Thinking In Java 原文章

				// interfaces/Ex2.java
				// TIJ4 Chapter Interfaces, Exercise 2, page 315
				// Create a class as abstract without including any abstract methods, and verify
				// that you cannot create any instances of that class.
				
				abstract class Nogo1 {
					Nogo1() { System.out.println("Nogo1()"); }
				}
				
				abstract class Nogo2 {}
				
				class Go1 extends Nogo1 {
					Go1() { System.out.println("Go1()"); }
				}
				
				public class Ex2 {
					public static void main(String[] args) {
						// Nogo1 and Nogo2 cannot be instantiated:
						// Nogo1 ng1 = new Nogo1();
						// Nogo2 ng2 = new Nogo2();
						// But Nogo1() constructor called during instatiation of child: 	
						Go1 g1 = new Go1();
					}
				}