Data update

Task/Rendezvous/Java/rendezvous.java

@@ -0,0 +1,96 @@
+import java.io.PrintStream;
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Optional;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
+import java.util.function.Supplier;
+
+public final class Rendezvous {
+
+	public static void main(String[] args) throws InterruptedException, ExecutionException {		
+		List<String> motherGooseText = List.of( "Old Mother Goose,",
+				  								"When she wanted to wander,",
+				  								"Would ride through the air,",
+				  								"On a very fine gander.",
+				  								"Jack's mother came in,",
+				  								"And caught the goose soon,",
+				  								"And mounting its back,",
+				  								"Flew up to the moon." );
+		
+		List<String> humptyDumptyText = List.of( "Humpty Dumpty sat on a wall.",
+				     							 "Humpty Dumpty had a great fall.",
+				     							 "All the king's horses and all the king's men,",
+				     							 "Couldn't put Humpty together again." );
+		
+		Printer reserve = new Printer("Reserve", Optional.empty(), System.out);
+		Printer main = new Printer("Main", Optional.of(reserve), System.out);
+				
+		Messenger motherGoose = new Messenger(motherGooseText, main);
+		Messenger humptyDumpty = new Messenger(humptyDumptyText, main);
+		
+		while ( CompletableFuture.supplyAsync(motherGoose).get() |
+				CompletableFuture.supplyAsync(humptyDumpty).get() ) { }
+	}
+
+}
+
+final class Messenger implements Supplier<Boolean> {
+	
+    public Messenger(List<String> aMessage, Printer aPrinter) {
+    	message = new ArrayList<String>(aMessage);
+    	iterator = message.iterator();
+        printer = aPrinter;
+    }
+
+    @Override
+	public Boolean get() {
+		if ( iterator.hasNext() ) {
+			try {
+				printer.display(iterator.next());
+			} catch (OutOfInkException exception) {
+				return false;
+			}
+			return true;
+		}	
+		return false;
+	}
+
+    private List<String> message;
+	private Iterator<String> iterator;
+    private Printer printer;
+
+}
+
+final class Printer {	
+	
+    public Printer(String aName, Optional<Printer> aReserve, PrintStream aPrintStream) {
+        name = aName;
+        reserve = aReserve;
+        printStream = aPrintStream;
+    }
+
+    public void display(String message) throws OutOfInkException {
+    	if ( inkLevelForClientUse > 0 ) {
+    		printStream.println("(" + name + ") " + message);
+    		inkLevelForClientUse -= 1;
+    	} else {
+    		if ( reserve.isPresent() ) {
+    			reserve.get().display(message);
+    		} else {
+    			printStream.println("        Printer out of ink");	
+    			throw new OutOfInkException();
+    		}
+    	}
+    	
+    }
+
+    private String name;
+    private Optional<Printer> reserve;
+    private PrintStream printStream;
+    private int inkLevelForClientUse = 5;
+
+}
+
+final class OutOfInkException extends Exception { }