Returns the number of bytes that can be read from this input stream without blocking.

This method simply performs in.available() and returns the result.

Closes this input stream and releases any system resources associated with the stream. This method simply performs in.close().

Indicates whether some other object is "equal to" this one.

The equals method implements an equivalence relation on non-null object references:

• It is reflexive: for any non-null reference value x, x.equals(x) should return true.
• It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
• It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
• It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
• For any non-null reference value x, x.equals(null) should return false.

The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any non-null reference values x and y, this method returns true if and only if x and y refer to the same object (x == y has the value true).

Note that it is generally necessary to override the hashCode method whenever this method is overridden, so as to maintain the general contract for the hashCode method, which states that equal objects must have equal hash codes.

Returns the runtime class of an object. That Class object is the object that is locked by static synchronized methods of the represented class.

Returns a hash code value for the object. This method is supported for the benefit of hashtables such as those provided by java.util.Hashtable.

The general contract of hashCode is:

• Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
• If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.
• It is not required that if two objects are unequal according to the method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hashtables.

As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the Java^TM programming language.)

Marks the current position in this input stream. A subsequent call to the reset method repositions this stream at the last marked position so that subsequent reads re-read the same bytes.

The readlimit argument tells this input stream to allow that many bytes to be read before the mark position gets invalidated.

This method simply performs in.mark(readlimit).

Tests if this input stream supports the mark and reset methods. This method simply performs in.markSupported().

Wakes up a single thread that is waiting on this object's monitor. If any threads are waiting on this object, one of them is chosen to be awakened. The choice is arbitrary and occurs at the discretion of the implementation. A thread waits on an object's monitor by calling one of the wait methods.

The awakened thread will not be able to proceed until the current thread relinquishes the lock on this object. The awakened thread will compete in the usual manner with any other threads that might be actively competing to synchronize on this object; for example, the awakened thread enjoys no reliable privilege or disadvantage in being the next thread to lock this object.

This method should only be called by a thread that is the owner of this object's monitor. A thread becomes the owner of the object's monitor in one of three ways:

• By executing a synchronized instance method of that object.
• By executing the body of a synchronized statement that synchronizes on the object.
• For objects of type Class, by executing a synchronized static method of that class.

Only one thread at a time can own an object's monitor.

Wakes up all threads that are waiting on this object's monitor. A thread waits on an object's monitor by calling one of the wait methods.

The awakened threads will not be able to proceed until the current thread relinquishes the lock on this object. The awakened threads will compete in the usual manner with any other threads that might be actively competing to synchronize on this object; for example, the awakened threads enjoy no reliable privilege or disadvantage in being the next thread to lock this object.

This method should only be called by a thread that is the owner of this object's monitor. See the notify method for a description of the ways in which a thread can become the owner of a monitor.

Reads the next byte of data from this input stream. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

This method simply performs in.read() and returns the result.

Reads some number of bytes from the contained input stream and stores them into the buffer array b. The number of bytes actually read is returned as an integer. This method blocks until input data is available, end of file is detected, or an exception is thrown.

If b is null, a NullPointerException is thrown. If the length of b is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is read and stored into b.

The first byte read is stored into element b[0], the next one into b[1], and so on. The number of bytes read is, at most, equal to the length of b. Let k be the number of bytes actually read; these bytes will be stored in elements b[0] through b[k-1], leaving elements b[k] through b[b.length-1] unaffected.

If the first byte cannot be read for any reason other than end of file, then an IOException is thrown. In particular, an IOException is thrown if the input stream has been closed.

The read(b) method has the same effect as:

 read(b, 0, b.length) 
 

Reads up to len bytes of data from the contained input stream into an array of bytes. An attempt is made to read as many as len bytes, but a smaller number may be read, possibly zero. The number of bytes actually read is returned as an integer.

This method blocks until input data is available, end of file is detected, or an exception is thrown.

If b is null, a NullPointerException is thrown.

If off is negative, or len is negative, or off+len is greater than the length of the array b, then an IndexOutOfBoundsException is thrown.

If len is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is read and stored into b.

The first byte read is stored into element b[off], the next one into b[off+1], and so on. The number of bytes read is, at most, equal to len. Let k be the number of bytes actually read; these bytes will be stored in elements b[off] through b[off+k-1], leaving elements b[off+k] through b[off+len-1] unaffected.

In every case, elements b[0] through b[off] and elements b[off+len] through b[b.length-1] are unaffected.

If the first byte cannot be read for any reason other than end of file, then an IOException is thrown. In particular, an IOException is thrown if the input stream has been closed.

Reads one input byte and returns true if that byte is nonzero, false if that byte is zero. This method is suitable for reading the byte written by the writeBoolean method of interface DataOutput.

Reads and returns one input byte. The byte is treated as a signed value in the range -128 through 127, inclusive. This method is suitable for reading the byte written by the writeByte method of interface DataOutput.

Reads an input char and returns the char value. A Unicode char is made up of two bytes. Let a be the first byte read and b be the second byte. The value returned is:

(char)((a << 8) | (b & 0xff))
 

This method is suitable for reading bytes written by the writeChar method of interface DataOutput.

Reads eight input bytes and returns a double value. It does this by first constructing a long value in exactly the manner of the readlong method, then converting this long value to a double in exactly the manner of the method Double.longBitsToDouble. This method is suitable for reading bytes written by the writeDouble method of interface DataOutput.

Reads four input bytes and returns a float value. It does this by first constructing an int value in exactly the manner of the readInt method, then converting this int value to a float in exactly the manner of the method Float.intBitsToFloat. This method is suitable for reading bytes written by the writeFloat method of interface DataOutput.

Reads some bytes from an input stream and stores them into the buffer array b. The number of bytes read is equal to the length of b.

This method blocks until one of the following conditions occurs:

• b.length bytes of input data are available, in which case a normal return is made.
• End of file is detected, in which case an EOFException is thrown.
• An I/O error occurs, in which case an IOException other than EOFException is thrown.

If b is null, a NullPointerException is thrown. If b.length is zero, then no bytes are read. Otherwise, the first byte read is stored into element b[0], the next one into b[1], and so on. If an exception is thrown from this method, then it may be that some but not all bytes of b have been updated with data from the input stream.

Reads len bytes from an input stream.

This method blocks until one of the following conditions occurs:

• len bytes of input data are available, in which case a normal return is made.
• End of file is detected, in which case an EOFException is thrown.
• An I/O error occurs, in which case an IOException other than EOFException is thrown.

If b is null, a NullPointerException is thrown. If off is negative, or len is negative, or off+len is greater than the length of the array b, then an IndexOutOfBoundsException is thrown. If len is zero, then no bytes are read. Otherwise, the first byte read is stored into element b[off], the next one into b[off+1], and so on. The number of bytes read is, at most, equal to len.

Reads four input bytes and returns an int value. Let a be the first byte read, b be the second byte, c be the third byte, and d be the fourth byte. The value returned is:

 
 (((a & 0xff) << 24) | ((b & 0xff) << 16) |
  ((c & 0xff) << 8) | (d & 0xff))
 

This method is suitable for reading bytes written by the writeInt method of interface DataOutput.

Reads the next line of text from the input stream. It reads successive bytes, converting each byte separately into a character, until it encounters a line terminator or end of file; the characters read are then returned as a String. Note that because this method processes bytes, it does not support input of the full Unicode character set.

If end of file is encountered before even one byte can be read, then null is returned. Otherwise, each byte that is read is converted to type char by zero-extension. If the character '\n' is encountered, it is discarded and reading ceases. If the character '\r' is encountered, it is discarded and, if the following byte converts to the character '\n', then that is discarded also; reading then ceases. If end of file is encountered before either of the characters '\n' and '\r' is encountered, reading ceases. Once reading has ceased, a String is returned that contains all the characters read and not discarded, taken in order. Note that every character in this string will have a value less than \u0100, that is, (char)256.

Reads eight input bytes and returns a long value. Let a be the first byte read, b be the second byte, c be the third byte, d be the fourth byte, e be the fifth byte, f be the sixth byte, g be the seventh byte, and h be the eighth byte. The value returned is:

 
 (((long)(a & 0xff) << 56) |
  ((long)(b & 0xff) << 48) |
  ((long)(c & 0xff) << 40) |
  ((long)(d & 0xff) << 32) |
  ((long)(e & 0xff) << 24) |
  ((long)(f & 0xff) << 16) |
  ((long)(g & 0xff) <<  8) |
  ((long)(h & 0xff)))
 

This method is suitable for reading bytes written by the writeLong method of interface DataOutput.

Reads two input bytes and returns a short value. Let a be the first byte read and b be the second byte. The value returned is:

(short)((a << 8) | (b & 0xff))
 

This method is suitable for reading the bytes written by the writeShort method of interface DataOutput.

Reads one input byte, zero-extends it to type int, and returns the result, which is therefore in the range 0 through 255. This method is suitable for reading the byte written by the writeByte method of interface DataOutput if the argument to writeByte was intended to be a value in the range 0 through 255.

Reads two input bytes and returns an int value in the range 0 through 65535. Let a be the first byte read and b be the second byte. The value returned is:

(((a & 0xff) << 8) | (b & 0xff))
 

This method is suitable for reading the bytes written by the writeShort method of interface DataOutput if the argument to writeShort was intended to be a value in the range 0 through 65535.

Reads in a string that has been encoded using a modified UTF-8 format. The general contract of readUTF is that it reads a representation of a Unicode character string encoded in modified UTF-8 format; this string of characters is then returned as a String.

First, two bytes are read and used to construct an unsigned 16-bit integer in exactly the manner of the readUnsignedShort method . This integer value is called the UTF length and specifies the number of additional bytes to be read. These bytes are then converted to characters by considering them in groups. The length of each group is computed from the value of the first byte of the group. The byte following a group, if any, is the first byte of the next group.

If the first byte of a group matches the bit pattern 0xxxxxxx (where x means "may be 0 or 1"), then the group consists of just that byte. The byte is zero-extended to form a character.

If the first byte of a group matches the bit pattern 110xxxxx, then the group consists of that byte a and a second byte b. If there is no byte b (because byte a was the last of the bytes to be read), or if byte b does not match the bit pattern 10xxxxxx, then a UTFDataFormatException is thrown. Otherwise, the group is converted to the character:

(char)(((a& 0x1F) << 6) | (b & 0x3F))
 

If the first byte of a group matches the bit pattern 1110xxxx, then the group consists of that byte a and two more bytes b and c. If there is no byte c (because byte a was one of the last two of the bytes to be read), or either byte b or byte c does not match the bit pattern 10xxxxxx, then a UTFDataFormatException is thrown. Otherwise, the group is converted to the character:

 (char)(((a & 0x0F) << 12) | ((b & 0x3F) << 6) | (c & 0x3F))
 

If the first byte of a group matches the pattern 1111xxxx or the pattern 10xxxxxx, then a UTFDataFormatException is thrown.

If end of file is encountered at any time during this entire process, then an EOFException is thrown.

After every group has been converted to a character by this process, the characters are gathered, in the same order in which their corresponding groups were read from the input stream, to form a String, which is returned.

The writeUTF method of interface DataOutput may be used to write data that is suitable for reading by this method.

Reads from the stream in a representation of a Unicode character string encoded in modified UTF-8 format; this string of characters is then returned as a String. The details of the modified UTF-8 representation are exactly the same as for the readUTF method of DataInput.

Repositions this stream to the position at the time the mark method was last called on this input stream.

This method simply performs in.reset().

Stream marks are intended to be used in situations where you need to read ahead a little to see what's in the stream. Often this is most easily done by invoking some general parser. If the stream is of the type handled by the parse, it just chugs along happily. If the stream is not of that type, the parser should toss an exception when it fails. If this happens within readlimit bytes, it allows the outer code to reset the stream and try another parser.

Skips over and discards 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. The actual number of bytes skipped is returned.

This method simply performs in.skip(n).

Makes an attempt to skip over n bytes of data from the input stream, discarding the skipped bytes. However, it may skip over some smaller number of bytes, possibly zero. This may result from any of a number of conditions; reaching end of file before n bytes have been skipped is only one possibility. This method never throws an EOFException. The actual number of bytes skipped is returned.

Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.

The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:

 getClass().getName() + '@' + Integer.toHexString(hashCode())
 

Causes current thread to wait until another thread invokes the method or the method for this object. In other words, this method behaves exactly as if it simply performs the call wait(0).

The current thread must own this object's monitor. The thread releases ownership of this monitor and waits until another thread notifies threads waiting on this object's monitor to wake up either through a call to the notify method or the notifyAll method. The thread then waits until it can re-obtain ownership of the monitor and resumes execution.

As in the one argument version, interrupts and spurious wakeups are possible, and this method should always be used in a loop:

     synchronized (obj) {
         while (<condition does not hold>)
             obj.wait();
         ... // Perform action appropriate to condition
     }
 

This method should only be called by a thread that is the owner of this object's monitor. See the notify method for a description of the ways in which a thread can become the owner of a monitor.

Causes current thread to wait until either another thread invokes the method or the method for this object, or a specified amount of time has elapsed.

The current thread must own this object's monitor.

This method causes the current thread (call it T) to place itself in the wait set for this object and then to relinquish any and all synchronization claims on this object. Thread T becomes disabled for thread scheduling purposes and lies dormant until one of four things happens:

• Some other thread invokes the notify method for this object and thread T happens to be arbitrarily chosen as the thread to be awakened.
• Some other thread invokes the notifyAll method for this object.
• Some other thread interrupts thread T.
• The specified amount of real time has elapsed, more or less. If timeout is zero, however, then real time is not taken into consideration and the thread simply waits until notified.

The thread T is then removed from the wait set for this object and re-enabled for thread scheduling. It then competes in the usual manner with other threads for the right to synchronize on the object; once it has gained control of the object, all its synchronization claims on the object are restored to the status quo ante - that is, to the situation as of the time that the wait method was invoked. Thread T then returns from the invocation of the wait method. Thus, on return from the wait method, the synchronization state of the object and of thread T is exactly as it was when the wait method was invoked.

A thread can also wake up without being notified, interrupted, or timing out, a so-called spurious wakeup. While this will rarely occur in practice, applications must guard against it by testing for the condition that should have caused the thread to be awakened, and continuing to wait if the condition is not satisfied. In other words, waits should always occur in loops, like this one:

     synchronized (obj) {
         while (<condition does not hold>)
             obj.wait(timeout);
         ... // Perform action appropriate to condition
     }
 

(For more information on this topic, see Section 3.2.3 in Doug Lea's "Concurrent Programming in Java (Second Edition)" (Addison-Wesley, 2000), or Item 50 in Joshua Bloch's "Effective Java Programming Language Guide" (Addison-Wesley, 2001).

If the current thread is interrupted by another thread while it is waiting, then an InterruptedException is thrown. This exception is not thrown until the lock status of this object has been restored as described above.

Note that the wait method, as it places the current thread into the wait set for this object, unlocks only this object; any other objects on which the current thread may be synchronized remain locked while the thread waits.

This method should only be called by a thread that is the owner of this object's monitor. See the notify method for a description of the ways in which a thread can become the owner of a monitor.

Causes current thread to wait until another thread invokes the method or the method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed.

This method is similar to the wait method of one argument, but it allows finer control over the amount of time to wait for a notification before giving up. The amount of real time, measured in nanoseconds, is given by:

 1000000*timeout+nanos

In all other respects, this method does the same thing as the method of one argument. In particular, wait(0, 0) means the same thing as wait(0).

The current thread must own this object's monitor. The thread releases ownership of this monitor and waits until either of the following two conditions has occurred:

• Another thread notifies threads waiting on this object's monitor to wake up either through a call to the notify method or the notifyAll method.
• The timeout period, specified by timeout milliseconds plus nanos nanoseconds arguments, has elapsed.

The thread then waits until it can re-obtain ownership of the monitor and resumes execution.

As in the one argument version, interrupts and spurious wakeups are possible, and this method should always be used in a loop:

     synchronized (obj) {
         while (<condition does not hold>)
             obj.wait(timeout, nanos);
         ... // Perform action appropriate to condition
     }
 

This method should only be called by a thread that is the owner of this object's monitor. See the notify method for a description of the ways in which a thread can become the owner of a monitor.