class Outer{
    private int size;
    
    class Inner{
        void doSuff(){
            size++;
            System.out.println("The size value of the Outer class: " + size);
        }
    }
}

public class TestInner {
    public static void main(String[] a) {
        Outer out = new Outer();
        Outer.Inner in = out.new Inner();//声明并创建内部类对象
        in.doSuff();
    }
}