素人がGenericsを使おうとしたさんぷる

sample.java

package sample;

public class HogeClient {
	private Adapter adapter;
	private static Class<? extends Adapter> staticAdapter;

	public Adapter getAdaper() {
		if ( staticAdapter != null){
			try {
				this.adapter = staticAdapter.newInstance();
			} catch (InstantiationException | IllegalAccessException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}else if ( null == adapter){
			this.adapter = new Adapter();
		}
		return adapter;
	}
	
	public static void setAdapter(Class<? extends Adapter> declaredAdapter){
		staticAdapter = declaredAdapter;
	}
	
	public void talk(){
		this.getAdaper().say();
	}
}