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);
		}
		
	}

}