A MemoryHandler stores LogRecord objects in a fixed-sized buffer in memory. When the buffer fills up, it discards the oldest record one each time a new record arrives. It maintains a reference to another Handler object, and whenever the push( ) method is called, or whenver a LogRecord arrives with a level at or higher than the pushLevel threshold, it "pushes" all of buffered LogRecord objects to that other Handler object, which typically formats and outputs them to some appropriate destination. Because MemoryHandler never outputs log records itself, it does not use the formatter or encoding properties inherited from its superclass.

When you create a MemoryHandler, you can specify the target Handler object, the size of the in-memory buffer, and the value of the pushLevel property, or you can omit these constructor arguments and rely on system-wide defaults obtained with LogManager.getProperty( ). MemoryHandler also uses LogManager.getProperty( ) to obtain initial values for the level and filter properties inherited from Handler. The table below lists these properties, as well as the target, size, and pushLevel constructor arguments, the value passed to getProperty( ), and the default value used if getProperty( ) returns null. See Handler for further details.

Figure 16-119. java.util.logging.MemoryHandler

public class MemoryHandler extends Handler {
// Public Constructors
     public MemoryHandler( );  
     public MemoryHandler(Handler target, int size, Level pushLevel);  
// Public Instance Methods
     public Level getPushLevel( );                         synchronized
     public void push( );                                  synchronized
     public void setPushLevel(Level newLevel) throws SecurityException;  
// Public Methods Overriding Handler
     public void close( ) throws SecurityException;  
     public void flush( );  
     public boolean isLoggable(LogRecord record);  
     public void publish(LogRecord record);                       synchronized
}