JAVA:定义类与子类的表示下面关系,父类POINT(点) 子类Rectangle

JAVA:定义类与子类的表示下面关系,父类POINT(点) 子类Rectangle(属性左上角,长和宽)子类cube的代码,还有测试函数 我没时间了!!

class Base{
Base(){

}
public void m(){

}
}
class Sub extends Base{

Sub(){
super(); //调用父类的构造方法
super.m();//调用父类的方法
}
public void n(){

}
public static void main(String[] args){
Sub s = new Sub();
s.m();//这里应该理解为：
子类继承了父类，那么这个m()应该属于子类的了！，所以我们在重写的时候要覆盖父类的方法！ 那么这里算调用子类自己的方法了
Base b = new Base();
b.m();//父类对象调用自己方法
//b.n();编译错误，因为子类的方法对父类不可见！
}
}

父类调用子类的方法 只能是在 父类里构造子类的对象，通过对象来调用！
如果子类的是静态方法，那么直接拿类调用！

子类调用父类的方法 用 super.methodName(); 只能在非静态方法
里这样调用

补充：
就是 在 Base 类里
Sub s = new Sub();
s.n();

public class TestClass { public static void main(String[] args) { Point p = new Point(); Rectangle r = new Rectangle(); Cube c = new Cube(); r.setLen("30"); System.out.println(r.getLen()); } } class Point { public Point() { System.out.println("Point Class"); } } class Rectangle extends Point { private String leftTri; private String len; private String width; public Rectangle() { System.out.println("Rectangle Class"); } public String getLeftTri() { return leftTri; } public void setLeftTri(String leftTri) { this.leftTri = leftTri; } public String getLen() { return len; } public void setLen(String len) { this.len = len; } public String getWidth() { return width; } public void setWidth(String width) { this.width = width; } } class Cube extends Point { public Cube() { System.out.println("Cube Class"); } }

public class RectangleDemo//父类 { protected int width; protected int height; public RectangleDemo() { } public RectangleDemo(int width,int height) { this.width=width; this.height=height; } public void setWidth(int width) { this.width=width; } public void setHeight(int height) { this.height=height; } public int getWidth() { return width; } public int getHeight() { return height; } public int getArea() { return width*height; } } public class Cubic extends RectangleDemo//子类 { protected int length; public Cubic() { super(); } public Cubic(int width,int height,int length) { super(width,height); this.length=length; } public void setLength(int length) { this.length=length; } public int getLength() { return length; } public int getCubic() { //return width*height*length; return super.getArea()*length;//调用父类的方法getArea() } } public class CubicDemo//测试函数 { public static void main(String[] args){ Cubic cub1=new Cubic(); Cubic cub2=new Cubic(2,3,4); System.out.printf("%d,%d,%d \n",cub1.getWidth(),cub1.getHeight(),cub1.getLength()); System.out.printf("%d,%d,%d \n",cub2.getWidth(),cub2.getHeight(),cub2.getLength()); System.out.println(cub2.getCubic()); cub2.width=5;//直接调用父类的声明为protected的域成员 System.out.printf("%d,%d,%d \n",cub2.getWidth(),cub2.getHeight(),cub2.getLength()); System.out.println(cub2.getCubic()); } }

//Point.java public class Point { private int x; private int y; public int getX() { return x; } public void setX(int x) { this.x = x; } public int getY() { return y; } public void setY(int y) { this.y = y; } public Point(int x, int y) { this.x=x; this.y=y; } } //Rectangle.java public class Rectangle extends Point{ private int x; private int y; private int width; private int height; public Rectangle(int x, int y) { super(x, y); // TODO Auto-generated constructor stub } public Rectangle(int x2, int y2, int width, int height) { super(x2, y2); this.x = x2; this.y = y2; this.width = width; this.height = height; } public int getWidth() { return width; } public void setWidth(int width) { this.width = width; } public int getHeight() { return height; } public void setHeight(int height) { this.height = height; } } //Cube.java public class Cube extends Point{ private int x; private int y; private int z; private int length; private int width; private int heigth; public Cube(int x, int y, int z, int length, int width, int heigth) { super(x, y); x = x; y = y; this.z = z; this.length = length; this.width = width; this.heigth = heigth; } public int getLength() { return length; } public void setLength(int length) { this.length = length; } public int getWidth() { return width; } public void setWidth(int width) { this.width = width; } public int getHeigth() { return heigth; } public void setHeigth(int heigth) { this.heigth = heigth; } public int getZ() { return z; } public void setZ(int z) { this.z = z; } } //测试类T.java import java.awt.*; import java.awt.event.*; public class T{ public static void main(String args[]) { Point p = new Point(1,2); Rectangle r = new Rectangle(5,5,200,300); Cube c = new Cube(10,10,10,15,10,25); System.out.print("长方形的位置、长、宽分别为："); System.out.println("("+r.getX()+","+r.getY()+")、"+r.getWidth()+"、"+r.getHeight()); System.out.print("立方体的位置、长、宽、高分别为："); System.out.println("("+c.getX()+","+c.getY()+","+c.getZ()+")、"+c.getLength()+"、"+c.getWidth()+"、"+c.getHeigth()); } } 您的进步是我最大的动力，如果你觉得我回答的合理的话，请给我多加分。谢谢，如果不明白的话，大家相互学习啊！