Module java.desktop
Package javax.swing.text

Class Segment

  • All Implemented Interfaces:
    CharSequence, Cloneable, CharacterIterator
    public class Segment
extends Object
implements Cloneable, CharacterIterator, CharSequence
    A segment of a character array representing a fragment of text. It should be treated as immutable even though the array is directly accessible. This gives fast access to fragments of text without the overhead of copying around characters. This is effectively an unprotected String.

    The Segment implements the java.text.CharacterIterator interface to support use with the i18n support without copying text into a string.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      char[] array
      This is the array containing the text of interest.
      int count
      This is the number of array elements that make up the text of interest.
      int offset
      This is the offset into the array that the desired text begins.

    • Constructor Summary

      Constructors 
      Constructor Description
      Segment()
      Creates a new segment.
      Segment​(char[] array, int offset, int count)
      Creates a new segment referring to an existing array.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      char charAt​(int index)
      Returns the char value at the specified index.
      Object clone()
      Creates a shallow copy.
      char current()
      Gets the character at the current position (as returned by getIndex()).
      char first()
      Sets the position to getBeginIndex() and returns the character at that position.
      int getBeginIndex()
      Returns the start index of the text.
      int getEndIndex()
      Returns the end index of the text.
      int getIndex()
      Returns the current index.
      boolean isPartialReturn()
      Flag to indicate that partial returns are valid.
      char last()
      Sets the position to getEndIndex()-1 (getEndIndex() if the text is empty) and returns the character at that position.
      int length()
      Returns the length of this character sequence.
      char next()
      Increments the iterator's index by one and returns the character at the new index.
      char previous()
      Decrements the iterator's index by one and returns the character at the new index.
      char setIndex​(int position)
      Sets the position to the specified position in the text and returns that character.
      void setPartialReturn​(boolean p)
      Flag to indicate that partial returns are valid.
      CharSequence subSequence​(int start, int end)
      Returns a CharSequence that is a subsequence of this sequence.
      String toString()
      Converts a segment into a String.

    • Field Detail

      • array

        public char[] array
        This is the array containing the text of interest. This array should never be modified; it is available only for efficiency.

      • offset

        public int offset
        This is the offset into the array that the desired text begins.

      • count

        public int count
        This is the number of array elements that make up the text of interest.

    • Constructor Detail

      • Segment

        public Segment()
        Creates a new segment.

      • Segment

        public Segment​(char[] array,
               int offset,
               int count)
        Creates a new segment referring to an existing array.
        Parameters:
        array - the array to refer to
        offset - the offset into the array
        count - the number of characters

    • Method Detail

      • setPartialReturn

        public void setPartialReturn​(boolean p)
        Flag to indicate that partial returns are valid. If the flag is true, an implementation of the interface method Document.getText(position,length,Segment) should return as much text as possible without making a copy. The default state of the flag is false which will cause Document.getText(position,length,Segment) to provide the same return behavior it always had, which may or may not make a copy of the text depending upon the request.
        Parameters:
        p - whether or not partial returns are valid.
        Since:
        1.4

      • isPartialReturn

        public boolean isPartialReturn()
        Flag to indicate that partial returns are valid.
        Returns:
        whether or not partial returns are valid.
        Since:
        1.4

      • first

        public char first()
        Sets the position to getBeginIndex() and returns the character at that position.
        Specified by:
        first in interface CharacterIterator
        Returns:
        the first character in the text, or DONE if the text is empty
        Since:
        1.3
        See Also:
        getBeginIndex()

      • last

        public char last()
        Sets the position to getEndIndex()-1 (getEndIndex() if the text is empty) and returns the character at that position.
        Specified by:
        last in interface CharacterIterator
        Returns:
        the last character in the text, or DONE if the text is empty
        Since:
        1.3
        See Also:
        getEndIndex()

      • current

        public char current()
        Gets the character at the current position (as returned by getIndex()).
        Specified by:
        current in interface CharacterIterator
        Returns:
        the character at the current position or DONE if the current position is off the end of the text.
        Since:
        1.3
        See Also:
        getIndex()

      • next

        public char next()
        Increments the iterator's index by one and returns the character at the new index. If the resulting index is greater or equal to getEndIndex(), the current index is reset to getEndIndex() and a value of DONE is returned.
        Specified by:
        next in interface CharacterIterator
        Returns:
        the character at the new position or DONE if the new position is off the end of the text range.
        Since:
        1.3

      • previous

        public char previous()
        Decrements the iterator's index by one and returns the character at the new index. If the current index is getBeginIndex(), the index remains at getBeginIndex() and a value of DONE is returned.
        Specified by:
        previous in interface CharacterIterator
        Returns:
        the character at the new position or DONE if the current position is equal to getBeginIndex().
        Since:
        1.3

      • setIndex

        public char setIndex​(int position)
        Sets the position to the specified position in the text and returns that character.
        Specified by:
        setIndex in interface CharacterIterator
        Parameters:
        position - the position within the text. Valid values range from getBeginIndex() to getEndIndex(). An IllegalArgumentException is thrown if an invalid value is supplied.
        Returns:
        the character at the specified position or DONE if the specified position is equal to getEndIndex()
        Since:
        1.3

      • getBeginIndex

        public int getBeginIndex()
        Returns the start index of the text.
        Specified by:
        getBeginIndex in interface CharacterIterator
        Returns:
        the index at which the text begins.
        Since:
        1.3

      • getEndIndex

        public int getEndIndex()
        Returns the end index of the text. This index is the index of the first character following the end of the text.
        Specified by:
        getEndIndex in interface CharacterIterator
        Returns:
        the index after the last character in the text
        Since:
        1.3

      • getIndex

        public int getIndex()
        Returns the current index.
        Specified by:
        getIndex in interface CharacterIterator
        Returns:
        the current index.
        Since:
        1.3

      • charAt

        public char charAt​(int index)
        Returns the char value at the specified index. An index ranges from zero to length() - 1. The first char value of the sequence is at index zero, the next at index one, and so on, as for array indexing.

        If the char value specified by the index is a surrogate, the surrogate value is returned.

        Specified by:
        charAt in interface CharSequence
        Parameters:
        index - the index of the char value to be returned
        Returns:
        the specified char value
        Since:
        1.6

      • length

        public int length()
        Returns the length of this character sequence. The length is the number of 16-bit chars in the sequence.
        Specified by:
        length in interface CharSequence
        Returns:
        the number of chars in this sequence
        Since:
        1.6

      • subSequence

        public CharSequence subSequence​(int start,
                                int end)
        Returns a CharSequence that is a subsequence of this sequence. The subsequence starts with the char value at the specified index and ends with the char value at index end - 1. The length (in chars) of the returned sequence is end - start, so if start == end then an empty sequence is returned.
        Specified by:
        subSequence in interface CharSequence
        Parameters:
        start - the start index, inclusive
        end - the end index, exclusive
        Returns:
        the specified subsequence
        Since:
        1.6