org.knime.core.node.util

Class StringHistory

java.lang.Object

org.knime.core.node.util.StringHistory

public final class StringHistory
extends Object

Utility class that keeps a list of recently used String, mostly used in File-Reader and Writer that keep track of a list of recently accessed file names. This class also makes sure that the list is made persistent and saved to disk when the application closes. The list is read again from file on startup.

Usage in a short way: Determine a (possibly unique) ID for your history to use (I assume that there are not that many?) and get a history object by invoking StringHistory.getInstance(yourID). You can add recently used String to this object by invoking the add(String) method and get a list of String from the getHistory() method which will return the history in the order the add method on the String objects has been called with the last element added being the first element in the history result.

Author:

Bernd Wiswedel, University of Konstanz

Method Summary

Modifier and Type	Method and Description
void	add(String str) Adds a new String to the history.
void	clearHistory() Removes all entries from the history.
String[]	getHistory() Get the history in an array with the most recently added element first.
static StringHistory	getInstance(String id) Get a history for an ID.
static StringHistory	getInstance(String id, int maxEntries) Get a history for an ID.

Methods inherited from class java.lang.Object

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

Method Detail

getInstance

public static StringHistory getInstance(String id)

Get a history for an ID. If that ID doesn't yet exist, a new (empty) history is created.

Parameters:

id - The ID of interest

Returns:

The history for this id. If this id has been used previously, the history is loaded from file.

getInstance

public static StringHistory getInstance(String id,
                                        int maxEntries)

Get a history for an ID. If that ID doesn't yet exist, a new (empty) history is created.

Parameters:

id - The ID of interest

maxEntries - maximal number of entries in the history

Returns:

The history for this id. If this id has been used previously, the history is loaded from file.

Since:

3.2

add

public void add(String str)

Adds a new String to the history. If this string already exists in the history, it is marked as most recently added and will be returned first on a immediate call of getHistory()

Parameters:

str - The string to add.

Throws:

NullPointerException - If argument is null.

getHistory

public String[] getHistory()

Get the history in an array with the most recently added element first.

Returns:

The history.

clearHistory

public void clearHistory()

Removes all entries from the history.