Class DefaultHistory

java.lang.Object
org.jline.reader.impl.history.DefaultHistory
All Implemented Interfaces:
Iterable<History.Entry>, History
public class DefaultHistory extends Object implements History
Default implementation of History with file-based persistent storage.

This class provides a complete implementation of the History interface with the following features:

  • In-memory storage of history entries with configurable size limits
  • Persistent storage in a text file with configurable location and size limits
  • Support for timestamped history entries
  • Filtering of entries based on patterns defined in the LineReader.HISTORY_IGNORE variable
  • Options to ignore duplicates, reduce blanks, and ignore commands starting with spaces
  • Incremental saving of history entries
  • History navigation (previous/next, first/last, etc.)

The history file format is either plain text with one command per line, or if LineReader.Option.HISTORY_TIMESTAMPED is set, each line starts with a timestamp in milliseconds since epoch, followed by a colon and the command text.

Applications using this class should install a shutdown hook to call save() to ensure history is saved to disk when the application exits.

Example usage: 

LineReader reader = LineReaderBuilder.builder()
    .variable(LineReader.HISTORY_FILE, Paths.get(System.getProperty("user.home"), ".myapp_history"))
    .build();
// History is automatically attached to the reader

// To save history manually:
((DefaultHistory) reader.getHistory()).save();
See Also:

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    protected static class 
    DefaultHistory.EntryImpl
    Default implementation of the History.Entry interface.

    Nested classes/interfaces inherited from interface History

    History.Entry

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final int
    DEFAULT_HISTORY_FILE_SIZE
    Default maximum number of history entries to keep in the history file.
    static final int
    DEFAULT_HISTORY_SIZE
    Default maximum number of history entries to keep in memory.

  • Constructor Summary

    Constructors
    Constructor
    Description
    DefaultHistory()
    Creates a new DefaultHistory instance.
    DefaultHistory(LineReader reader)
    Creates a new DefaultHistory instance and attaches it to the specified LineReader.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    add(Instant time, String line)
    Adds a new entry to the history.
    protected void
    addHistoryLine(Path path, String line)
    Adds a history line to the specified history file.
    protected void
    addHistoryLine(Path path, String line, boolean checkDuplicates)
    Adds a history line to the specified history file with an option to check for duplicates.
    void
    append(Path file, boolean incremental)
    Appends history entries to the specified file.
    void
    attach(LineReader reader)
    Attaches this history to a LineReader.
    protected DefaultHistory.EntryImpl
    createEntry(int index, Instant time, String line)
    Create a history entry.
    String
    current()
    Returns the text of the history entry at the current cursor position.
    int
    first()
    Returns the index of the first element in the history.
    String
    get(int index)
    Returns the history item at the specified index.
    int
    index()
    Returns the current index in the history.
    protected void
    internalAdd(Instant time, String line)
    Adds a line to the history with the specified timestamp.
    protected void
    internalAdd(Instant time, String line, boolean checkDuplicates)
    Adds a line to the history with the specified timestamp and an option to check for duplicates.
    boolean
    isEmpty()
    Checks if the history is empty.
    ListIterator<History.Entry>
    iterator(int index)
    Returns a list iterator over the history entries starting at the specified index.
    int
    last()
    Returns the index of the last element in the history.
    void
    load()
    Loads history from the file specified by the LineReader.HISTORY_FILE variable.
    protected boolean
    matchPatterns(String patterns, String line)
    Checks if a line matches any of the specified patterns.
    boolean
    moveTo(int index)
    Moves the history cursor to the specified index.
    void
    moveToEnd()
    Moves the history cursor to the end of the history buffer.
    boolean
    moveToFirst()
    Moves the history cursor to the first entry.
    boolean
    moveToLast()
    Moves the history cursor to the last entry.
    boolean
    next()
    Moves the history cursor to the next (newer) entry.
    boolean
    previous()
    Moves the history cursor to the previous (older) entry.
    void
    purge()
    Clears the history and deletes the history file.
    void
    read(Path file, boolean checkDuplicates)
    Reads history entries from the specified file and adds them to the current history.
    void
    resetIndex()
    Reset index after remove
    void
    save()
    Saves the history to the default history file.
    int
    size()
    Returns the number of items in the history.
    Spliterator<History.Entry>
    spliterator()
     
    String
    toString()
     
    protected void
    trimHistory(Path path, int max)
    Trims the history file to the specified maximum number of entries.
    void
    write(Path file, boolean incremental)
    Writes the history to the specified file, optionally replacing the existing file.

    Methods inherited from class Object

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

    Methods inherited from interface History

    add, isPersistable, iterator, reverseIterator, reverseIterator

    Methods inherited from interface Iterable

    forEach

  • Field Details

    • DEFAULT_HISTORY_SIZE

      public static final int DEFAULT_HISTORY_SIZE
      Default maximum number of history entries to keep in memory. This value is used when the LineReader.HISTORY_SIZE variable is not set.
      See Also:

    • DEFAULT_HISTORY_FILE_SIZE

      public static final int DEFAULT_HISTORY_FILE_SIZE
      Default maximum number of history entries to keep in the history file. This value is used when the LineReader.HISTORY_FILE_SIZE variable is not set.
      See Also:

  • Constructor Details

    • DefaultHistory

      public DefaultHistory()
      Creates a new DefaultHistory instance.

    • DefaultHistory

      public DefaultHistory(LineReader reader)
      Creates a new DefaultHistory instance and attaches it to the specified LineReader.
      Parameters:
      reader - the LineReader to attach to

  • Method Details

    • attach

      public void attach(LineReader reader)
      Attaches this history to a LineReader.

      This method associates the history with a LineReader and loads the history from the file specified by the LineReader.HISTORY_FILE variable. If the history is already attached to the given reader, this method does nothing.

      Specified by:
      attach in interface History
      Parameters:
      reader - the LineReader to attach this history to

    • load

      public void load() throws IOException
      Loads history from the file specified by the LineReader.HISTORY_FILE variable.

      This method clears the current history and loads entries from the history file. If the file doesn't exist or can't be read, the history will be cleared. If individual lines in the history file are malformed, they will be skipped.

      Specified by:
      load in interface History
      Throws:
      IOException - if an I/O error occurs while reading the history file

    • read

      public void read(Path file, boolean checkDuplicates) throws IOException
      Reads history entries from the specified file and adds them to the current history.

      Unlike load(), this method does not clear the existing history before adding entries from the file. If the file doesn't exist or can't be read, the history will be cleared. If individual lines in the history file are malformed, they will be skipped.

      Specified by:
      read in interface History
      Parameters:
      file - the file to read history from, or null to use the default history file
      checkDuplicates - whether to check for and skip duplicate entries
      Throws:
      IOException - if an I/O error occurs while reading the history file

    • addHistoryLine

      protected void addHistoryLine(Path path, String line)
      Adds a history line to the specified history file.
      Parameters:
      path - the path to the history file
      line - the line to add

    • addHistoryLine

      protected void addHistoryLine(Path path, String line, boolean checkDuplicates)
      Adds a history line to the specified history file with an option to check for duplicates.
      Parameters:
      path - the path to the history file
      line - the line to add
      checkDuplicates - whether to check for duplicate entries

    • purge

      public void purge() throws IOException
      Clears the history and deletes the history file.

      This method removes all history entries from memory and deletes the history file if it exists.

      Specified by:
      purge in interface History
      Throws:
      IOException - if an I/O error occurs while deleting the history file

    • write

      public void write(Path file, boolean incremental) throws IOException
      Writes the history to the specified file, optionally replacing the existing file.

      If the file exists, it will be deleted and recreated. If incremental is true, only entries that haven't been saved before will be written.

      Specified by:
      write in interface History
      Parameters:
      file - the file to write history to, or null to use the default history file
      incremental - whether to write only new entries (true) or all entries (false)
      Throws:
      IOException - if an I/O error occurs while writing the history file

    • append

      public void append(Path file, boolean incremental) throws IOException
      Appends history entries to the specified file.

      Unlike write(Path, boolean), this method does not delete the existing file before writing. If incremental is true, only entries that haven't been saved before will be appended.

      Specified by:
      append in interface History
      Parameters:
      file - the file to append history to, or null to use the default history file
      incremental - whether to append only new entries (true) or all entries (false)
      Throws:
      IOException - if an I/O error occurs while appending to the history file

    • save

      public void save() throws IOException
      Saves the history to the default history file.

      This method appends any new history entries (those that haven't been saved before) to the history file. It's typically called when the application exits to ensure that history is preserved.

      Specified by:
      save in interface History
      Throws:
      IOException - if an I/O error occurs while saving the history file

    • trimHistory

      protected void trimHistory(Path path, int max) throws IOException
      Trims the history file to the specified maximum number of entries.
      Parameters:
      path - the path to the history file
      max - the maximum number of entries to keep
      Throws:
      IOException - if an I/O error occurs

    • createEntry

      protected DefaultHistory.EntryImpl createEntry(int index, Instant time, String line)
      Create a history entry. Subclasses may override to use their own entry implementations.
      Parameters:
      index - index of history entry
      time - entry creation time
      line - the entry text
      Returns:
      entry object

    • size

      public int size()
      Description copied from interface: History
      Returns the number of items in the history.
      Specified by:
      size in interface History
      Returns:
      the number of history items

    • isEmpty

      public boolean isEmpty()
      Description copied from interface: History
      Checks if the history is empty.
      Specified by:
      isEmpty in interface History
      Returns:
      true if the history contains no items

    • index

      public int index()
      Description copied from interface: History
      Returns the current index in the history.
      Specified by:
      index in interface History
      Returns:
      the current index

    • first

      public int first()
      Description copied from interface: History
      Returns the index of the first element in the history.
      Specified by:
      first in interface History
      Returns:
      the index of the first history item

    • last

      public int last()
      Description copied from interface: History
      Returns the index of the last element in the history.
      Specified by:
      last in interface History
      Returns:
      the index of the last history item

    • get

      public String get(int index)
      Description copied from interface: History
      Returns the history item at the specified index.
      Specified by:
      get in interface History
      Parameters:
      index - the index of the history item to retrieve
      Returns:
      the history item at the specified index

    • add

      public void add(Instant time, String line)
      Adds a new entry to the history.

      This method adds a new entry to the history with the specified timestamp and command text. The entry may be filtered based on various criteria such as:

      If LineReader.Option.HISTORY_INCREMENTAL is set, the history will be saved to disk after adding the entry.

      Specified by:
      add in interface History
      Parameters:
      time - the timestamp for the new entry
      line - the command text for the new entry
      Throws:
      NullPointerException - if time or line is null

    • matchPatterns

      protected boolean matchPatterns(String patterns, String line)
      Checks if a line matches any of the specified patterns.
      Parameters:
      patterns - the patterns to match against, separated by '|'
      line - the line to check
      Returns:
      true if the line matches any of the patterns

    • internalAdd

      protected void internalAdd(Instant time, String line)
      Adds a line to the history with the specified timestamp.
      Parameters:
      time - the timestamp for the history entry
      line - the line to add

    • internalAdd

      protected void internalAdd(Instant time, String line, boolean checkDuplicates)
      Adds a line to the history with the specified timestamp and an option to check for duplicates.
      Parameters:
      time - the timestamp for the history entry
      line - the line to add
      checkDuplicates - whether to check for duplicate entries

    • iterator

      public ListIterator<History.Entry> iterator(int index)
      Description copied from interface: History
      Returns a list iterator over the history entries starting at the specified index.
      Specified by:
      iterator in interface History
      Parameters:
      index - the index to start iterating from
      Returns:
      a list iterator over the history entries

    • spliterator

      public Spliterator<History.Entry> spliterator()
      Specified by:
      spliterator in interface Iterable<History.Entry>

    • resetIndex

      public void resetIndex()
      Description copied from interface: History
      Reset index after remove
      Specified by:
      resetIndex in interface History

    • moveToLast

      public boolean moveToLast()
      Moves the history cursor to the last entry.

      This positions the cursor at the most recent history entry, which is one position before the position set by moveToEnd(). This is typically used when starting to navigate backward through history.

      Specified by:
      moveToLast in interface History
      Returns:
      true if the cursor was moved, false if there were no history entries or the cursor was already at the last entry

    • moveTo

      public boolean moveTo(int index)
      Moves the history cursor to the specified index.

      This positions the cursor at the history entry with the given index, if it exists. The index is absolute, taking into account the offset of the history buffer.

      Specified by:
      moveTo in interface History
      Parameters:
      index - the absolute index to move to
      Returns:
      true if the cursor was moved, false if the index was out of range

    • moveToFirst

      public boolean moveToFirst()
      Moves the history cursor to the first entry.

      This positions the cursor at the oldest history entry in the buffer. This is typically used when starting to navigate forward through history.

      Specified by:
      moveToFirst in interface History
      Returns:
      true if the cursor was moved, false if there were no history entries or the cursor was already at the first entry

    • moveToEnd

      public void moveToEnd()
      Moves the history cursor to the end of the history buffer.

      This positions the cursor after the last history entry, which represents the current input line (not yet in history). This is the default position when not navigating through history.

      Specified by:
      moveToEnd in interface History

    • current

      public String current()
      Returns the text of the history entry at the current cursor position.

      If the cursor is at the end of the history (after the last entry), this method returns an empty string.

      Specified by:
      current in interface History
      Returns:
      the text of the current history entry, or an empty string if at the end

    • previous

      public boolean previous()
      Moves the history cursor to the previous (older) entry.

      This is typically called when the user presses the up arrow key to navigate backward through history. If the cursor is already at the first entry, this method does nothing and returns false.

      Specified by:
      previous in interface History
      Returns:
      true if the cursor was moved, false if already at the first entry

    • next

      public boolean next()
      Moves the history cursor to the next (newer) entry.

      This is typically called when the user presses the down arrow key to navigate forward through history. If the cursor is already at the end of history, this method does nothing and returns false.

      Specified by:
      next in interface History
      Returns:
      true if the cursor was moved, false if already at the end of history

    • toString

      public String toString()
      Overrides:
      toString in class Object