如何定义类

[奥斯特洛夫司机]

已知类point表示平面上的“点”。请以此类为父类定义一个名为“Line”的子类，他表示一条有两个端点的直线。只主要成员包括：

数据成员：两个端点的坐标（x ，y）直线的宽度w。

方法成员：move（）移动直线，参数：两个端点的坐标：print（）现实数据成员。

[Dan1980]

3楼的代码能运行？自身包含自身，很明显的死循环。

这个题有两种设计思路（本人推荐第二种）：

1. Line继承自Point：

//Point.java
public class Point {
  int x, y;
  public Point(int x, int y) {
    this.x = x;
    this.y = y;
  }
}

//Line.java
public class Line extends Point {
  int x1, y1, w;
  public Line(int startX, int startY, int endX, int endY, int width) {
    super(startX, startY);
    x1 = endX;
    y1 = endY;
    w = width;
  }
  public void move(int newStartX, int newStartY, int newEndX, int newEndY) {
    x = newStartX;
    y = newStartY;
    x1 = newEndX;
    y1 = newEndY;
  }
  public void print() {
    System.out.println("Line: x=" + x + "; y=" + y + "; x1="+ x1 +"; y1=" + y1 + "; w=" + w);
  }
}

2. Line组合Point：

// Point类定义同上

// Line.java
public class Line {
  Point start, end;
  int w;
  public Line(int startX, int startY, int endX, int endY, int width) {
    start = new Point(startX, startY);
    end = new Point(endX, endY);
    w = width;
  }
  public void move(int newStartX, int newStartY, int newEndX, int newEndY) {
    start = new Point(newStartX, newStartY);
    end = new Point(newEndX, newEndY);
  }
  public void print() {
    System.out.println("Line: start from (" + start.x+ "," + start.y + "), end at (" + end.x+ "," + end.y + "), width: " + w);
  }
}

[Dan1980]

3楼的代码能运行？自身包含自身，很明显的死循环。

这个题有两种设计思路（本人推荐第二种）：

1. Line继承自Point：

//Point.java
public class Point {
  int x, y;
  public Point(int x, int y) {
    this.x = x;
    this.y = y;
  }
}

//Line.java
public class Line extends Point {
  int x1, y1, w;
  public Line(int startX, int startY, int endX, int endY, int width) {
    super(startX, startY);
    x1 = endX;
    y1 = endY;
    w = width;
  }
  public void move(int newStartX, int newStartY, int newEndX, int newEndY) {
    x = newStartX;
    y = newStartY;
    x1 = newEndX;
    y1 = newEndY;
  }
  public void print() {
    System.out.println("Line: x=" + x + "; y=" + y + "; x1="+ x1 +"; y1=" + y1 + "; w=" + w);
  }
}

2. Line组合Point：

// Point类定义同上

// Line.java
public class Line {
  Point start, end;
  int w;
  public Line(int startX, int startY, int endX, int endY, int width) {
    start = new Point(startX, startY);
    end = new Point(endX, endY);
    w = width;
  }
  public void move(int newStartX, int newStartY, int newEndX, int newEndY) {
    start = new Point(newStartX, newStartY);
    end = new Point(newEndX, newEndY);
  }
  public void print() {
    System.out.println("Line: start from (" + start.x+ "," + start.y + "), end at (" + end.x+ "," + end.y + "), width: " + w);
  }
}

[wuxo84]

import java.Math.*; 
public class Line extends Point
{
    Point point1; 
    Point point2;
    int   w; 

    public void move( Point point1, Point point2 )
    {
        w = Math.sqrt( ( point1.x - point2.x ) ^2 + ( point1.y - point2.y ) ^2) 
    } 

    public void printPara()
    {
        System.out.println( "Point 1: (" + point1.x + ", " + point1.y + ")");
        System.out.println( "Point 2: (" + point2.x + ", " + point2.y + ")");
        System.out.println( "width: " + w );
    }
}

[wuxo84]

这样写完全是根据lz所描述的那样啊

[wannadream]

首先不明白你说的move()移动直线要的是什么结果，如果是按照三楼计算2点间直线长度，代码如下看看是否可以：

public class Point {

	private int x;

	private int y;

	public Point() {

	}

	public Point(int x, int y) {
		this.x = x;
		this.y = 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 class Line extends Point {

	private Point p1;

	private Point p2;

	private int w;

	public Line(Point p1, Point p2) {
		this.p1 = p1;
		this.p2 = p2;
	}

	public void move() {
		int length = Math.abs(this.p1.getX() - this.p2.getX());
		int height = Math.abs(this.p1.getY() - this.p2.getY());
		w = (int) Math.sqrt((length * length + height * height));
	}

	public void print() {
		System.out.println("Point 1 is : x=" + this.p1.getX() + ",y="
				+ this.p1.getY());
		System.out.println("Point 2 is : x=" + this.p2.getX() + ",y="
				+ this.p2.getY());
		System.out.println("The line width is " + w);
	}

	public static void main(String[] args) {
		Point p1 = new Point(0, 0);
		Point p2 = new Point(3, 4);
		Line l = new Line(p1, p2);
		l.move();
		l.print();
	}
}

[枫叶rain]

这个我以前写过代码
不过现在没时间给你写或者找
可能的话明天给你

[KK3K2005]

定义 点 为 直线 的父类 明显是不恰当的
只能说直线拥有2个点

[redwu99]

import java.Math.*;

public class Line extends Point{
Point point1;
Point point2;
int w;

public void move(){
w=Math.sqrt((point1.x-point2.x)^2+(point1.y-point2.y)^2)

}




}