java中的内部类

public class TestA {class A{public long a;}class B extends A{public long b;}void seta(A data[],int i){data[i].a = 2;}public static void main(String args[]){TestA aTestA = new TestA();B data[] = new B[4]; //对象数组B b1 = aTestA.new B(); //声明一个内部类对象B b2 = aTestA.new B();B b3 = aTestA.new B();B b4 = aTestA.new B();data[0] = b1;data[1] = b2;data[2] = b3;data[3] = b4;for(int i =0;i<4;i++){data[i].a = 1;data[i].b = 1;aTestA.seta(data,i); //继承中的向上转型，父类引用指向子类对象}for(int i=0;i<4;++i){System.out.println(data[i].a+"and"+data[i].b);}}}