skipped over) from this input stream
without blocking by the next invocation of a method for this input stream.
|
void |
close()
Closes this file input stream and releases any system resources associated with the stream.
|
int |
read()
Reads a byte of data from this input stream.
|
int |
read(byte[] b)
Reads up to
b.length bytes of data from this input stream into an array of bytes. |
int |
read(byte[] b,
int off,
int len)
Reads up to
len bytes of data from this input stream into an array of bytes. |
long |
skip(long n)
Skips over and discards
n bytes of data from the input stream. |
mark, markSupported, resetpublic FileInputStream(File file) throws FileNotFoundException
FileInputStream by opening a connection to an actual file, the file named by the
File object file in the file system.
First, if there is a security manager, its checkRead method is called with the path represented by
the file argument as its argument.
If the named file does not exist, is a directory rather than a regular file, or for some other reason cannot be
opened for reading then a FileNotFoundException is thrown.
file - the file to be opened for reading.FileNotFoundException - if the file does not exist, is a directory rather than a regular file, or for some other reason
cannot be opened for reading.SecurityException - if a security manager exists and its checkRead method denies read access to the file.File.getPath()public FileInputStream(String name) throws FileNotFoundException
FileInputStream by opening a connection to an actual file, the file named by the path name
name in the file system.
First, if there is a security manager, its checkRead method is called with the name
argument as its argument.
If the named file does not exist, is a directory rather than a regular file, or for some other reason cannot be
opened for reading then a FileNotFoundException is thrown.
name - the system-dependent file name.FileNotFoundException - if the file does not exist, is a directory rather than a regular file, or for some other reason
cannot be opened for reading.SecurityException - if a security manager exists and its checkRead method denies read access to the file.public int available()
throws IOException
In some cases, a non-blocking read (or skip) may appear to be blocked when it is merely slow, for example when reading large files over slow networks.
available in class InputStreamIOException - if this file input stream has been closed by calling close or an I/O error occurs.public void close()
throws IOException
If this stream has an associated channel then the channel is closed as well.
close in interface Closeableclose in interface AutoCloseableclose in class InputStreamIOException - if an I/O error occurs.public int read()
throws IOException
read in class InputStream-1 if the end of the file is reached.IOException - if an I/O error occurs.public int read(byte[] b)
throws IOException
b.length bytes of data from this input stream into an array of bytes. This method blocks
until some input is available.read in class InputStreamb - the buffer into which the data is read.-1 if there is no more data because the
end of the file has been reached.IOException - if an I/O error occurs.InputStream.read(byte[], int, int)public int read(byte[] b,
int off,
int len)
throws IOException
len bytes of data from this input stream into an array of bytes. If len is
not zero, the method blocks until some input is available; otherwise, no bytes are read and 0 is
returned.read in class InputStreamb - the buffer into which the data is read.off - the start offset in the destination array blen - the maximum number of bytes read.-1 if there is no more data because the
end of the file has been reached.NullPointerException - If b is null.IndexOutOfBoundsException - If off is negative, len is negative, or len is greater than
b.length - offIOException - if an I/O error occurs.InputStream.read()public long skip(long n)
throws IOException
n bytes of data from the input stream.
The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes,
possibly 0. If n is negative, the method will try to skip backwards. In case the
backing file does not support backward skip at its current position, an IOException is thrown. The
actual number of bytes skipped is returned. If it skips forwards, it returns a positive value. If it skips
backwards, it returns a negative value.
This method may skip more bytes than what are remaining in the backing file. This produces no exception and the number of bytes skipped may include some number of bytes that were beyond the EOF of the backing file. Attempting to read from the stream after skipping past the end will result in -1 indicating the end of the file.
skip in class InputStreamn - the number of bytes to be skipped.IOException - if n is negative, if the stream does not support seek, or if an I/O error occurs.