This interface defines a flush( ) method and is implemented by flushable objects such as java.io streams. This interface was added in Java 5.0 to enable java.util.Formatter to distinguish java.lang.Appendable objects that need to be flushed (such as streams) from those that do not (such as StringBuilder objects). See also Closeable.

public interface Flushable {
// Public Instance Methods
     void flush( ) throws IOException;  
}

Implementations

OutputStream, Writer, java.util.Formatter