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| 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

## Description

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`

## See Also

`Checksum`, `FilterOutputStream`, `IOException`, `OutputStream`

CheckedInputStream |  | Checksum