223 * Reads a byte of data from this input stream. This method blocks
224 * if no input is yet available.
225 *
226 * @return the next byte of data, or <code>-1</code> if the end of the
227 * file is reached.
228 * @exception IOException if an I/O error occurs.
229 */
230 public int read() throws IOException {
231 return read0();
232 }
233
234 private native int read0() throws IOException;
235
236 /**
237 * Reads a subarray as a sequence of bytes.
238 * @param b the data to be written
239 * @param off the start offset in the data
240 * @param len the number of bytes that are written
241 * @exception IOException If an I/O error has occurred.
242 */
243 private native int readBytes(byte b[], int off, int len) throws IOException;
244
245 /**
246 * Reads up to <code>b.length</code> bytes of data from this input
247 * stream into an array of bytes. This method blocks until some input
248 * is available.
249 *
250 * @param b the buffer into which the data is read.
251 * @return the total number of bytes read into the buffer, or
252 * <code>-1</code> if there is no more data because the end of
253 * the file has been reached.
254 * @exception IOException if an I/O error occurs.
255 */
256 public int read(byte b[]) throws IOException {
257 return readBytes(b, 0, b.length);
258 }
259
260 /**
261 * Reads up to <code>len</code> bytes of data from this input stream
262 * into an array of bytes. If <code>len</code> is not zero, the method
263 * blocks until some input is available; otherwise, no
264 * bytes are read and <code>0</code> is returned.
265 *
266 * @param b the buffer into which the data is read.
267 * @param off the start offset in the destination array <code>b</code>
268 * @param len the maximum number of bytes read.
269 * @return the total number of bytes read into the buffer, or
270 * <code>-1</code> if there is no more data because the end of
271 * the file has been reached.
272 * @exception NullPointerException If <code>b</code> is <code>null</code>.
273 * @exception IndexOutOfBoundsException If <code>off</code> is negative,
274 * <code>len</code> is negative, or <code>len</code> is greater than
275 * <code>b.length - off</code>
276 * @exception IOException if an I/O error occurs.
277 */
278 public int read(byte b[], int off, int len) throws IOException {
279 return readBytes(b, off, len);
280 }
281
282 /**
283 * Skips over and discards <code>n</code> bytes of data from the
284 * input stream.
285 *
286 * <p>The <code>skip</code> method may, for a variety of
287 * reasons, end up skipping over some smaller number of bytes,
288 * possibly <code>0</code>. If <code>n</code> is negative, the method
289 * will try to skip backwards. In case the backing file does not support
290 * backward skip at its current position, an <code>IOException</code> is
291 * thrown. The actual number of bytes skipped is returned. If it skips
292 * forwards, it returns a positive value. If it skips backwards, it
293 * returns a negative value.
294 *
295 * <p>This method may skip more bytes than what are remaining in the
296 * backing file. This produces no exception and the number of bytes skipped
297 * may include some number of bytes that were beyond the EOF of the
298 * backing file. Attempting to read from the stream after skipping past
|
223 * Reads a byte of data from this input stream. This method blocks
224 * if no input is yet available.
225 *
226 * @return the next byte of data, or <code>-1</code> if the end of the
227 * file is reached.
228 * @exception IOException if an I/O error occurs.
229 */
230 public int read() throws IOException {
231 return read0();
232 }
233
234 private native int read0() throws IOException;
235
236 /**
237 * Reads a subarray as a sequence of bytes.
238 * @param b the data to be written
239 * @param off the start offset in the data
240 * @param len the number of bytes that are written
241 * @exception IOException If an I/O error has occurred.
242 */
243 private native int readBytes(byte[] b, int off, int len) throws IOException;
244
245 /**
246 * Reads up to <code>b.length</code> bytes of data from this input
247 * stream into an array of bytes. This method blocks until some input
248 * is available.
249 *
250 * @param b the buffer into which the data is read.
251 * @return the total number of bytes read into the buffer, or
252 * <code>-1</code> if there is no more data because the end of
253 * the file has been reached.
254 * @exception IOException if an I/O error occurs.
255 */
256 public int read(byte[] b) throws IOException {
257 return readBytes(b, 0, b.length);
258 }
259
260 /**
261 * Reads up to <code>len</code> bytes of data from this input stream
262 * into an array of bytes. If <code>len</code> is not zero, the method
263 * blocks until some input is available; otherwise, no
264 * bytes are read and <code>0</code> is returned.
265 *
266 * @param b the buffer into which the data is read.
267 * @param off the start offset in the destination array <code>b</code>
268 * @param len the maximum number of bytes read.
269 * @return the total number of bytes read into the buffer, or
270 * <code>-1</code> if there is no more data because the end of
271 * the file has been reached.
272 * @exception NullPointerException If <code>b</code> is <code>null</code>.
273 * @exception IndexOutOfBoundsException If <code>off</code> is negative,
274 * <code>len</code> is negative, or <code>len</code> is greater than
275 * <code>b.length - off</code>
276 * @exception IOException if an I/O error occurs.
277 */
278 public int read(byte[] b, int off, int len) throws IOException {
279 return readBytes(b, off, len);
280 }
281
282 /**
283 * Skips over and discards <code>n</code> bytes of data from the
284 * input stream.
285 *
286 * <p>The <code>skip</code> method may, for a variety of
287 * reasons, end up skipping over some smaller number of bytes,
288 * possibly <code>0</code>. If <code>n</code> is negative, the method
289 * will try to skip backwards. In case the backing file does not support
290 * backward skip at its current position, an <code>IOException</code> is
291 * thrown. The actual number of bytes skipped is returned. If it skips
292 * forwards, it returns a positive value. If it skips backwards, it
293 * returns a negative value.
294 *
295 * <p>This method may skip more bytes than what are remaining in the
296 * backing file. This produces no exception and the number of bytes skipped
297 * may include some number of bytes that were beyond the EOF of the
298 * backing file. Attempting to read from the stream after skipping past
|