Package io.nayuki.qrcodegen

Class QrSegment

java.lang.Object
io.nayuki.qrcodegen.QrSegment
public final class QrSegment
extends java.lang.Object
A segment of character/binary/control data in a QR Code symbol. Instances of this class are immutable.

The mid-level way to create a segment is to take the payload data and call a static factory function such as makeNumeric(String). The low-level way to create a segment is to custom-make the bit buffer and call the constructor with appropriate values.

This segment class imposes no length restrictions, but QR Codes have restrictions. Even in the most favorable conditions, a QR Code can only hold 7089 characters of data. Any segment longer than this is meaningless for the purpose of generating QR Codes. This class can represent kanji mode segments, but provides no help in encoding them - see QrSegmentAdvanced for full kanji support.

  • Nested Class Summary

    Nested Classes
    Modifier and Type Class Description
    static class  QrSegment.Mode
    Describes how a segment's data bits are interpreted.

  • Field Summary

    Fields
    Modifier and Type Field Description
    QrSegment.Mode mode
    The mode indicator of this segment.
    int numChars
    The length of this segment's unencoded data.

  • Constructor Summary

    Constructors
    Constructor Description
    QrSegment​(QrSegment.Mode md, int numCh, BitBuffer data)
    Constructs a QR Code segment with the specified attributes and data.

  • Method Summary

    Modifier and Type Method Description
    BitBuffer getData()
    Returns the data bits of this segment.
    static boolean isAlphanumeric​(java.lang.String text)
    Tests whether the specified string can be encoded as a segment in alphanumeric mode.
    static boolean isNumeric​(java.lang.String text)
    Tests whether the specified string can be encoded as a segment in numeric mode.
    static QrSegment makeAlphanumeric​(java.lang.String text)
    Returns a segment representing the specified text string encoded in alphanumeric mode.
    static QrSegment makeBytes​(byte[] data)
    Returns a segment representing the specified binary data encoded in byte mode.
    static QrSegment makeEci​(int assignVal)
    Returns a segment representing an Extended Channel Interpretation (ECI) designator with the specified assignment value.
    static QrSegment makeNumeric​(java.lang.String digits)
    Returns a segment representing the specified string of decimal digits encoded in numeric mode.
    static java.util.List<QrSegment> makeSegments​(java.lang.String text)
    Returns a list of zero or more segments to represent the specified Unicode text string.

    Methods inherited from class java.lang.Object

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

  • Field Details

    • mode

      public final QrSegment.Mode mode
      The mode indicator of this segment. Not null.

    • numChars

      public final int numChars
      The length of this segment's unencoded data. Measured in characters for numeric/alphanumeric/kanji mode, bytes for byte mode, and 0 for ECI mode. Always zero or positive. Not the same as the data's bit length.

  • Constructor Details

    • QrSegment

      public QrSegment​(QrSegment.Mode md, int numCh, BitBuffer data)
      Constructs a QR Code segment with the specified attributes and data. The character count (numCh) must agree with the mode and the bit buffer length, but the constraint isn't checked. The specified bit buffer is cloned and stored.
      Parameters:
      md - the mode (not null)
      numCh - the data length in characters or bytes, which is non-negative
      data - the data bits (not null)
      Throws:
      java.lang.NullPointerException - if the mode or data is null
      java.lang.IllegalArgumentException - if the character count is negative

  • Method Details

    • makeBytes

      public static QrSegment makeBytes​(byte[] data)
      Returns a segment representing the specified binary data encoded in byte mode. All input byte arrays are acceptable.

      Any text string can be converted to UTF-8 bytes ( s.getBytes(StandardCharsets.UTF_8)) and encoded as a byte mode segment.

      Parameters:
      data - the binary data (not null)
      Returns:
      a segment (not null) containing the data
      Throws:
      java.lang.NullPointerException - if the array is null

    • makeNumeric

      public static QrSegment makeNumeric​(java.lang.String digits)
      Returns a segment representing the specified string of decimal digits encoded in numeric mode.
      Parameters:
      digits - the text (not null), with only digits from 0 to 9 allowed
      Returns:
      a segment (not null) containing the text
      Throws:
      java.lang.NullPointerException - if the string is null
      java.lang.IllegalArgumentException - if the string contains non-digit characters

    • makeAlphanumeric

      public static QrSegment makeAlphanumeric​(java.lang.String text)
      Returns a segment representing the specified text string encoded in alphanumeric mode. The characters allowed are: 0 to 9, A to Z (uppercase only), space, dollar, percent, asterisk, plus, hyphen, period, slash, colon.
      Parameters:
      text - the text (not null), with only certain characters allowed
      Returns:
      a segment (not null) containing the text
      Throws:
      java.lang.NullPointerException - if the string is null
      java.lang.IllegalArgumentException - if the string contains non-encodable characters

    • makeSegments

      public static java.util.List<QrSegment> makeSegments​(java.lang.String text)
      Returns a list of zero or more segments to represent the specified Unicode text string. The result may use various segment modes and switch modes to optimize the length of the bit stream.
      Parameters:
      text - the text to be encoded, which can be any Unicode string
      Returns:
      a new mutable list (not null) of segments (not null) containing the text
      Throws:
      java.lang.NullPointerException - if the text is null

    • makeEci

      public static QrSegment makeEci​(int assignVal)
      Returns a segment representing an Extended Channel Interpretation (ECI) designator with the specified assignment value.
      Parameters:
      assignVal - the ECI assignment number (see the AIM ECI specification)
      Returns:
      a segment (not null) containing the data
      Throws:
      java.lang.IllegalArgumentException - if the value is outside the range [0, 106)

    • isNumeric

      public static boolean isNumeric​(java.lang.String text)
      Tests whether the specified string can be encoded as a segment in numeric mode. A string is encodable iff each character is in the range 0 to 9.
      Parameters:
      text - the string to test for encodability (not null)
      Returns:
      true iff each character is in the range 0 to 9.
      Throws:
      java.lang.NullPointerException - if the string is null
      See Also:
      makeNumeric(String)

    • isAlphanumeric

      public static boolean isAlphanumeric​(java.lang.String text)
      Tests whether the specified string can be encoded as a segment in alphanumeric mode. A string is encodable iff each character is in the following set: 0 to 9, A to Z (uppercase only), space, dollar, percent, asterisk, plus, hyphen, period, slash, colon.
      Parameters:
      text - the string to test for encodability (not null)
      Returns:
      true iff each character is in the alphanumeric mode character set
      Throws:
      java.lang.NullPointerException - if the string is null
      See Also:
      makeAlphanumeric(String)

    • getData

      public BitBuffer getData()
      Returns the data bits of this segment.
      Returns:
      a new copy of the data bits (not null)