「プログラム2-1」

public interface KeyValueWriter{
	public void initialize();
	public void write(String key, String value);
	public void complete();
}


「プログラム2-2」

public class ToTags implements KeyValueWriter{
	public void initialize(){
		System.out.println("<data>");
	}
	public void write(String key, String value){
		System.out.println("<entry key=\"" + key + "\">"
						 + value + "</entry>");
	}
	public void complete(){
		System.out.println("</data>");
	}
}


「プログラム2-3」

public class KeyValueWriterAdapter implements KeyValueWriter{
	public void initialize(){}
	public void write(String key, String value){};
	public void complete(){}
}


「プログラム2-4」

public class ToProperties extends KeyValueWriterAdapter{
	public void write(String key, String value){
		System.out.println(key + "=" + value);
	}
}

「プログラム2-5」

public class Test2{
	static String[][] pairs = { {"width", "200"},
								{"height", "120"},
								{"color", "blue"} };
	public static void main(String[] args){
		write(new ToProperties());
		System.out.println("---------------");
		write(new ToTags());
	}
	private static void write(KeyValueWriter out){
		out.initialize();
		for(String[] pair: pairs){
			out.write(pair[0], pair[1]);
		}
		out.complete();
	}
}