Chapter 18
The java.util.zip Package

ZipEntry

Name

ZipEntry

Synopsis

Class Name:

java.util.zip.ZipEntry

Superclass:

java.lang.Object

Immediate Subclasses:

None

Interfaces Implemented:

None

Availability:

New as of JDK 1.1

The ZipEntry class represents a single entry in a ZIP file, which is either a compressed file or an uncompressed file. ZipEntry provides methods that set and retrieve various pieces of information about an entry.

When you are reading a ZIP file, you use ZipInputStream.getNextEntry() to return the next entry in the file. Then you can retrieve information about that particular entry. You can also read the entries in a ZIP file in a nonsequential order using the ZipFile class.

When you are writing a ZIP file, you use ZipOutputStream.putNextEntry() to write an entry, and you must create your own ZipEntry objects. If you are storing compressed (deflated) files, you need only specify a name for the ZipEntry ; the other fields are filled in automatically. If, however, you are placing uncompressed entries, you need to specify the size of each entry and provide a CRC-32 checksum value.

Class Summary

public class java.util.zip.ZipEntry extends java.lang.Object {
  // Constants
  public static final int DEFLATED;
  public static final int STORED;
  // Constructors
  public ZipEntry(String name);
  // Instance Methods
  public String getComment();
  public long getCompressedSize();
  public long getCrc();
  public byte[] getExtra();
  public int getMethod();
  public String getName();
  public long getSize();
  public long getTime();
  public boolean isDirectory();
  public void setComment(String comment);
  public void setCrc(long crc);
  public void setExtra(byte[] extra);
  public void setMethod(int method);
  public void setSize(long size);
  public void setTime(long time);
  public String toString();
}

Constants

DEFLATED

public static final int DEFLATED

Description: A constant that represents an entry that is stored using the deflate algorithm.

STORED

public static final int STORED

Description: A constant that represents an entry that is stored verbatim; in other words, with no compression applied.

Constructors

ZipEntry

public ZipEntry(String name)

Parameters

name: The name of the entry.

Throws

NullPointerException

If name is null.

IllegalArgumentException

If name is longer than 0xFFFF bytes.

Description

This constructor creates a ZipEntry with the given name.

Instance Methods

getComment

public String getComment()

Returns

The comment of this entry or null if one has not been specified.

Description

This method returns the comment string for this ZipEntry.

getCompressedSize

public long getCompressedSize()

Returns

The compressed size of this entry or -1 is the compressed size is not known.

Description

This method returns the compressed size of this ZipEntry.

getCrc

public long getCrc()

Returns

The checksum value for this entry.

Description

This method returns the CRC-32 checksum value for this ZipEntry.

getExtra

public byte[] getExtra()

Returns

The extra field data for this entry or null if there is none.

Description

This method returns the bytes in the extra field data for this ZipEntry.

getMethod

public int getMethod()

Returns

The compression method of this entry or -1 if it has not been specified.

Description

This method returns the compression method of this ZipEntry. Valid values are DEFLATED and STORED.

getName

public String getName()

Returns

The name of this entry.

Description

This method returns the string name of this ZipEntry.

getSize

public long getSize()

Returns

The uncompressed size of this entry or -1 if the uncompressed size is not known.

Description

This method returns the uncompressed size of this ZipEntry.

getTime

public long getTime()

Returns

The modification date of this entry.

Description

This method returns the modification date of this ZipEntry as the number of milliseconds since midnight, January 1, 1970 GMT.

isDirectory

public boolean isDirectory()

Returns

A boolean value that indicates whether or not this entry is a directory.

Description

This method returns true if this ZipEntry represents a directory.

setComment

public void setComment(String comment)

Parameters

comment: The new comment string.

Throws

IllegalArgumentException: If comment is longer than 0xFFFF bytes.

Description

This method sets the comment string of this ZipEntry.

setCrc

public void setCrc(long crc)

Parameters

crc: The new checksum value.

Description

This method sets the CRC-32 checksum value for this ZipEntry.

setExtra

public void setExtra(byte[] extra)

Parameters

extra: The extra field data.

Throws

IllegalArgumentException: If extra is longer than 0xFFFF bytes.

Description

This method sets the extra field data for this ZipEntry.

setMethod

public void setMethod(int method)

Parameters

method: The new compression method.

Throws

IllegalArgumentException: If method is not DEFLATED or STORED.

Description

This method sets the compression method of this ZipEntry. This corresponds to the compression level of Deflater.

setSize

public void setSize(long size)

Parameters

size: The new uncompressed entry size.

Throws

IllegalArgumentException: If size is less than 0 or greater than 0xFFFFFFFF bytes.

Description

This method sets the uncompressed size of this ZipEntry.

setTime

public void setTime(long time)

Parameters

time: The new modification date, expressed as the number of seconds since midnight, January 1, 1970 GMT.

Description

This method sets the modification date of this ZipEntry.

toString

public String toString()

Returns

A string representation of this object.

Overrides

Object.toString()

Description

This method returns the name of this ZipEntry.

Inherited Methods

Method	Inherited From	Method	Inherited From
`clone()`	`Object`	`equals(Object)`	`Object`
`finalize()`	`Object`	`getClass()`	`Object`
`hashCode()`	`Object`	`notify()`	`Object`
`notifyAll()`	`Object`	`wait()`	`Object`
`wait(long)`	`Object`	`wait(long, int)`	`Object`