////////////////////////////////////////////////////////////////////////
//
// Description:
//
// Internet: http://bioinformatik.gloomit.de
//
// Copyright (C) 2006 Phillip Kroll
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
////////////////////////////////////////////////////////////////////////


/*------------------------------------------------------------------------
 	Klasse: MainClass, Hauptprogramm
------------------------------------------------------------------------*/

public class MainClass {
	
	public static void main(String[] args) {
		
		// eine Bahnstrecke erstellen, und die 
		// Fahrtzeit übergeben
		Bahnstrecke bahnstrecke = new Bahnstrecke( 0 );
		
		// Anzahl der Züge die erstellt werden sollen
		int trains = 100;
		
		// Züge erstellen und auf die Bahnstrecke schicken
		for ( int i = 0; i < trains; i++ ){
			new Zug( bahnstrecke, "ZUG" + ( i + 1000 ) );
		}
		
		
	}
}





/*------------------------------------------------------------------------
 	Klasse: Bahnstrecke, Thread Synchronisierung
------------------------------------------------------------------------*/

public class Bahnstrecke {

	private int EastTrains = 0;
	private int WestTrains = 0;
	private int TravelTime = 3;
	private int EastMax = 3;
	private int WestMax = 3;

	
	public Bahnstrecke( int TravelTime ){
		this.TravelTime = TravelTime;
	}
	
	// Neuen Zug richtung Osten registrieren.
	// Falls Züge richtung Westen unterwegs sind oder die maximale
	// Anzahl an Zügen die Richtung Osten fahren erreicht ist, wird
	// der Zug-Thread auf warten gesetzt
	public synchronized void GoEast( Zug train ){

		while( ( WestTrains > 0 ) | ( EastTrains >= EastMax ) ){
			try { wait(); }
			catch( InterruptedException e){}
		}
		EastTrains++;

		System.out.println( train.GetSerialNumber() + " goes East. " +
							GetRailwayStatus());
		
	}
		
	// Neuen Zug richtung Westen registrieren.
	// Falls Züge richtung Osten unterwegs sind oder die maximale
	// Anzahl an Zügen die Richtung Westen fahren erreicht ist, wird
	// der Zug-Thread auf warten gesetzt
	public synchronized void GoWest( Zug train ){

		while( ( EastTrains > 0 ) | ( WestTrains >= WestMax ) ){
			try { wait(); }
			catch( InterruptedException e){}
		}
		WestTrains++;

		System.out.println( train.GetSerialNumber() + " goes West. " +
							GetRailwayStatus() );
		
	}
	
	// Bahnstrecke im Osten verlassen
	public synchronized void LeaveToTheEast( Zug train ){
		
		notifyAll();
		if ( EastTrains > 0 ) EastTrains--;
	
		System.out.println( train.GetSerialNumber() + " left East. "  +
							GetRailwayStatus());
		
	}
	
	// Bahnstrecke im Westen verlassen
	public synchronized void LeaveToTheWest( Zug train ){
		
		notifyAll();
		if ( WestTrains > 0 ) WestTrains--;
		
		System.out.println( train.GetSerialNumber() + " left West. " + 
				GetRailwayStatus());			
		
	}
		
	public int GetTravelTime(){
		return TravelTime;
	}

	// Status String für die Bahnstrecke erstellen
	public String GetRailwayStatus(){
		return ( "(East Trains: " + EastTrains + 
			 " West Trains: " + WestTrains + ")" );
	}
	
}



/*------------------------------------------------------------------------
 	Klasse: Zug, Thread
------------------------------------------------------------------------*/

public class Zug extends Thread{
	
	private Bahnstrecke bahnstrecke;
	private String SerialNumber;
	
	public Zug( Bahnstrecke bahnstrecke, String SerialNumber ){
		this.bahnstrecke = bahnstrecke;
		this.SerialNumber = SerialNumber;
		start();
	}
	
	public String GetSerialNumber(){
		return SerialNumber;
	}
	
	
	public void run(){
		
		// Zug soll zufällig nach Osten oder Westen fahren
		if ( (int)( Math.random() + 0.5 ) == 1 ){
			
			// Fahrt nach Osten
			bahnstrecke.GoEast( this );
			
			// Fahr druch sleep simulieren
			try { sleep( bahnstrecke.GetTravelTime() * 1000 ); } 
			catch ( InterruptedException E ) {}
			
			// Bahnstrecke nach Osten verlassen
			bahnstrecke.LeaveToTheEast( this );
			

		} else {
			
			// Fahrt nach Westen
			bahnstrecke.GoWest( this );

			// Fahr druch sleep simulieren
			try { sleep( bahnstrecke.GetTravelTime() * 1000 ); } 
			catch ( InterruptedException E ) {}
			
			// Bahnstrecke nach Westen verlassen
			bahnstrecke.LeaveToTheWest( this );
			

			
		}
			
		
		
	}

}


/* Beispeil für Programmausgabe, 100 Züge


ZUG1000 goes East. (East Trains: 1 West Trains: 0)
ZUG1000 left East. (East Trains: 0 West Trains: 0)
ZUG1001 goes West. (East Trains: 0 West Trains: 1)
ZUG1003 goes West. (East Trains: 0 West Trains: 2)
ZUG1005 goes West. (East Trains: 0 West Trains: 3)
ZUG1001 left West. (East Trains: 0 West Trains: 2)
ZUG1006 goes West. (East Trains: 0 West Trains: 3)
ZUG1003 left West. (East Trains: 0 West Trains: 2)
ZUG1005 left West. (East Trains: 0 West Trains: 1)
ZUG1009 goes West. (East Trains: 0 West Trains: 2)
ZUG1010 goes West. (East Trains: 0 West Trains: 3)
ZUG1006 left West. (East Trains: 0 West Trains: 2)
ZUG1015 goes West. (East Trains: 0 West Trains: 3)
ZUG1009 left West. (East Trains: 0 West Trains: 2)
ZUG1016 goes West. (East Trains: 0 West Trains: 3)
ZUG1010 left West. (East Trains: 0 West Trains: 2)
ZUG1015 left West. (East Trains: 0 West Trains: 1)
ZUG1065 goes West. (East Trains: 0 West Trains: 2)
ZUG1016 left West. (East Trains: 0 West Trains: 1)
ZUG1017 goes West. (East Trains: 0 West Trains: 2)
ZUG1018 goes West. (East Trains: 0 West Trains: 3)
ZUG1065 left West. (East Trains: 0 West Trains: 2)
ZUG1017 left West. (East Trains: 0 West Trains: 1)
ZUG1018 left West. (East Trains: 0 West Trains: 0)
ZUG1014 goes East. (East Trains: 1 West Trains: 0)
ZUG1021 goes East. (East Trains: 2 West Trains: 0)
ZUG1022 goes East. (East Trains: 3 West Trains: 0)
ZUG1014 left East. (East Trains: 2 West Trains: 0)
ZUG1023 goes East. (East Trains: 3 West Trains: 0)
ZUG1021 left East. (East Trains: 2 West Trains: 0)
ZUG1022 left East. (East Trains: 1 West Trains: 0)
ZUG1023 left East. (East Trains: 0 West Trains: 0)
ZUG1019 goes West. (East Trains: 0 West Trains: 1)
ZUG1020 goes West. (East Trains: 0 West Trains: 2)
ZUG1024 goes West. (East Trains: 0 West Trains: 3)
ZUG1019 left West. (East Trains: 0 West Trains: 2)
ZUG1020 left West. (East Trains: 0 West Trains: 1)
ZUG1024 left West. (East Trains: 0 West Trains: 0)
ZUG1025 goes East. (East Trains: 1 West Trains: 0)
ZUG1027 goes East. (East Trains: 2 West Trains: 0)
ZUG1032 goes East. (East Trains: 3 West Trains: 0)
ZUG1025 left East. (East Trains: 2 West Trains: 0)
ZUG1034 goes East. (East Trains: 3 West Trains: 0)
ZUG1027 left East. (East Trains: 2 West Trains: 0)
ZUG1032 left East. (East Trains: 1 West Trains: 0)
ZUG1034 left East. (East Trains: 0 West Trains: 0)
ZUG1026 goes West. (East Trains: 0 West Trains: 1)
ZUG1028 goes West. (East Trains: 0 West Trains: 2)
ZUG1029 goes West. (East Trains: 0 West Trains: 3)
ZUG1026 left West. (East Trains: 0 West Trains: 2)
ZUG1028 left West. (East Trains: 0 West Trains: 1)
ZUG1029 left West. (East Trains: 0 West Trains: 0)
ZUG1030 goes West. (East Trains: 0 West Trains: 1)
ZUG1031 goes West. (East Trains: 0 West Trains: 2)
ZUG1033 goes West. (East Trains: 0 West Trains: 3)
ZUG1030 left West. (East Trains: 0 West Trains: 2)
ZUG1031 left West. (East Trains: 0 West Trains: 1)
ZUG1033 left West. (East Trains: 0 West Trains: 0)
ZUG1035 goes West. (East Trains: 0 West Trains: 1)
ZUG1036 goes West. (East Trains: 0 West Trains: 2)
ZUG1040 goes West. (East Trains: 0 West Trains: 3)
ZUG1035 left West. (East Trains: 0 West Trains: 2)
ZUG1036 left West. (East Trains: 0 West Trains: 1)
ZUG1040 left West. (East Trains: 0 West Trains: 0)
ZUG1037 goes East. (East Trains: 1 West Trains: 0)
ZUG1038 goes East. (East Trains: 2 West Trains: 0)
ZUG1039 goes East. (East Trains: 3 West Trains: 0)
ZUG1037 left East. (East Trains: 2 West Trains: 0)
ZUG1038 left East. (East Trains: 1 West Trains: 0)
ZUG1039 left East. (East Trains: 0 West Trains: 0)
ZUG1041 goes East. (East Trains: 1 West Trains: 0)
ZUG1042 goes East. (East Trains: 2 West Trains: 0)
ZUG1045 goes East. (East Trains: 3 West Trains: 0)
ZUG1041 left East. (East Trains: 2 West Trains: 0)
ZUG1042 left East. (East Trains: 1 West Trains: 0)
ZUG1045 left East. (East Trains: 0 West Trains: 0)
ZUG1043 goes West. (East Trains: 0 West Trains: 1)
ZUG1044 goes West. (East Trains: 0 West Trains: 2)
ZUG1046 goes West. (East Trains: 0 West Trains: 3)
ZUG1043 left West. (East Trains: 0 West Trains: 2)
ZUG1044 left West. (East Trains: 0 West Trains: 1)
ZUG1046 left West. (East Trains: 0 West Trains: 0)
ZUG1047 goes East. (East Trains: 1 West Trains: 0)
ZUG1051 goes East. (East Trains: 2 West Trains: 0)
ZUG1054 goes East. (East Trains: 3 West Trains: 0)
ZUG1047 left East. (East Trains: 2 West Trains: 0)
ZUG1051 left East. (East Trains: 1 West Trains: 0)
ZUG1054 left East. (East Trains: 0 West Trains: 0)
ZUG1048 goes West. (East Trains: 0 West Trains: 1)
ZUG1049 goes West. (East Trains: 0 West Trains: 2)
ZUG1050 goes West. (East Trains: 0 West Trains: 3)
ZUG1048 left West. (East Trains: 0 West Trains: 2)
ZUG1049 left West. (East Trains: 0 West Trains: 1)
ZUG1050 left West. (East Trains: 0 West Trains: 0)
ZUG1052 goes West. (East Trains: 0 West Trains: 1)
ZUG1053 goes West. (East Trains: 0 West Trains: 2)
ZUG1055 goes West. (East Trains: 0 West Trains: 3)
ZUG1052 left West. (East Trains: 0 West Trains: 2)
ZUG1053 left West. (East Trains: 0 West Trains: 1)
ZUG1055 left West. (East Trains: 0 West Trains: 0)
ZUG1056 goes East. (East Trains: 1 West Trains: 0)
ZUG1060 goes East. (East Trains: 2 West Trains: 0)
ZUG1061 goes East. (East Trains: 3 West Trains: 0)
ZUG1056 left East. (East Trains: 2 West Trains: 0)
ZUG1060 left East. (East Trains: 1 West Trains: 0)
ZUG1061 left East. (East Trains: 0 West Trains: 0)
ZUG1057 goes West. (East Trains: 0 West Trains: 1)
ZUG1058 goes West. (East Trains: 0 West Trains: 2)
ZUG1059 goes West. (East Trains: 0 West Trains: 3)
ZUG1057 left West. (East Trains: 0 West Trains: 2)
ZUG1058 left West. (East Trains: 0 West Trains: 1)
ZUG1059 left West. (East Trains: 0 West Trains: 0)
ZUG1062 goes East. (East Trains: 1 West Trains: 0)
ZUG1066 goes East. (East Trains: 2 West Trains: 0)
ZUG1068 goes East. (East Trains: 3 West Trains: 0)
ZUG1062 left East. (East Trains: 2 West Trains: 0)
ZUG1066 left East. (East Trains: 1 West Trains: 0)
ZUG1068 left East. (East Trains: 0 West Trains: 0)
ZUG1064 goes West. (East Trains: 0 West Trains: 1)
ZUG1067 goes West. (East Trains: 0 West Trains: 2)
ZUG1069 goes West. (East Trains: 0 West Trains: 3)
ZUG1064 left West. (East Trains: 0 West Trains: 2)
ZUG1067 left West. (East Trains: 0 West Trains: 1)
ZUG1069 left West. (East Trains: 0 West Trains: 0)
ZUG1070 goes East. (East Trains: 1 West Trains: 0)
ZUG1073 goes East. (East Trains: 2 West Trains: 0)
ZUG1075 goes East. (East Trains: 3 West Trains: 0)
ZUG1070 left East. (East Trains: 2 West Trains: 0)
ZUG1073 left East. (East Trains: 1 West Trains: 0)
ZUG1075 left East. (East Trains: 0 West Trains: 0)
ZUG1071 goes West. (East Trains: 0 West Trains: 1)
ZUG1072 goes West. (East Trains: 0 West Trains: 2)
ZUG1074 goes West. (East Trains: 0 West Trains: 3)
ZUG1071 left West. (East Trains: 0 West Trains: 2)
ZUG1072 left West. (East Trains: 0 West Trains: 1)
ZUG1074 left West. (East Trains: 0 West Trains: 0)
ZUG1076 goes East. (East Trains: 1 West Trains: 0)
ZUG1077 goes East. (East Trains: 2 West Trains: 0)
ZUG1080 goes East. (East Trains: 3 West Trains: 0)
ZUG1076 left East. (East Trains: 2 West Trains: 0)
ZUG1077 left East. (East Trains: 1 West Trains: 0)
ZUG1080 left East. (East Trains: 0 West Trains: 0)
ZUG1078 goes West. (East Trains: 0 West Trains: 1)
ZUG1079 goes West. (East Trains: 0 West Trains: 2)
ZUG1081 goes West. (East Trains: 0 West Trains: 3)
ZUG1078 left West. (East Trains: 0 West Trains: 2)
ZUG1079 left West. (East Trains: 0 West Trains: 1)
ZUG1081 left West. (East Trains: 0 West Trains: 0)
ZUG1082 goes East. (East Trains: 1 West Trains: 0)
ZUG1083 goes East. (East Trains: 2 West Trains: 0)
ZUG1084 goes East. (East Trains: 3 West Trains: 0)
ZUG1082 left East. (East Trains: 2 West Trains: 0)
ZUG1083 left East. (East Trains: 1 West Trains: 0)
ZUG1084 left East. (East Trains: 0 West Trains: 0)
ZUG1085 goes East. (East Trains: 1 West Trains: 0)
ZUG1086 goes East. (East Trains: 2 West Trains: 0)
ZUG1087 goes East. (East Trains: 3 West Trains: 0)
ZUG1085 left East. (East Trains: 2 West Trains: 0)
ZUG1086 left East. (East Trains: 1 West Trains: 0)
ZUG1087 left East. (East Trains: 0 West Trains: 0)
ZUG1088 goes West. (East Trains: 0 West Trains: 1)
ZUG1090 goes West. (East Trains: 0 West Trains: 2)
ZUG1092 goes West. (East Trains: 0 West Trains: 3)
ZUG1088 left West. (East Trains: 0 West Trains: 2)
ZUG1090 left West. (East Trains: 0 West Trains: 1)
ZUG1092 left West. (East Trains: 0 West Trains: 0)
ZUG1089 goes East. (East Trains: 1 West Trains: 0)
ZUG1091 goes East. (East Trains: 2 West Trains: 0)
ZUG1093 goes East. (East Trains: 3 West Trains: 0)
ZUG1089 left East. (East Trains: 2 West Trains: 0)
ZUG1091 left East. (East Trains: 1 West Trains: 0)
ZUG1093 left East. (East Trains: 0 West Trains: 0)
ZUG1097 goes West. (East Trains: 0 West Trains: 1)
ZUG1099 goes West. (East Trains: 0 West Trains: 2)
ZUG1011 goes West. (East Trains: 0 West Trains: 3)
ZUG1097 left West. (East Trains: 0 West Trains: 2)
ZUG1099 left West. (East Trains: 0 West Trains: 1)
ZUG1011 left West. (East Trains: 0 West Trains: 0)
ZUG1098 goes East. (East Trains: 1 West Trains: 0)
ZUG1012 goes East. (East Trains: 2 West Trains: 0)
ZUG1002 goes East. (East Trains: 3 West Trains: 0)
ZUG1098 left East. (East Trains: 2 West Trains: 0)
ZUG1012 left East. (East Trains: 1 West Trains: 0)
ZUG1002 left East. (East Trains: 0 West Trains: 0)
ZUG1004 goes East. (East Trains: 1 West Trains: 0)
ZUG1007 goes East. (East Trains: 2 West Trains: 0)
ZUG1063 goes East. (East Trains: 3 West Trains: 0)
ZUG1004 left East. (East Trains: 2 West Trains: 0)
ZUG1007 left East. (East Trains: 1 West Trains: 0)
ZUG1095 goes East. (East Trains: 2 West Trains: 0)
ZUG1096 goes East. (East Trains: 3 West Trains: 0)
ZUG1063 left East. (East Trains: 2 West Trains: 0)
ZUG1008 goes East. (East Trains: 3 West Trains: 0)
ZUG1095 left East. (East Trains: 2 West Trains: 0)
ZUG1096 left East. (East Trains: 1 West Trains: 0)
ZUG1013 goes East. (East Trains: 2 West Trains: 0)
ZUG1008 left East. (East Trains: 1 West Trains: 0)
ZUG1013 left East. (East Trains: 0 West Trains: 0)
ZUG1094 goes West. (East Trains: 0 West Trains: 1)
ZUG1094 left West. (East Trains: 0 West Trains: 0)