为什么我这里的outer.this.b会被eclipse报错？

package com.imooc;

public class HelloWorld{

private int b = 8;

protected class HelloChina{

int b = 7;

public void show() {

System.out.println("访问外部类中的a："+ Outer.this.b);

System.out.print("访问内部类中的b:" + b);

}

}

public static void main(String []args) {

HelloWorld hello = new HelloWorld();

HelloChina china = hello.new HelloChina();

china.show();

}

}