[20-05-17][Thinking in Java 24]Java Inner Class 8 - Anonymous Inner Class 3

 1 package test_15_3;
 2 
 3 public abstract class Base {
 4 
 5     public Base(int i) {
 6         System.out.println("Base constructor, i = " + i);
 7     }
 8     
 9     public abstract void f();
10 }

 1 package test_15_3;
 2 
 3 public class AnonymousConstructor {
 4     
 5     public static Base getBase(int i) {
 6         // 变量i不一定是final的，因为i被传递给匿名类的基类的构造器，并不会在匿名内部类中直接使用
 7         return new Base(i) {
 8             // 通过实例初始化，达到为匿名内部类创建一个构造器的效果
 9             {
10                 System.out.println("Inside instance initializer");
11             }
12 
13             @Override
14             public void f() {
15                 System.out.println("In anonymous f()");
16             }
17         };
18     }
19     
20     public static void main(String[] args) {
21         
22         Base base = getBase(10);
23         base.f();
24     }
25 }

结果如下：

Base constructor, i = 10
Inside instance initializer
In anonymous f()