class X{……} x;class Y :X {} y;

class X{……} x;class Y :X {} y; class Point{ private double x; private double y; Point(doubl class Point{ protected int x,y; public Point(){} public Poin class Point{ public double x,y; Point(double x,double y){ th java语句class Bird{int x,y; void fly(int x, int y) {this.x=x; java public class Z extens X｛ Y y＝new Y 类定义为什么要这样class point{public:double x,y;point(){};point(doubl 已知有如下类的定义:public class Point { private double x,y; public Po #include class base { Private:int x,y; public:void setxy(int 搞不懂 求解释~~class A{ int x=0,y=0; A(int x,int y){ this.x=x;this {(x,y) |x|+|y| x>y?x:y