ZipInputStream (Java SE 23 & JDK 23)
Description: declaration: module: java.base, package: java.util.zip, class: ZipInputStream
Keywords: java.util.zip.ZipInputStream class

# Class ZipInputStream

java.lang.Object
java.io.InputStream
java.io.FilterInputStream
java.util.zip.InflaterInputStream
java.util.zip.ZipInputStream

All Implemented Interfaces:
  `Closeable`, `AutoCloseable`

Direct Known Subclasses:
  `JarInputStream`

public class ZipInputStream extends InflaterInputStream
An input stream for reading compressed and uncompressed ZIP file entries from a stream of bytes in the ZIP file format.

Unless otherwise noted, passing a `null` argument to a constructor or method in this class will cause a `NullPointerException` to be thrown.

## Reading Zip File Entries

The `getNextEntry()` method is used to read the next ZIP file entry (Local file (LOC) header record in the ZIP format) and position the stream at the entry's file data. The file data may read using one of the `ZipInputStream` read methods such as `read` or `readAllBytes()`. For example:

      Path jar = Path.of("foo.jar");
      try (InputStream is = Files.newInputStream(jar);
           ZipInputStream zis = new ZipInputStream(is)) {
          ZipEntry ze;
          while ((ze = zis.getNextEntry()) != null) {
             var bytes = zis.readAllBytes();
             System.out.printf("Entry: %s, bytes read: %s%n", ze.getName(),
                     bytes.length);
          }
      }

API Note:
  The LOC header contains metadata about the ZIP file entry. `ZipInputStream` does not read the Central directory (CEN) header for the entry and therefore will not have access to its metadata such as the external file attributes. ZipFile may be used when the information stored within the CEN header is required.
Since:
  1.1

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `static final int`
  `CENATT`
  Central directory (CEN) header internal file attributes field offset.
  `static final int`
  `CENATX`
  Central directory (CEN) header external file attributes field offset.
  `static final int`
  `CENCOM`
  Central directory (CEN) header comment length field offset.
  `static final int`
  `CENCRC`
  Central directory (CEN) header uncompressed file crc-32 value field offset.
  `static final int`
  `CENDSK`
  Central directory (CEN) header disk number start field offset.
  `static final int`
  `CENEXT`
  Central directory (CEN) header extra field length field offset.
  `static final int`
  `CENFLG`
  Central directory (CEN) header encrypt, decrypt flags field offset.
  `static final int`
  `CENHDR`
  Central directory (CEN) header size in bytes (including signature).
  `static final int`
  `CENHOW`
  Central directory (CEN) header compression method field offset.
  `static final int`
  `CENLEN`
  Central directory (CEN) header uncompressed size field offset.
  `static final int`
  `CENNAM`
  Central directory (CEN) header filename length field offset.
  `static final int`
  `CENOFF`
  Central directory (CEN) header LOC header offset field offset.
  `static final long`
  `CENSIG`
  Central directory (CEN) header signature.
  `static final int`
  `CENSIZ`
  Central directory (CEN) header compressed size field offset.
  `static final int`
  `CENTIM`
  Central directory (CEN) header modification time field offset.
  `static final int`
  `CENVEM`
  Central directory (CEN) header version made by field offset.
  `static final int`
  `CENVER`
  Central directory (CEN) header version needed to extract field offset.
  `static final int`
  `ENDCOM`
  End of central directory (END) header ZIP file comment length field offset.
  `static final int`
  `ENDHDR`
  End of central directory (END) header size in bytes (including signature).
  `static final int`
  `ENDOFF`
  End of central directory (END) header offset for the first CEN header field offset.
  `static final long`
  `ENDSIG`
  End of central directory (END) header signature.
  `static final int`
  `ENDSIZ`
  End of central directory (END) header central directory size in bytes field offset.
  `static final int`
  `ENDSUB`
  End of central directory (END) header number of entries on this disk field offset.
  `static final int`
  `ENDTOT`
  End of central directory (END) header total number of entries field offset.
  `static final int`
  `EXTCRC`
  Extra local (EXT) header uncompressed file crc-32 value field offset.
  `static final int`
  `EXTHDR`
  Extra local (EXT) header size in bytes (including signature).
  `static final int`
  `EXTLEN`
  Extra local (EXT) header uncompressed size field offset.
  `static final long`
  `EXTSIG`
  Extra local (EXT) header signature.
  `static final int`
  `EXTSIZ`
  Extra local (EXT) header compressed size field offset.
  `static final int`
  `LOCCRC`
  Local file (LOC) header uncompressed file crc-32 value field offset.
  `static final int`
  `LOCEXT`
  Local file (LOC) header extra field length field offset.
  `static final int`
  `LOCFLG`
  Local file (LOC) header general purpose bit flag field offset.
  `static final int`
  `LOCHDR`
  Local file (LOC) header size in bytes (including signature).
  `static final int`
  `LOCHOW`
  Local file (LOC) header compression method field offset.
  `static final int`
  `LOCLEN`
  Local file (LOC) header uncompressed size field offset.
  `static final int`
  `LOCNAM`
  Local file (LOC) header filename length field offset.
  `static final long`
  `LOCSIG`
  Local file (LOC) header signature.
  `static final int`
  `LOCSIZ`
  Local file (LOC) header compressed size field offset.
  `static final int`
  `LOCTIM`
  Local file (LOC) header modification time field offset.
  `static final int`
  `LOCVER`
  Local file (LOC) header version needed to extract field offset.

  ### Fields declared in class java.util.zip.InflaterInputStream

  `buf, inf, len`

  ### Fields declared in class java.io.FilterInputStream

  `in`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `ZipInputStream(InputStream in)`
  Creates a new ZIP input stream.
  `ZipInputStream(InputStream in, Charset charset)`
  Creates a new ZIP input stream.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `int`
  `available()`
  Returns 0 when end of stream is detected for the current ZIP entry or `closeEntry()` has been called on the current ZIP entry, otherwise returns 1.
  `void`
  `close()`
  Closes this input stream and releases any system resources associated with the stream.
  `void`
  `closeEntry()`
  Closes the current ZIP entry and positions the stream for reading the next entry.
  `protected ZipEntry`
  `createZipEntry(String name)`
  Creates a new `ZipEntry` object for the specified entry name.
  `ZipEntry`
  `getNextEntry()`
  Reads the next ZIP file entry and positions the stream at the beginning of the entry data.
  `int`
  `read()`
  Reads the next byte of data from the input stream for the current ZIP entry.
  `int`
  `read(byte[] b, int off, int len)`
  Reads the requested number of bytes from the input stream into the given byte array for the current ZIP entry returning the number of inflated bytes.
  `byte[]`
  `readAllBytes()`
  Reads all remaining bytes from the input stream for the current ZIP entry.
  `int`
  `readNBytes(byte[] b, int off, int len)`
  Reads the requested number of bytes from the input stream into the given byte array for the current ZIP entry returning the number of inflated bytes.
  `byte[]`
  `readNBytes(int len)`
  Reads up to a specified number of bytes from the input stream for the current ZIP entry.
  `long`
  `skip(long n)`
  Skips over and discards `n` bytes of data from this input stream for the current ZIP entry.
  `void`
  `skipNBytes(long n)`
  Skips over and discards exactly `n` bytes of data from this input stream for the current ZIP entry.
  `long`
  `transferTo(OutputStream out)`
  Reads all bytes from this input stream for the current ZIP entry and writes the bytes to the given output stream in the order that they are read.

  ### Methods declared in class java.util.zip.InflaterInputStream

  `fill, mark, markSupported, reset`

  ### Methods declared in class java.io.FilterInputStream

  `read`

  ### Methods declared in class java.io.InputStream

  `nullInputStream`

  ### Methods declared in class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Field Details

  - ### LOCSIG

    static final long LOCSIG
    Local file (LOC) header signature.
    See Also:
      - Constant Field Values

  - ### EXTSIG

    static final long EXTSIG
    Extra local (EXT) header signature.
    See Also:
      - Constant Field Values

  - ### CENSIG

    static final long CENSIG
    Central directory (CEN) header signature.
    See Also:
      - Constant Field Values

  - ### ENDSIG

    static final long ENDSIG
    End of central directory (END) header signature.
    See Also:
      - Constant Field Values

  - ### LOCHDR

    static final int LOCHDR
    Local file (LOC) header size in bytes (including signature).
    See Also:
      - Constant Field Values

  - ### EXTHDR

    static final int EXTHDR
    Extra local (EXT) header size in bytes (including signature).
    See Also:
      - Constant Field Values

  - ### CENHDR

    static final int CENHDR
    Central directory (CEN) header size in bytes (including signature).
    See Also:
      - Constant Field Values

  - ### ENDHDR

    static final int ENDHDR
    End of central directory (END) header size in bytes (including signature).
    See Also:
      - Constant Field Values

  - ### LOCVER

    static final int LOCVER
    Local file (LOC) header version needed to extract field offset.
    See Also:
      - Constant Field Values

  - ### LOCFLG

    static final int LOCFLG
    Local file (LOC) header general purpose bit flag field offset.
    See Also:
      - Constant Field Values

  - ### LOCHOW

    static final int LOCHOW
    Local file (LOC) header compression method field offset.
    See Also:
      - Constant Field Values

  - ### LOCTIM

    static final int LOCTIM
    Local file (LOC) header modification time field offset.
    See Also:
      - Constant Field Values

  - ### LOCCRC

    static final int LOCCRC
    Local file (LOC) header uncompressed file crc-32 value field offset.
    See Also:
      - Constant Field Values

  - ### LOCSIZ

    static final int LOCSIZ
    Local file (LOC) header compressed size field offset.
    See Also:
      - Constant Field Values

  - ### LOCLEN

    static final int LOCLEN
    Local file (LOC) header uncompressed size field offset.
    See Also:
      - Constant Field Values

  - ### LOCNAM

    static final int LOCNAM
    Local file (LOC) header filename length field offset.
    See Also:
      - Constant Field Values

  - ### LOCEXT

    static final int LOCEXT
    Local file (LOC) header extra field length field offset.
    See Also:
      - Constant Field Values

  - ### EXTCRC

    static final int EXTCRC
    Extra local (EXT) header uncompressed file crc-32 value field offset.
    See Also:
      - Constant Field Values

  - ### EXTSIZ

    static final int EXTSIZ
    Extra local (EXT) header compressed size field offset.
    See Also:
      - Constant Field Values

  - ### EXTLEN

    static final int EXTLEN
    Extra local (EXT) header uncompressed size field offset.
    See Also:
      - Constant Field Values

  - ### CENVEM

    static final int CENVEM
    Central directory (CEN) header version made by field offset.
    See Also:
      - Constant Field Values

  - ### CENVER

    static final int CENVER
    Central directory (CEN) header version needed to extract field offset.
    See Also:
      - Constant Field Values

  - ### CENFLG

    static final int CENFLG
    Central directory (CEN) header encrypt, decrypt flags field offset.
    See Also:
      - Constant Field Values

  - ### CENHOW

    static final int CENHOW
    Central directory (CEN) header compression method field offset.
    See Also:
      - Constant Field Values

  - ### CENTIM

    static final int CENTIM
    Central directory (CEN) header modification time field offset.
    See Also:
      - Constant Field Values

  - ### CENCRC

    static final int CENCRC
    Central directory (CEN) header uncompressed file crc-32 value field offset.
    See Also:
      - Constant Field Values

  - ### CENSIZ

    static final int CENSIZ
    Central directory (CEN) header compressed size field offset.
    See Also:
      - Constant Field Values

  - ### CENLEN

    static final int CENLEN
    Central directory (CEN) header uncompressed size field offset.
    See Also:
      - Constant Field Values

  - ### CENNAM

    static final int CENNAM
    Central directory (CEN) header filename length field offset.
    See Also:
      - Constant Field Values

  - ### CENEXT

    static final int CENEXT
    Central directory (CEN) header extra field length field offset.
    See Also:
      - Constant Field Values

  - ### CENCOM

    static final int CENCOM
    Central directory (CEN) header comment length field offset.
    See Also:
      - Constant Field Values

  - ### CENDSK

    static final int CENDSK
    Central directory (CEN) header disk number start field offset.
    See Also:
      - Constant Field Values

  - ### CENATT

    static final int CENATT
    Central directory (CEN) header internal file attributes field offset.
    See Also:
      - Constant Field Values

  - ### CENATX

    static final int CENATX
    Central directory (CEN) header external file attributes field offset.
    See Also:
      - Constant Field Values

  - ### CENOFF

    static final int CENOFF
    Central directory (CEN) header LOC header offset field offset.
    See Also:
      - Constant Field Values

  - ### ENDSUB

    static final int ENDSUB
    End of central directory (END) header number of entries on this disk field offset.
    See Also:
      - Constant Field Values

  - ### ENDTOT

    static final int ENDTOT
    End of central directory (END) header total number of entries field offset.
    See Also:
      - Constant Field Values

  - ### ENDSIZ

    static final int ENDSIZ
    End of central directory (END) header central directory size in bytes field offset.
    See Also:
      - Constant Field Values

  - ### ENDOFF

    static final int ENDOFF
    End of central directory (END) header offset for the first CEN header field offset.
    See Also:
      - Constant Field Values

  - ### ENDCOM

    static final int ENDCOM
    End of central directory (END) header ZIP file comment length field offset.
    See Also:
      - Constant Field Values

- ## Constructor Details

  - ### ZipInputStream

    public ZipInputStream(InputStream in)
    Creates a new ZIP input stream.

    The UTF-8 `charset` is used to decode the entry names.

    Parameters:
      `in` - the actual input stream

  - ### ZipInputStream

    public ZipInputStream(InputStream in, Charset charset)
    Creates a new ZIP input stream.
    Parameters:
      `in` - the actual input stream
      `charset` - The charset to be used to decode the ZIP entry name (ignored if the language encoding bit of the ZIP entry's general purpose bit flag is set).
    Since:
      1.7

- ## Method Details

  - ### getNextEntry

    public ZipEntry getNextEntry() throws IOException
    Reads the next ZIP file entry and positions the stream at the beginning of the entry data.
    Returns:
      the next ZIP file entry, or null if there are no more entries
    Throws:
      `ZipException` - if a ZIP file error has occurred
      `IOException` - if an I/O error has occurred

  - ### closeEntry

    public void closeEntry() throws IOException
    Closes the current ZIP entry and positions the stream for reading the next entry.
    Throws:
      `ZipException` - if a ZIP file error has occurred
      `IOException` - if an I/O error has occurred

  - ### available

    public int available() throws IOException
    Returns 0 when end of stream is detected for the current ZIP entry or `closeEntry()` has been called on the current ZIP entry, otherwise returns 1.

    Programs should not count on this method to return the actual number of bytes that could be read without blocking.

    Overrides:
      `available` in class `InflaterInputStream`
    Returns:
      0 when end of stream is detected for the current ZIP entry or `closeEntry()` has been called on the current ZIP entry, otherwise 1.
    Throws:
      `IOException` - if an I/O error occurs.

  - ### read

    public int read() throws IOException
    Reads the next byte of data from the input stream for the current ZIP entry. This method will block until enough input is available for decompression.
    Overrides:
      `read` in class `InflaterInputStream`
    Returns:
      the byte read, or -1 if the end of the stream is reached
    Throws:
      `IOException` - if an I/O error has occurred
    See Also:
      - `FilterInputStream.in`

  - ### readAllBytes

    public byte[] readAllBytes() throws IOException
    Reads all remaining bytes from the input stream for the current ZIP entry. This method blocks until all remaining bytes have been read and end of stream is detected, or an exception is thrown. This method does not close the input stream.

    When this stream reaches end of stream, further invocations of this method will return an empty byte array.

    Note that this method is intended for simple cases where it is convenient to read all bytes into a byte array. It is not intended for reading input streams with large amounts of data.

    If an I/O error occurs reading from the input stream, then it may do so after some, but not all, bytes have been read. Consequently, the input stream may not be at end of stream and may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs.

    Overrides:
      `readAllBytes` in class `InputStream`
    Returns:
      a byte array containing the bytes read from this input stream
    Throws:
      `OutOfMemoryError` - if an array of the required size cannot be allocated.
      `IOException` - if an I/O error occurs
    Since:
      9

  - ### readNBytes

    public byte[] readNBytes(int len) throws IOException
    Reads up to a specified number of bytes from the input stream for the current ZIP entry. This method blocks until the requested number of bytes has been read, end of stream is detected, or an exception is thrown. This method does not close the input stream.

    The length of the returned array equals the number of bytes read from the stream. If `len` is zero, then no bytes are read and an empty byte array is returned. Otherwise, up to `len` bytes are read from the stream. Fewer than `len` bytes may be read if end of stream is encountered.

    When this stream reaches end of stream, further invocations of this method will return an empty byte array.

    Note that this method is intended for simple cases where it is convenient to read the specified number of bytes into a byte array. The total amount of memory allocated by this method is proportional to the number of bytes read from the stream which is bounded by `len`. Therefore, the method may be safely called with very large values of `len` provided sufficient memory is available.

    If an I/O error occurs reading from the input stream, then it may do so after some, but not all, bytes have been read. Consequently, the input stream may not be at end of stream and may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs.

    Overrides:
      `readNBytes` in class `InputStream`
    Implementation Note:
      This method calls `super.readNBytes(int len)`.
    Parameters:
      `len` - the maximum number of bytes to read
    Returns:
      a byte array containing the bytes read from this input stream
    Throws:
      `OutOfMemoryError` - if an array of the required size cannot be allocated.
      `IOException` - if an I/O error occurs
    Since:
      11

  - ### readNBytes

    public int readNBytes(byte[] b, int off, int len) throws IOException
    Reads the requested number of bytes from the input stream into the given byte array for the current ZIP entry returning the number of inflated bytes. This method blocks until `len` bytes of input data have been read, end of stream is detected, or an exception is thrown. The number of bytes actually read, possibly zero, is returned. This method does not close the input stream.

    In the case where end of stream is reached before `len` bytes have been read, then the actual number of bytes read will be returned. When this stream reaches end of stream, further invocations of this method will return zero.

    If `len` is zero, then no bytes are read and `0` is returned; otherwise, there is an attempt to read up to `len` bytes.

    The first byte read is stored into element `b[off]`, the next one in to `b[off+1]`, and so on. The number of bytes read is, at most, equal to `len`. Let k be the number of bytes actually read; these bytes will be stored in elements `b[off]` through `b[off+`k`-1]`, leaving elements `b[off+`k `]` through `b[off+len-1]` unaffected.

    If an I/O error occurs reading from the input stream, then it may do so after some, but not all, bytes of `b` have been updated with data from the input stream. Consequently, the input stream and `b` may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs.

    Overrides:
      `readNBytes` in class `InputStream`
    Parameters:
      `b` - the byte array into which the data is read
      `off` - the start offset in `b` at which the data is written
      `len` - the maximum number of bytes to read
    Returns:
      the actual number of bytes read into the buffer
    Throws:
      `IndexOutOfBoundsException` - If `off` is negative, `len` is negative, or `len` is greater than `b.length - off`
      `IOException` - if an I/O error occurs
    Since:
      9

  - ### skipNBytes

    public void skipNBytes(long n) throws IOException
    Skips over and discards exactly `n` bytes of data from this input stream for the current ZIP entry. If `n` is zero, then no bytes are skipped. If `n` is negative, then no bytes are skipped. Subclasses may handle the negative value differently.

    This method blocks until the requested number of bytes has been skipped, end of file is reached, or an exception is thrown.

    If end of stream is reached before the stream is at the desired position, then an `EOFException` is thrown.

    If an I/O error occurs, then the input stream may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs.

    Overrides:
      `skipNBytes` in class `InputStream`
    Parameters:
      `n` - the number of bytes to be skipped.
    Throws:
      `IOException` - if the stream cannot be positioned properly or if an I/O error occurs.
    Since:
      12
    See Also:
      - `InputStream.skip(long)`

  - ### transferTo

    public long transferTo(OutputStream out) throws IOException
    Reads all bytes from this input stream for the current ZIP entry and writes the bytes to the given output stream in the order that they are read. On return, this input stream will be at end of stream. This method does not close either stream.

    This method may block indefinitely reading from the input stream, or writing to the output stream. The behavior for the case where the input and/or output stream is asynchronously closed, or the thread interrupted during the transfer, is highly input and output stream specific, and therefore not specified.

    If the total number of bytes transferred is greater than Long.MAX_VALUE, then `Long.MAX_VALUE` will be returned.

    If an I/O error occurs reading from the input stream or writing to the output stream, then it may do so after some bytes have been read or written. Consequently, the input stream may not be at end of stream and one, or both, streams may be in an inconsistent state. It is strongly recommended that both streams be promptly closed if an I/O error occurs.

    Overrides:
      `transferTo` in class `InputStream`
    Parameters:
      `out` - the output stream, non-null
    Returns:
      the number of bytes transferred
    Throws:
      `IOException` - if an I/O error occurs when reading or writing
    Since:
      9

  - ### read

    public int read(byte[] b, int off, int len) throws IOException
    Reads the requested number of bytes from the input stream into the given byte array for the current ZIP entry returning the number of inflated bytes. If `len` is not zero, the method blocks until some input is available; otherwise, no bytes are read and `0` is returned.

    If the current entry is compressed and this method returns a nonzero integer n then `buf[off]` through `buf[off+`n`-1]` contain the uncompressed data. The content of elements `buf[off+`n`]` through `buf[off+`len`-1]` is undefined, contrary to the specification of the `InputStream` superclass, so an implementation is free to modify these elements during the inflate operation. If this method returns `-1` or throws an exception then the content of `buf[off]` through `buf[off+`len`-1]` is undefined.

    Overrides:
      `read` in class `InflaterInputStream`
    Parameters:
      `b` - the buffer into which the data is read
      `off` - the start offset in the destination array `b`
      `len` - the maximum number of bytes read
    Returns:
      the actual number of bytes read, or -1 if the end of the entry is reached
    Throws:
      `IndexOutOfBoundsException` - if `off` is negative, `len` is negative, or `len` is greater than `b.length - off`
      `ZipException` - if a ZIP file error has occurred
      `IOException` - if an I/O error has occurred
    See Also:
      - `FilterInputStream.in`

  - ### skip

    public long skip(long n) throws IOException
    Skips over and discards `n` bytes of data from this input stream for the current ZIP entry.
    Overrides:
      `skip` in class `InflaterInputStream`
    Parameters:
      `n` - the number of bytes to skip
    Returns:
      the actual number of bytes skipped
    Throws:
      `ZipException` - if a ZIP file error has occurred
      `IOException` - if an I/O error has occurred
      `IllegalArgumentException` - if `n < 0`
    See Also:
      - `InputStream.skipNBytes(long)`

  - ### close

    public void close() throws IOException
    Closes this input stream and releases any system resources associated with the stream.
    Specified by:
      `close` in interface `AutoCloseable`
    Specified by:
      `close` in interface `Closeable`
    Overrides:
      `close` in class `InflaterInputStream`
    Throws:
      `IOException` - if an I/O error has occurred
    See Also:
      - `FilterInputStream.in`

  - ### createZipEntry

    protected ZipEntry createZipEntry(String name)
    Creates a new `ZipEntry` object for the specified entry name.
    Parameters:
      `name` - the ZIP file entry name
    Returns:
      the ZipEntry just created