내부 클래스 과부하

package test.object;

public class Base {

	private String baseName = "base";
	
	public Base() {
		callName();
	}
	
	public void callName() {
		System.out.println(baseName);
	}
	
	static class Sub extends Base {
		private String baseName = "sub";
		
		public void callName() {
			System.out.println(baseName);
		}
	}
	
	public static void main(String[] args) {
		//                   ，
		Base base = new Sub();//null
	}
}