Package org.jline.reader

Interface History

All Superinterfaces:

Iterable<History.Entry>

All Known Implementing Classes:

DefaultHistory

public interface History
extends Iterable<History.Entry>

Console command history management interface.

The History interface provides functionality for storing, retrieving, and navigating through previously entered commands. It allows users to recall and reuse commands they've typed before, which is a fundamental feature of interactive command-line interfaces.

History implementations typically support:

• Adding new entries as commands are executed
• Navigating backward and forward through history
• Persisting history to a file for use across sessions
• Filtering or ignoring certain commands based on patterns

Each history entry contains the command text along with metadata such as the timestamp when it was executed.

The default implementation is DefaultHistory.

Since:

2.3

See Also:

• LineReader.getHistory()
• LineReaderBuilder.history(History)

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static interface	History.Entry	Represents a single history entry containing a command line and its metadata.

Method Summary

Modifier and Type	Method	Description
default void	add(String line)
void	add(Instant time, String line)	Adds a new item to the history with the specified timestamp.
void	append(Path file, boolean incremental)	Append history to the file.
void	attach(LineReader reader)	Initialize the history for the given reader.
String	current()	Return the content of the current buffer.
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.
default boolean	isEmpty()	Checks if the history is empty.
default boolean	isPersistable(History.Entry entry)	Check if an entry should be persisted or not.
default ListIterator<History.Entry>	iterator()
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()	Load history.
boolean	moveTo(int index)	Move to the specified index in the history
void	moveToEnd()	Move to the end of the history buffer.
boolean	moveToFirst()	Moves the history index to the first entry.
boolean	moveToLast()	This moves the history to the last entry.
boolean	next()	Move the pointer to the next element in the buffer.
boolean	previous()	Move the pointer to the previous element in the buffer.
void	purge()	Purge history.
void	read(Path file, boolean checkDuplicates)	Read history from the file.
void	resetIndex()	Reset index after remove
default Iterator<History.Entry>	reverseIterator()
default Iterator<History.Entry>	reverseIterator(int index)
void	save()	Save history.
int	size()	Returns the number of items in the history.
void	write(Path file, boolean incremental)	Write history to the file.

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Method Details

attach

void attach(LineReader reader)

Initialize the history for the given reader.

Parameters:

reader - the reader to attach to

load

void load()
   throws IOException

Load history.

Throws:

IOException - if a problem occurs

save

void save()
   throws IOException

Save history.

Throws:

IOException - if a problem occurs

write

void write(Path file,
 boolean incremental)
    throws IOException

Write history to the file. If incremental only the events that are new since the last incremental operation to the file are added.

Parameters:

file - History file

incremental - If true incremental write operation is performed.

Throws:

IOException - if a problem occurs

append

void append(Path file,
 boolean incremental)
     throws IOException

Append history to the file. If incremental only the events that are new since the last incremental operation to the file are added.

Parameters:

file - History file

incremental - If true incremental append operation is performed.

Throws:

IOException - if a problem occurs

read

void read(Path file,
 boolean checkDuplicates)
   throws IOException

Read history from the file. If checkDuplicates is true only the events that are not contained within the internal list are added.

Parameters:

file - History file

checkDuplicates - If true, duplicate history entries will be discarded

Throws:

IOException - if a problem occurs

purge

void purge()
    throws IOException

Purge history.

Throws:

IOException - if a problem occurs

size

int size()

Returns the number of items in the history.

Returns:

the number of history items

isEmpty

default boolean isEmpty()

Checks if the history is empty.

Returns:

true if the history contains no items

index

int index()

Returns the current index in the history.

Returns:

the current index

first

int first()

Returns the index of the first element in the history.

Returns:

the index of the first history item

last

int last()

Returns the index of the last element in the history.

Returns:

the index of the last history item

get

String get(int index)

Returns the history item at the specified index.

Parameters:

index - the index of the history item to retrieve

Returns:

the history item at the specified index

add

default void add(String line)

add

void add(Instant time,
 String line)

Adds a new item to the history with the specified timestamp.

Parameters:

time - the timestamp for the history item

line - the line to add to the history

isPersistable

default boolean isPersistable(History.Entry entry)

Check if an entry should be persisted or not.

Parameters:

entry - the entry to check

Returns:

true if the given entry should be persisted, false otherwise

iterator

ListIterator<History.Entry> iterator(int index)

Returns a list iterator over the history entries starting at the specified index.

Parameters:

index - the index to start iterating from

Returns:

a list iterator over the history entries

iterator

default ListIterator<History.Entry> iterator()

Specified by:

iterator in interface Iterable<History.Entry>

reverseIterator

default Iterator<History.Entry> reverseIterator()

reverseIterator

default Iterator<History.Entry> reverseIterator(int index)

current

String current()

Return the content of the current buffer.

Returns:

the content of the current buffer

previous

boolean previous()

Move the pointer to the previous element in the buffer.

Returns:

true if we successfully went to the previous element

next

boolean next()

Move the pointer to the next element in the buffer.

Returns:

true if we successfully went to the next element

moveToFirst

boolean moveToFirst()

Moves the history index to the first entry.

Returns:

Return false if there are no iterator in the history or if the history is already at the beginning.

moveToLast

boolean moveToLast()

This moves the history to the last entry. This entry is one position before the moveToEnd() position.

Returns:

Returns false if there were no history iterator or the history index was already at the last entry.

moveTo

boolean moveTo(int index)

Move to the specified index in the history

Parameters:

index - The index to move to.

Returns:

Returns true if the index was moved.

moveToEnd

void moveToEnd()

Move to the end of the history buffer. This will be a blank entry, after all of the other iterator.

resetIndex

void resetIndex()

Reset index after remove