Chapter 18
The java.util.zip Package

CheckedOutputStream

Name

CheckedOutputStream

Synopsis

Class Name:

java.util.zip.CheckedOutputStream

Superclass:

java.io.FilterOutputStream

Immediate Subclasses:

None

Interfaces Implemented:

None

Availability:

New as of JDK 1.1

The CheckOutputStream class represents an OutputStream with an associated checksum. In other words, a CheckedOutputStream wraps a regular output stream and computes a checksum value as data is written to the stream. The checksum can verify the integrity of the data. When you create a CheckedOutputStream, you must specify an object that implements the Checksum interface that computes the checksum.

Class Summary

public class java.util.zip.CheckedOutputStream
             extends java.io.FilterOutputStream {
  // Constructors
  public CheckedOutputStream(OutputStream out, Checksum cksum);
  
  // Instance Methods
  public Checksum getChecksum();
  public void write(int b);
  public void write(byte[] b, int off, int len);
}

Constructors

CheckedOutputStream

public CheckedOutputStream(OutputStream out, Checksum cksum)

Parameters

out

The underlying output stream.

cksum

The checksum object.

Description

This constructor creates a CheckedOutputStream that writes data to the given OutputStream and updates the given Checksum.

Instance Methods

getChecksum

public Checksum getChecksum()

Returns

The Checksum associated with this output stream.

Description

This method returns the Checksum object associated with this output stream.

write

public void write(int b) throws IOException

Parameters

b: The value to write.

Throws

IOException: If any kind of I/O error occurs.

Overrides

FilterOutputStream.write(int)

Description

This method writes a byte that contains the lowest eight bits of the given integer value to the underlying OutputStream and then updates the checksum.

public void write(byte[] b, int off, int len) throws IOException

Parameters

b

An array of bytes to write to the stream.

off

An offset into the byte array.

len

The number of bytes to write.

Throws

IOException: If any kind of I/O error occurs.

Overrides

FilterOutputStream.write(byte[], int, int)

Description

This method writes len bytes to the underlying OutputStream from the given array, starting at off. The checksum is then updated with the data that has been written.

Inherited Methods

Method	Inherited From	Method	Inherited From
`clone()`	`Object`	`close()`	`FilterOutputStream`
`equals(Object)`	`Object`	`finalize()`	`Object`
`flush()`	`FilterOutputStream`	`getClass()`	`Object`
`hashCode()`	`Object`	`notify()`	`Object`
`notifyAll()`	`Object`	`toString()`	`Object`
`wait()`	`Object`	`wait(long)`	`Object`
`wait(long, int)`	`Object`	`write(byte[])`	`FilterOutputStream`