2015-6-13

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经过几天讲解和练习，实现了继承的实例，

在此过程中，感觉主要难度在于子类的继承对象以及强制转换，

例：

import java.awt.Color;
import java.awt.Graphics;
public class Line extends Shape{
public Line(int x1, int y1, int x2, int y2, Color color) {
super(x1, y1, x2, y2, color);
// TODO Auto-generated constructor stub}
public void draw(Graphics g) {
g.drawLine(x1, y1, x2, y2);
}

}

if ("10".equals(draw.str)) {
// draw.g.drawLine(x1, y1, x2, y2);
// 创建一个直线对象
shape = new Line(x1,y1,x2,y2,draw.color);
x1 = x2;
y1 = y2;

再如：

} else if ("2".equals(draw.str)) {

draw.g.setColor(Color.white);
BasicStroke basicstroke = new BasicStroke(10);
Shape shape = new Coph(x1,y1,x2,y2,draw.color.white);
Graphics2D graphics2d = (Graphics2D) draw.g;
graphics2d.setStroke(basicstroke);
draw.g.drawLine(x1, y1, x2, y2);
list.add(shape);
x1 = x2;
y1 = y2;

总之，强制转化得新建一对象，毕竟这是子类的属性。

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