ZipEntry B4X (B4A / B4J) Reference Documentation

ChilkatZipEntry

Current Version: 11.6.0

Chilkat.ZipEntry

Inspect, extract, update, and iterate individual entries inside a ZIP archive.

Chilkat.ZipEntry represents a single item associated with a Chilkat.Zip archive. An entry may be a file already stored in an opened ZIP, a referenced filesystem file waiting to be compressed, an in-memory text or binary entry, or a directory entry. It provides access to entry-level metadata, compressed and uncompressed data, timestamps, attributes, CRC values, encryption information, and extraction or replacement operations for that specific ZIP item.

Entry metadata

Inspect filenames, stored ZIP paths, comments, timestamps, CRC values, attributes, sizes, compression method, and compression level.

Entry type and state

Use EntryType to understand whether the entry comes from an existing ZIP, a filesystem reference, memory data, or a directory.

Extract one entry

Extract a selected file entry to disk, inflate its contents into memory, or read the uncompressed data into Chilkat objects.

Read compressed data

Access the raw compressed entry data when an application needs ZIP-level control rather than only the inflated contents.

Replace or append data

Update an entry's contents from strings, byte data, files, or in-memory data sources before writing the ZIP archive.

Iterate archive entries

Walk through entries returned from Chilkat.Zip methods to inspect, filter, extract, or modify ZIP contents one item at a time.

Common pattern: Open or create a Chilkat.Zip object, obtain a ZipEntry using methods such as EntryAt, EntryOf, EntryMatching, or FirstEntry, then inspect metadata, extract contents, update the entry, or continue iterating through the archive. Use Chilkat.Zip for whole-archive operations and ZipEntry for operations on one specific archive item.

Declare / Initialize / Dispose

Sub Process_Globals
    Private obj As ChilkatZipEntry
End Sub

' Call Initialize before first use -- typically in AppStart (B4J)
' or Activity_Create (B4A):
obj.Initialize                ' classes without events
obj.Initialize("evt")        ' classes with events: "evt" becomes the
                              ' prefix of event Subs such as evt_PercentDone
Initialize  /  Initialize (EventName As String)

Creates the underlying native Chilkat object. Classes that support events take an EventName argument: it becomes the prefix of the event Subs (<EventName>_AbortCheck, <EventName>_PercentDone, <EventName>_ProgressInfo); classes without events take no arguments. The native Chilkat library loads automatically on the first Initialize — from the APK on Android, or extracted from ChilkatB4J.jar on Windows/Linux/macOS.

IsInitialized As Boolean

True if Initialize has been called and the native object exists.

Dispose

Explicitly frees the underlying native object. Calling Dispose is optional — every ChilkatZipEntry is also freed automatically when garbage-collected — but is recommended for long-lived objects holding sockets, sessions, or large buffers. A disposed object can be re-Initialized.

Properties

Comment
' read/write
Comment As String

Gets or sets the comment stored in the ZIP archive for this entry.

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CompressedLength
' read-only
CompressedLength As Long

The compressed size of this entry, in bytes.

For mapped entries (entries already contained within an opened ZIP archive), this property contains the actual compressed size stored within the ZIP.

For file entries or data entries that have not yet been written to a ZIP archive, compression has not yet occurred. In these cases, this property contains:

  • The current uncompressed data size for data entries.
  • The cached filesystem file size for referenced file entries.

After the ZIP archive is written, the entries become mapped entries, and this property then reflects the actual compressed size stored in the ZIP archive.

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CompressedLength64
' read-only
CompressedLength64 As Long

The compressed size of this entry, in bytes, as a 64-bit integer.

For mapped entries (entries already contained within an opened ZIP archive), this property contains the actual compressed size stored within the ZIP.

For file entries or data entries that have not yet been written to a ZIP archive, compression has not yet occurred. In these cases, this property contains:

  • The current uncompressed data size for data entries.
  • The cached filesystem file size for referenced file entries.

After the ZIP archive is written, the entries become mapped entries, and this property then reflects the actual compressed size stored in the ZIP archive.

Use this property when sizes may exceed the range of a 32-bit integer.

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CompressedLengthStr
' read-only
CompressedLengthStr As String

The compressed size of this entry as a decimal string.

For mapped entries (entries already contained within an opened ZIP archive), this property contains the actual compressed size stored within the ZIP.

For file entries or data entries that have not yet been written to a ZIP archive, compression has not yet occurred. In these cases, this property contains:

  • The current uncompressed data size for data entries.
  • The cached filesystem file size for referenced file entries.

After the ZIP archive is written, the entries become mapped entries, and this property then reflects the actual compressed size stored in the ZIP archive.

This property is useful when sizes may exceed the range of a 32-bit integer.

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CompressionLevel
' read/write
CompressionLevel As Int

Gets or sets the compression level for this entry.

A value of 0 means no compression, and a value of 9 means maximum compression.

The default value is 6.

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CompressionMethod
' read/write
CompressionMethod As Int

Gets or sets the compression method used for this entry.

  • 0 means no compression.
  • 8 means Deflate compression.

Deflate is the standard compression algorithm used by common ZIP utilities such as WinZip.

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Crc
' read-only
Crc As Int

The CRC value for this ZIP entry.

For AES-encrypted entries, the CRC value is 0.

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DebugLogFilePath
' read/write
DebugLogFilePath As String

If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.

Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.

Possible causes of hangs include:

  • A timeout property set to 0, indicating an infinite timeout.
  • A hang occurring within an event callback in the application code.
  • An internal bug in the Chilkat code causing the hang.

More Information and Examples
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EncryptionKeyLen
' read-only
EncryptionKeyLen As Int
Introduced in version 9.5.0.69

The AES encryption key length for this entry.

If this entry is AES encrypted, the value is 128, 192, or 256.

If this entry is not AES encrypted, the value is 0.

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EntryID
' read-only
EntryID As Int

A unique identifier assigned to this entry while the ZIP object is instantiated in memory.

This ID can be used to retrieve the same entry later with Zip.EntryById.

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EntryType
' read-only
EntryType As Int

Indicates the origin and current state of this ZIP entry.

  • 0 — Mapped Entry: an entry that already exists in an open ZIP file.
  • 1 — File Entry: a file in the local filesystem that has been referenced, but not yet read or compressed.
  • 2 — Data Entry: an entry containing uncompressed data already held in memory.
  • 3 — Null Entry: an entry that no longer exists in the ZIP archive.
  • 4 — New Directory Entry: a directory entry added to the ZIP object.

When the ZIP archive is written by calling WriteZip or WriteToMemory, entries are transformed into mapped entries. In other words, after writing, they point to compressed data contained in the newly created or rewritten ZIP archive.

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FileDateTimeStr
' read/write
FileDateTimeStr As String

Gets or sets the local last-modified date/time for this ZIP entry in RFC 822 string format.

Example RFC 822 date/time strings:

Tue, 15 Nov 1994 12:45:26 GMT
Fri, 05 Jan 2024 18:30:00 -0500

The timezone may be specified either as a named timezone such as GMT, or as a numeric UTC offset such as -0500.

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FileName
' read/write
FileName As String

Gets or sets the filename, including any relative path, stored for this entry inside the ZIP archive.

Changing this property changes the path/name that will appear in the ZIP archive. It does not rename a source file in the local filesystem.

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FileNameHex
' read-only
FileNameHex As String

Returns the raw filename bytes found in the ZIP entry, encoded as a hexadecimal string.

This can be useful for diagnosing filename encoding issues.

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HeartbeatMs
' read/write
HeartbeatMs As Int

The interval in milliseconds between each AbortCheck event callback, which enables an application to abort certain method calls before they complete. By default, HeartbeatMs is set to 0, meaning no AbortCheck event callbacks will trigger.

More Information and Examples
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IsAesEncrypted
' read-only
IsAesEncrypted As Boolean
Introduced in version 9.5.0.69

Indicates whether this ZIP entry is AES encrypted.

This property can be True only for entries already contained in a ZIP archive, such as entries obtained after calling OpenZip, OpenBd, or OpenFromMemory.

If the entry is not AES encrypted, the property is False.

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IsDirectory
' read-only
IsDirectory As Boolean

Indicates whether this ZIP entry is a directory entry.

The value is True if the entry represents a directory, and False if it represents a file.

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LastErrorHtml
' read-only
LastErrorHtml As String

Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastErrorText
' read-only
LastErrorText As String

Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastErrorXml
' read-only
LastErrorXml As String

Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastMethodSuccess
' read/write
LastMethodSuccess As Boolean

Indicates the success or failure of the most recent method call: True means success, False means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages. Note: This property does not apply to methods that return integer values or to boolean-returning methods where the boolean does not indicate success or failure.

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TextFlag
' read/write
TextFlag As Boolean

Gets or sets the text flag in the internal file attributes for this ZIP entry.

This flag indicates whether the entry contents should be considered text rather than binary data.

The flag is informational and does not need to be accurate for normal ZIP processing. It is provided for compatibility with applications that may be sensitive to this attribute.

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UncompressedLength
' read-only
UncompressedLength As Long

The uncompressed size of this entry, in bytes.

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UncompressedLength64
' read-only
UncompressedLength64 As Long

The uncompressed size of this entry, in bytes, as a 64-bit integer.

Use this property when the uncompressed size may exceed the range of a 32-bit integer.

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UncompressedLengthStr
' read-only
UncompressedLengthStr As String

The uncompressed size of this ZIP entry as a decimal string.

This is useful when the uncompressed size may be larger than what can safely be represented by a 32-bit integer.

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VerboseLogging
' read/write
VerboseLogging As Boolean

If set to True, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is False. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

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Version
' read-only
Version As String

Version of the component/library, such as "10.1.0"

More Information and Examples
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Methods

AppendString
AppendString (strContent As String, charset As String) As Boolean

Appends text data to this ZIP entry's file contents.

The text is converted to bytes using the character encoding specified by charset, such as utf-8, utf-16, or ansi.

If this entry is already a Data Entry (EntryType = 2), then the encoded bytes are appended directly to the existing uncompressed in-memory data.

If this entry is not already a Data Entry, then the entry is first converted into a Data Entry before the new text data is appended.

  • If the entry is a mapped entry (EntryType = 0), the compressed ZIP entry data is first inflated into memory. The new text data is then appended, and the entry becomes a Data Entry containing the combined uncompressed data.
  • If the entry is a file entry (EntryType = 1), the referenced filesystem file is first loaded into memory. The new text data is then appended, and the entry becomes a Data Entry containing the combined data.

After this method is called, the entry contents exist entirely as uncompressed in-memory data associated with the ZipEntry object.

Returns True for success, False for failure.

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CopyToBase64
CopyToBase64 As String

Returns the compressed data for this ZIP entry as a Base64-encoded string.

This method can only be used when the entry already contains compressed data, meaning the entry is a mapped entry.

This is possible for entries from a ZIP archive that has already been opened, or after writing a ZIP archive while it remains open.

Returns Null on failure

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CopyToHex
CopyToHex As String

Returns the compressed data for this ZIP entry as a hexadecimal encoded string.

This method can only be used when the entry already contains compressed data, meaning the entry is a mapped entry.

This is possible for entries from a ZIP archive that has already been opened, or after writing a ZIP archive while it remains open.

Returns Null on failure

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Extract
Extract (dirPath As String) As Boolean

Extracts this ZIP entry beneath the specified base directory.

The entry is extracted according to the relative path stored in the ZIP archive.

For example, if the entry filename is docs/readme.txt and dirPath is c:/temp/output, the file is extracted to c:/temp/output/docs/readme.txt.

Use ExtractInto instead if the file should be extracted directly into a specific directory regardless of the path stored in the ZIP archive.

Returns True for success, False for failure.

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ExtractInto
ExtractInto (dirPath As String) As Boolean

Extracts this entry directly into the specified directory, ignoring any path information stored in the ZIP entry.

For example, if the entry filename is docs/readme.txt and dirPath is c:/temp/output, the file is extracted to c:/temp/output/readme.txt.

If this entry is a directory entry, nothing is extracted. To create the directory represented by a directory entry, use Extract instead.

Returns True for success, False for failure.

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GetNext
GetNext As Boolean
Introduced in version 11.0.0

Updates this ZipEntry object so that it represents the next entry in the same ZIP archive.

The next entry may be either a file entry or a directory entry.

Returns True if the object was advanced to the next entry. Returns False if there are no more entries.

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GetNextMatch
GetNextMatch (pattern As String) As Boolean
Introduced in version 11.0.0

Updates this ZipEntry object so that it represents the next entry in the ZIP archive matching the specified wildcard pattern.

The wildcard character * matches zero or more characters. Matching is performed against the full stored filename, including any relative path.

The matching entry may be either a file entry or a directory entry.

Returns True if a matching entry is found. Returns False if no further matching entry exists.

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ReplaceString
ReplaceString (strContent As String, charset As String) As Boolean

Replaces this ZIP entry's existing contents with new text data.

The text is converted to bytes using the character encoding specified by charset, such as utf-8 or ansi.

The resulting bytes become the complete contents of the entry.

Returns True for success, False for failure.

More Information and Examples
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SetDt
SetDt (dt As ChilkatDateTime)

Sets the last-modified date/time for this ZIP entry.

The dt argument is a CkDateTime object containing the date/time to store for the entry.

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UnzipToBd
UnzipToBd (binData As ChilkatBinData) As Boolean
Introduced in version 9.5.0.67

Unzips this entry directly into a BinData object.

The uncompressed bytes are written to binData.

Returns True for success, False for failure.

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UnzipToSb
UnzipToSb (lineEndingBehavior As Int, srcCharset As String, sb As ChilkatStringBuilder) As Boolean
Introduced in version 9.5.0.67

Unzips this entry as text and appends the result to a StringBuilder.

The srcCharset argument specifies how the uncompressed bytes should be interpreted, such as utf-8, utf-16, or windows-1252.

The lineEndingBehavior argument controls line-ending conversion:

  • 0 — leave line endings unchanged.
  • 1 — convert all line endings to bare LF.
  • 2 — convert all line endings to CRLF.

Returns True for success, False for failure.

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UnzipToStream
UnzipToStream (toStream As ChilkatStream) As Boolean
Introduced in version 9.5.0.67

Unzips this entry to a stream.

If called synchronously, the toStream must have a sink, such as a file or another stream object.

If called asynchronously, the foreground thread can read from the stream while the unzip operation writes to it.

Returns True for success, False for failure.

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UnzipToString
UnzipToString (lineEndingBehavior As Int, srcCharset As String) As String

Inflates this entry and returns the uncompressed data as a string.

The srcCharset argument specifies how the uncompressed bytes should be interpreted, such as utf-8, utf-16, or windows-1252.

The lineEndingBehavior argument controls line-ending conversion:

  • 0 — leave line endings unchanged.
  • 1 — convert all line endings to bare LF.
  • 2 — convert all line endings to CRLF.

Returns Null on failure

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Events

All Chilkat methods are synchronous: the call returns when the work is done. During a call, ChilkatZipEntry raises three events so your application can show progress and offer a way out. The event-name prefix is the string passed to Initialize:

entry.Initialize("evt")     ' event Subs are named evt_AbortCheck, evt_PercentDone, evt_ProgressInfo
entry.HeartbeatMs = 250     ' raise evt_AbortCheck 4 times per second during Chilkat calls

AbortCheck fires at regular intervals controlled by the HeartbeatMs property (0, the default, disables it); PercentDone fires when an operation's completion percentage is known; ProgressInfo delivers named progress values. Returning True from an AbortCheck or PercentDone Sub aborts the running method. Implement only the Subs you need — events are skipped entirely when no matching Sub exists.

If a Chilkat call runs on a separate thread (e.g. via the Threading library), its events are automatically queued to the main thread. Events raised that way cannot abort by return value; set the object's AbortCurrent property to True instead.

AbortCheck
' evt = the EventName passed to Initialize
' Return True to abort the Chilkat method in progress.
Sub evt_AbortCheck As Boolean

Enables a method call to be aborted by triggering the AbortCheck event at intervals defined by the HeartbeatMs property. If HeartbeatMs is set to its default value of 0, no events will occur. For instance, set HeartbeatMs to 200 to trigger 5 AbortCheck events per second.

More Information and Examples

Example (object initialized with entry.Initialize("evt")):

entry.HeartbeatMs = 250   ' fire evt_AbortCheck 4 times per second

Sub evt_AbortCheck As Boolean
    ' Called every HeartbeatMs milliseconds while a Chilkat method is running.
    Return False   ' Return True to abort the method in progress
End Sub
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PercentDone
' evt = the EventName passed to Initialize
' Return True to abort the Chilkat method in progress.
Sub evt_PercentDone (PctDone As Int) As Boolean

This provides the percentage completion for any method involving network communications or time-consuming processing, assuming the progress can be measured as a percentage. This event is triggered only when it's possible and logical to express the operation's progress as a percentage. The pctDone argument will range from 1 to 100. For methods that finish quickly, the number of PercentDone callbacks may vary, but the final callback will have pctDone equal to 100. For longer operations, callbacks will not exceed one per percentage point (e.g., 1, 2, 3, ..., 98, 99, 100).

The PercentDone callback also acts as an AbortCheck event. For fast methods where PercentDone fires, an AbortCheck event may not trigger since the PercentDone callback already provides an opportunity to abort. For longer operations, where time between PercentDone callbacks is extended, AbortCheck callbacks enable more responsive operation termination.

To abort the operation, set the abort output argument to True. This will cause the method to terminate and return a failure status or corresponding failure value.

More Information and Examples

Example (object initialized with entry.Initialize("evt")):

Sub evt_PercentDone (PctDone As Int) As Boolean
    ' PctDone ranges from 1 to 100.
    Log("Percent done: " & PctDone)
    Return False   ' Return True to abort the method in progress
End Sub
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ProgressInfo
' evt = the EventName passed to Initialize
Sub evt_ProgressInfo (Name As String, Value As String)

This event callback provides tag name/value pairs that detail what occurs during a method call. To discover existing tag names, create code to handle the event, emit the pairs, and review them. Most tag names are self-explanatory.

Note: Some Chilkat methods don't fire any ProgressInfo events.

More Information and Examples

Example (object initialized with entry.Initialize("evt")):

Sub evt_ProgressInfo (Name As String, Value As String)
    Log(Name & ": " & Value)
End Sub
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