Package jmri

Class Block

  • All Implemented Interfaces:
    java.lang.Comparable<NamedBean>, PropertyChangeProvider, NamedBean, PhysicalLocationReporter
    Direct Known Subclasses:
    OBlock
    public class Block
extends AbstractNamedBean
implements PhysicalLocationReporter
    Represents a particular piece of track, more informally a "Block".

    A Block (at least in this implementation) corresponds exactly to the track covered by at most one sensor. That could be generalized in the future.

    As trains move around the layout, a set of Block objects that are attached to sensors can interact to keep track of which train is where, going in which direction. As a result of this, the set of Block objects pass around "token" (value) Objects representing the trains. This could be e.g. a Throttle to control the train, or something else.

    A block maintains a "direction" flag that is set from the direction of the incoming train. When an arriving train is detected via the connected sensor and the Block's status information is sufficient to determine that it is arriving via a particular Path, that Path's getFromBlockDirection becomes the direction of the train in this Block.

    Optionally, a Block can be associated with a Reporter. In this case, the Reporter will provide the Block with the "token" (value). This could be e.g an RFID reader reading an ID tag attached to a locomotive. Depending on the specific Reporter implementation, either the current reported value or the last reported value will be relevant, this can be configured.

    Objects of this class are Named Beans, so can be manipulated through tables, have listeners, etc.

    The type letter used in the System Name is 'B' for 'Block'. The default implementation is not system-specific, so a system letter of 'I' is appropriate. This leads to system names like "IB201".

    Issues:

    • The tracking doesn't handle a train pulling in behind another well:
      • When the 2nd train arrives, the Sensor is already active, so the value is unchanged (but the value can only be a single object anyway)
      • When the 1st train leaves, the Sensor stays active, so the value remains that of the 1st train
    • The assumption is that a train will only go through a set turnout. For example, a train could come into the turnout block from the main even if the turnout is set to the siding. (Ignoring those layouts where this would cause a short; it doesn't do so on all layouts)
    • Does not handle closely-following trains where there is only one electrical block per signal. To do this, it probably needs some type of "assume a train doesn't back up" logic. A better solution is to have multiple sensors and Block objects between each signal head.
    • If a train reverses in a block and goes back the way it came (e.g. b1 to b2 to b1), the block that's re-entered will get an updated direction, but the direction of this block (b2 in the example) is not updated. In other words, we're not noticing that the train must have reversed to go back out.

    Do not assume that a Block object uniquely represents a piece of track. To allow independent development, it must be possible for multiple Block objects to take care of a particular section of track.

    Possible state values:

    • UNKNOWN - The sensor shows UNKNOWN, so this block doesn't know if it's occupied or not.
    • INCONSISTENT - The sensor shows INCONSISTENT, so this block doesn't know if it's occupied or not.
    • OCCUPIED - This sensor went active. Note that OCCUPIED will be set even if the logic is unable to figure out which value to take.
    • UNOCCUPIED - No content, because the sensor has determined this block is unoccupied.
    • UNDETECTED - No sensor configured.

    Possible Curvature attributes (optional) User can set the curvature if desired for use in automatic running of trains, to indicate where slow down is required.

    • NONE - No curvature in Block track, or Not entered.
    • GRADUAL - Gradual curve - no action by engineer is warranted - full speed OK
    • TIGHT - Tight curve in Block track - Train should slow down some
    • SEVERE - Severe curve in Block track - Train should slow down a lot

    The length of the block may also optionally be entered if desired. This attribute is for use in automatic running of trains. Length should be the actual length of model railroad track in the block. It is always stored here in millimeter units. A length of 0.0 indicates no entry of length by the user.

    State diagram for train tracking

    • Field Detail

      • UNDETECTED

        public static final int UNDETECTED
        Undetected status, i.e a "Dark" block. A Block with unknown status could be waiting on feedback from a Sensor, hence undetected may be more appropriate if no Sensor.

        OBlocks use this constant in combination with other OBlock status flags. Block uses this constant as initial status, also when a Sensor is unset from the block.

        See Also:
        Constant Field Values

      • OCC_SENSOR_CHANGE

        public static final java.lang.String OCC_SENSOR_CHANGE
        Property name change fired when a Sensor is set to / removed from a Block. The fired event includes old value: Sensor Bean Object if previously set, else null new value: Sensor Bean Object if being set, may be null if Sensor removed.
        See Also:
        Constant Field Values

      • BLOCK_REPORTER_CHANGE

        public static final java.lang.String BLOCK_REPORTER_CHANGE
        Property name change fired when a Sensor is set to / removed from a Block. The fired event includes old value: Sensor Bean Object if previously set, else null new value: Sensor Bean Object if being set, may be null if Sensor removed.
        See Also:
        Constant Field Values

      • BLOCK_REPORTING_CURRENT

        public static final java.lang.String BLOCK_REPORTING_CURRENT
        Property name change fired when the Block reporting Current flag changes. The fired event includes old value: previous value, Boolean. new value: new value, Boolean.
        See Also:
        Constant Field Values

      • BLOCK_PERMISSIVE_CHANGE

        public static final java.lang.String BLOCK_PERMISSIVE_CHANGE
        Property name change fired when the Block Permissive Status changes. The fired event includes old value: previous permissive status. new value: new permissive status.
        See Also:
        Constant Field Values

      • BLOCK_SPEED_CHANGE

        public static final java.lang.String BLOCK_SPEED_CHANGE
        Property name change fired when the Block Speed changes. The fired event includes old value: previous speed String. new value: new speed String.
        See Also:
        Constant Field Values

      • BLOCK_CURVATURE_CHANGE

        public static final java.lang.String BLOCK_CURVATURE_CHANGE
        Property name change fired when the Block Curvature changes. The fired event includes old value: previous Block Curvature Constant. new value: new Block Curvature Constant.
        See Also:
        Constant Field Values

      • BLOCK_LENGTH_CHANGE

        public static final java.lang.String BLOCK_LENGTH_CHANGE
        Property name change fired when the Block Length changes. The fired event includes old value: previous float length (mm). new value: new float length (mm).
        See Also:
        Constant Field Values

    • Constructor Detail

      • Block

        public Block​(java.lang.String systemName)
        Create a new Block.
        Parameters:
        systemName - Block System Name.

      • Block

        public Block​(java.lang.String systemName,
             java.lang.String userName)
        Create a new Block.
        Parameters:
        systemName - system name.
        userName - user name.

    • Method Detail

      • toDebugString

        public java.lang.String toDebugString()
        Create a Debug String, this should only be used for debugging...
        Returns:
        Block User name, System name, current state as string value.

      • setSensor

        public boolean setSensor​(java.lang.String pName)
        Set the sensor by name. Fires propertyChange "OccupancySensorChange" when changed.
        Parameters:
        pName - the name of the Sensor to set
        Returns:
        true if a Sensor is set and is not null; false otherwise

      • setNamedSensor

        public void setNamedSensor​(NamedBeanHandle<Sensor> s)
        Set Block Occupancy Sensor. If Sensor set, Adds PCL, sets Block Occupancy Status to Sensor. Block State PropertyChange Event will fire. Does NOT route initial Sensor Status via goingUnknown() / goingActive() etc.

        If Sensor null, removes PCL on previous Sensor, sets Block status to UNDETECTED.

        Parameters:
        s - Handle for Sensor.

      • getSensor

        public Sensor getSensor()
        Get the Block Occupancy Sensor.
        Returns:
        Sensor if one attached to Block, may be null.

      • setReporter

        public void setReporter​(Reporter reporter)
        Set the Reporter that should provide the data value for this block. Fires propertyChange "BlockReporterChange" when changed.
        Parameters:
        reporter - Reporter object to link, or null to clear
        See Also:
        Reporter

      • getReporter

        public Reporter getReporter()
        Retrieve the Reporter that is linked to this Block
        Returns:
        linked Reporter object, or null if not linked
        See Also:
        Reporter

      • setReportingCurrent

        public void setReportingCurrent​(boolean reportingCurrent)
        Define if the Block's value should be populated from the current report or from the last report. Fires propertyChange "BlockReportingCurrent" when changed.
        Parameters:
        reportingCurrent - true if to use current report; false if to use last report
        See Also:
        Reporter

      • getState

        public int getState()
        Get the Block State. OBlocks may well return a combination of states, Blocks will return a single State.
        Specified by:
        getState in interface NamedBean
        Returns:
        Block state.

      • addPath

        public void addPath​(@Nonnull
                    Path p)
        Add a Path to List of Paths.
        Parameters:
        p - Path to add, not null.

      • removePath

        public void removePath​(Path p)
        Remove a Path from the Block.
        Parameters:
        p - Path to remove.

      • hasPath

        public boolean hasPath​(Path p)
        Check if Block has a particular Path.
        Parameters:
        p - Path to test against.
        Returns:
        true if Block has the Path, else false.

      • getPaths

        @Nonnull
public java.util.List<Path> getPaths()
        Get a copy of the list of Paths.
        Returns:
        the paths or an empty list

      • setState

        public void setState​(int v)
        Provide a general method for updating the report. Fires propertyChange "state" when called.
        Specified by:
        setState in interface NamedBean
        Parameters:
        v - the new state

      • setValue

        public void setValue​(java.lang.Object value)
        Set the value retained by this Block. Also used when the Block itself gathers a value from an adjacent Block. This can be overridden in a subclass if e.g. you want to keep track of Blocks elsewhere, but make sure you also eventually invoke the super.setValue() here. Fires propertyChange "value" when changed.
        Parameters:
        value - The new Object resident in this block, or null if none

      • getValue

        public java.lang.Object getValue()
        Get the Block Contents Value.
        Returns:
        object with current value, could be null.

      • setDirection

        public void setDirection​(int direction)
        Set Block Direction of Travel. Fires propertyChange "direction" when changed.
        Parameters:
        direction - Path Constant form, see Path.java

      • getDirection

        public int getDirection()
        Get Block Direction of Travel.
        Returns:
        direction in Path Constant form, see Path.java

      • addBlockDenyList

        public void addBlockDenyList​(@Nonnull
                             java.lang.String pName)
        Add to the Block Deny List. The block deny list, is used by higher level code, to determine if traffic/trains should be allowed to enter from an attached block, the list only deals with blocks that access should be denied from.

        If we want to prevent traffic from following from this Block to another, then this Block must be added to the deny list of the other Block. By default no Block is barred, so traffic flow is bi-directional.

        Parameters:
        pName - name of the block to add, which must exist

      • getDeniedBlocks

        public java.util.List<java.lang.String> getDeniedBlocks()

      • isBlockDenied

        public boolean isBlockDenied​(java.lang.String deny)

      • getPermissiveWorking

        public boolean getPermissiveWorking()
        Get if Block can have permissive working. Blocks default to non-permissive, i.e. false.
        Returns:
        true if permissive, else false.

      • setPermissiveWorking

        public void setPermissiveWorking​(boolean w)
        Set Block as permissive. Fires propertyChange "BlockPermissiveWorking" when changed.
        Parameters:
        w - true permissive, false NOT permissive

      • setBlockSpeedName

        public void setBlockSpeedName​(java.lang.String s)
        Set the Block Speed Name.

        Does not perform name validity checking. Does not send Property Change Event.

        Parameters:
        s - new Speed Name String.

      • setBlockSpeed

        public void setBlockSpeed​(java.lang.String s)
                   throws JmriException
        Set the Block Speed, preferred method.

        Fires propertyChange "BlockSpeedChange" when changed.

        Parameters:
        s - Speed String
        Throws:
        JmriException - if Value of requested block speed is not valid.

      • setCurvature

        public void setCurvature​(int c)
        Set Block Curvature Constant. Valid values : Block.NONE, Block.GRADUAL, Block.TIGHT, Block.SEVERE Fires propertyChange "BlockCurvatureChange" when changed.
        Parameters:
        c - Constant, e.g. Block.GRADUAL

      • getCurvature

        public int getCurvature()
        Get Block Curvature Constant. Defaults to Block.NONE
        Returns:
        constant, e.g. Block.TIGHT

      • setLength

        public void setLength​(float l)
        Set length in millimeters. Paths will inherit this length, if their length is not specifically set. This length is the maximum length of any Path in the block. Path lengths exceeding this will be set to the default length.

        Fires propertyChange "BlockLengthChange" when changed, float values in mm.

        Parameters:
        l - length in millimeters

      • getLengthMm

        public float getLengthMm()
        Get Block Length in Millimetres. Default 0.0f.
        Returns:
        length in mm.

      • getLengthCm

        public float getLengthCm()
        Get Block Length in Centimetres. Courtesy method using result from getLengthMm.
        Returns:
        length in centimetres.

      • getLengthIn

        public float getLengthIn()
        Get Block Length in Inches. Courtesy method using result from getLengthMm.
        Returns:
        length in inches.

      • equals

        public boolean equals​(java.lang.Object obj)
        Note: this has to make choices about identity values (always the same) and operation values (can change as the block works). Might be missing some identity values.
        Overrides:
        equals in class AbstractNamedBean
        Parameters:
        obj - the reference object with which to compare.
        Returns:
        true if this object is the same as the obj argument; false otherwise.

      • handleSensorChange

        void handleSensorChange​(java.beans.PropertyChangeEvent e)
        Handle change in sensor state.

        Defers real work to goingActive, goingInactive methods.

        Parameters:
        e - the event

      • handleReporterChange

        void handleReporterChange​(java.beans.PropertyChangeEvent e)
        Handle change in Reporter value.
        Parameters:
        e - PropertyChangeEvent

      • goingInactive

        public void goingInactive()
        Handles Block sensor going INACTIVE: this block is empty

      • goingActive

        public void goingActive()
        Handles Block sensor going ACTIVE: this block is now occupied, figure out from who and copy their value.

      • findFromPath

        public Path findFromPath()
        Find which path this Block became Active, without actually modifying the state of this block.

        (this is largely a copy of the 'Search' part of the logic from goingActive())

        Returns:
        the next path

      • setAllocated

        public void setAllocated​(java.lang.Boolean boo)
        This allows the layout block to inform any listeners to the block that the higher level layout block has been set to "useExtraColor" which is an indication that it has been allocated to a section by the AutoDispatcher. The value set is not retained in any form by the block, it is purely to trigger a propertyChangeEvent.
        Parameters:
        boo - Allocation status

      • getLocoAddress

        public LocoAddress getLocoAddress​(java.lang.String rep)
        Parse a given string and return the LocoAddress value that is presumed stored within it based on this object's protocol. The Class Block implementation defers to its associated Reporter, if it exists.
        Specified by:
        getLocoAddress in interface PhysicalLocationReporter
        Parameters:
        rep - String to be parsed
        Returns:
        LocoAddress address parsed from string, or null if this Block isn't associated with a Reporter, or is associated with a Reporter that is not also a PhysicalLocationReporter

      • getDirection

        public PhysicalLocationReporter.Direction getDirection​(java.lang.String rep)
        Parses out a (possibly old) LnReporter-generated report string to extract the direction from within it based on this object's protocol. The Class Block implementation defers to its associated Reporter, if it exists.
        Specified by:
        getDirection in interface PhysicalLocationReporter
        Parameters:
        rep - String to be parsed
        Returns:
        PhysicalLocationReporter.Direction direction parsed from string, or null if this Block isn't associated with a Reporter, or is associated with a Reporter that is not also a PhysicalLocationReporter

      • getPhysicalLocation

        public PhysicalLocation getPhysicalLocation​(java.lang.String s)
        Return this Block's physical location, if it exists. Does not use the parameter s. Defers actual work to the helper methods in class PhysicalLocation
        Specified by:
        getPhysicalLocation in interface PhysicalLocationReporter
        Parameters:
        s - (this parameter is ignored)
        Returns:
        PhysicalLocation : this Block's location.

      • getBeanType

        public java.lang.String getBeanType()
        Description copied from interface: NamedBean
        For instances in the code where we are dealing with just a bean and a message needs to be passed to the user or in a log.
        Specified by:
        getBeanType in interface NamedBean
        Returns:
        a string of the bean type, eg Turnout, Sensor etc