java，大神们帮帮忙12题

java，大神们帮帮忙12题

public class Demo {

public static void main(String[] args) {
SanJiaoXing sjx = new SanJiaoXing();
sjx.areaCel(10, 10);
JuXing jx = new JuXing();
jx.areaCel(10, 2);
}

}
abstract class Father{
public abstract double areaCel(int length,int wide);
}

class SanJiaoXing extends Father{
@Override
public double areaCel(int length,int wide) {
double area = length*wide/2;
System.out.println("三角形面积为:"+area);
return area;
}
}
class JuXing extends Father{
@Override
public double areaCel(int length, int wide) {
double area = length*wide;
System.out.println("矩形面积为:"+area);
return area;
}
}
我只写了两个，其他是一样的，希望能帮到你！