added ex J

src/exercises/ex_j/Diner.java

@@ -0,0 +1,33 @@
+package exercises.ex_j;
+
+class Diner {
+    private String name;
+    private boolean isHungry;
+
+    public Diner(String name) {
+        this.name = name;
+        isHungry = true;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public boolean isHungry() {
+        return isHungry;
+    }
+
+    public void eatWith(Spoon spoon, Diner spouse) {
+        while (isHungry) {
+            if (spoon.getOwner() == this) {
+                if (spouse.isHungry()) {
+                    System.out.println(getName() + ": You eat first my darling " + spouse.getName() + "!");
+                    spoon.setOwner(spouse);
+                } else {
+                    spoon.use();
+                    this.isHungry = false;
+                }
+            }
+        }
+    }
+}

src/exercises/ex_j/LivelockDinner.java

@@ -0,0 +1,20 @@
+package exercises.ex_j;
+
+public class LivelockDinner {
+    public static void main(String[] args) {
+        final Diner husband = new Diner("Bob");
+        final Diner wife = new Diner("Alice");
+        final Spoon spoon = new Spoon(husband);
+
+        new Thread(new Runnable() {
+            public void run() {
+                husband.eatWith(spoon, wife);
+            }
+        }).start();
+        new Thread(new Runnable() {
+            public void run() {
+                wife.eatWith(spoon, husband);
+            }
+        }).start();
+    }
+}

src/exercises/ex_j/Spoon.java

@@ -0,0 +1,21 @@
+package exercises.ex_j;
+
+class Spoon {
+    private Diner owner;
+
+    public synchronized Diner getOwner() {
+        return owner;
+    }
+
+    public Spoon(Diner d) {
+        owner = d;
+    }
+
+    public synchronized void setOwner(Diner d) {
+        owner = d;
+    }
+
+    public synchronized void use() {
+        System.out.printf("%s has eaten!", owner.getName());
+    }
+}