ObjectInput

AI-generated Key Takeaways

• The ObjectInput interface defines methods for reading serialized objects from a stream.

• It extends the DataInput and AutoCloseable interfaces, inheriting methods for reading primitive data types and closing the stream.

• The readObject() method is central to this interface, allowing the reading of complete objects from the stream.

• Methods like read(), skip(), and available() provide control over the reading process, enabling byte-by-byte reading, skipping bytes, and checking for available data.

• The interface handles potential exceptions like IOException for stream errors and ClassNotFoundException if the object's class is not found during deserialization.

public interface ObjectInput implements DataInput AutoCloseable

Known Indirect Subclasses ObjectInputStream ObjectInputStream An ObjectInputStream deserializes primitive data and objects previously written using an ObjectOutputStream.

Defines an interface for classes that allow reading serialized objects.

See Also

• ObjectInputStream
• ObjectOutput

Public Method Summary

abstract int	available() Indicates the number of bytes of primitive data that can be read without blocking.
abstract void	close() Closes this stream.
abstract int	read() Reads a single byte from this stream and returns it as an integer in the range from 0 to 255.
abstract int	read(byte[] buffer, int offset, int count) Reads at most count bytes from this stream and stores them in byte array buffer starting at offset count.
abstract int	read(byte[] buffer) Reads bytes from this stream into the byte array buffer.
abstract Object	readObject() Reads the next object from this stream.
abstract long	skip(long byteCount) Skips byteCount bytes on this stream.

Inherited Method Summary

From interface java.io.DataInput

abstract boolean	readBoolean() Reads one input byte and returns true if that byte is nonzero, false if that byte is zero.
abstract byte	readByte() Reads and returns one input byte.
abstract char	readChar() Reads two input bytes and returns a char value.
abstract double	readDouble() Reads eight input bytes and returns a double value.
abstract float	readFloat() Reads four input bytes and returns a float value.
abstract void	readFully(byte[] b) Reads some bytes from an input stream and stores them into the buffer array b.
abstract void	readFully(byte[] b, int off, int len) Reads len bytes from an input stream.
abstract int	readInt() Reads four input bytes and returns an int value.
abstract String	readLine() Reads the next line of text from the input stream.
abstract long	readLong() Reads eight input bytes and returns a long value.
abstract short	readShort() Reads two input bytes and returns a short value.
abstract String	readUTF() Reads in a string that has been encoded using a modified UTF-8 format.
abstract int	readUnsignedByte() Reads one input byte, zero-extends it to type int, and returns the result, which is therefore in the range 0 through 255.
abstract int	readUnsignedShort() Reads two input bytes and returns an int value in the range 0 through 65535.
abstract int	skipBytes(int n) Makes an attempt to skip over n bytes of data from the input stream, discarding the skipped bytes.

From interface java.lang.AutoCloseable

abstract void

close() Closes this resource, relinquishing any underlying resources.

Public Methods

public abstract int available ()

Indicates the number of bytes of primitive data that can be read without blocking.

Returns

• the number of bytes available.

Throws

IOException	if an I/O error occurs.

public abstract void close ()

Closes this stream. Implementations of this method should free any resources used by the stream.

Throws

IOException	if an I/O error occurs while closing the input stream.

public abstract int read ()

Reads a single byte from this stream and returns it as an integer in the range from 0 to 255. Returns -1 if the end of this stream has been reached. Blocks if no input is available.

Returns

• the byte read or -1 if the end of this stream has been reached.

Throws

IOException	if this stream is closed or another I/O error occurs.

public abstract int read (byte[] buffer, int offset, int count)

Reads at most count bytes from this stream and stores them in byte array buffer starting at offset count. Blocks while waiting for input.

Parameters

buffer	the array in which to store the bytes read.
offset	the initial position in buffer to store the bytes read from this stream.
count	the maximum number of bytes to store in buffer.

Returns

• the number of bytes read or -1 if the end of this stream has been reached.

Throws

IOException	if this stream is closed or another I/O error occurs.

public abstract int read (byte[] buffer)

Reads bytes from this stream into the byte array buffer. Blocks while waiting for input.

Parameters

buffer	the array in which to store the bytes read.

Returns

• the number of bytes read or -1 if the end of this stream has been reached.

Throws

IOException	if this stream is closed or another I/O error occurs.

public abstract Object readObject ()

Reads the next object from this stream.

Returns

• the object read.

Throws

ClassNotFoundException	if the object's class cannot be found.
IOException	if this stream is closed or another I/O error occurs.

public abstract long skip (long byteCount)

Skips byteCount bytes on this stream. Less than byteCount byte are skipped if the end of this stream is reached before the operation completes.

Parameters

byteCount

Returns

• the number of bytes actually skipped.

Throws

IOException	if this stream is closed or another I/O error occurs.