updating Singleton with enum example, Template Method with list example

src/headfirst/designpatterns/singleton/enumS/Singleton.java

@@ -0,0 +1,12 @@
+package headfirst.designpatterns.singleton.enumS;
+
+public enum Singleton {
+	UNIQUE_INSTANCE;
+
+	// other useful fields here
+
+	// other useful methods here
+	public String getDescription() {
+		return "I'm a thread safe Singleton!";
+	}
+}

src/headfirst/designpatterns/singleton/enumS/SingletonClient.java

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+package headfirst.designpatterns.singleton.enumS;
+
+public class SingletonClient {
+	public static void main(String[] args) {
+		Singleton singleton = Singleton.UNIQUE_INSTANCE;
+		System.out.println(singleton.getDescription());
+	}
+}

src/headfirst/designpatterns/templatemethod/list/MyListTestDrive.java

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+package headfirst.designpatterns.templatemethod.list;
+
+import java.util.List;
+
+public class MyListTestDrive {
+
+	public static void main(String[] args) {
+		String[] ducks = { "Mallard Duck", "Redhead Duck", "Rubber Duck", "Decoy Duck"};
+		MyStringList ducksList = new MyStringList(ducks);
+		for (int i = 0; i < ducksList.size(); i++) {
+			System.out.println(ducksList.get(i));
+		}
+		String oldDuck = ducksList.set(3, "Donald Duck");
+		System.out.println("Replacing " + oldDuck);
+		System.out.println("New List:");
+		for (int i = 0; i < ducksList.size(); i++) {
+			System.out.println(ducksList.get(i));
+		}
+		// Now the real test... subList()
+		List ducksSubList = ducksList.subList(2, 3);
+		System.out.println("Created a sub list of ducks, with size: " + ducksSubList.size());
+		for (int i = 0; i < ducksSubList.size(); i++) {
+			System.out.println(ducksSubList.get(i));
+		}
+	}
+}

src/headfirst/designpatterns/templatemethod/list/MyStringList.java

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+package headfirst.designpatterns.templatemethod.list;
+
+import java.util.AbstractList;
+
+// AbstractList provides a skeletal implementation of the List interface 
+// to minimize the effort required to implement this interface backed by 
+// a "random access" data store (such as an array). 
+
+// To implement an unmodifiable list, the programmer needs only to extend 
+// this class and provide implementations for the get(int) and size() methods.
+// get(int index) is an abstract method in AbstractList
+// size() is an abstract method in AbstractCollection
+// subList(int fromIndex, int toIndex) returns a view of the portion of this list 
+// between the specified fromIndex, inclusive, and toIndex, exclusive.
+
+public class MyStringList extends AbstractList<String> {
+	private String[] myList;
+	MyStringList(String[] strings) {
+		myList = strings;
+	}
+	@Override
+	public String get(int index) {
+		return myList[index];
+	}
+	@Override
+	public String set(int index, String item) {
+		String oldString = myList[index];
+		myList[index] = item;
+		return oldString;
+	}
+	@Override
+	public int size() {
+		return myList.length;
+	}
+}