package asia;

class bbb
{
String capital;
public void bbb()
{
capital=new String("Beijing");
}
public String getCapital()
{
return capital;
}
}
class aaa extends bbb
{

bbb b=new bbb();
public String getCapital()
{
return b.capital;
}
public static void main(String args[])
{
aaa a=new aaa();
System.out.println(a.getCapital());
}
}


为什么输出结果是null

class bbb
{
String capital;
//构造方法不带void
public bbb()
{
capital=new String("Beijing");
}
public String getCapital()
{
return capital;
}
}
class aaa extends bbb
{

bbb b=new bbb();
public String getCapital()
{
return b.capital;
}
public static void main(String args[])
{
aaa a=new aaa();
System.out.println(a.getCapital());
}
}

谢谢各位