Java计算矩形面积

求指点，自己看不出来问题
import java.util.Scanner;
public class Rectangle {
public static void main(String[] args) {
try (Scanner reader = new Scanner(System.in)) {
double width;
double height;
double grith;
double area;
width=reader.nextInt();
height=reader.nextInt();
double showGrith(double a,double b) {
width=a;
length=b;
grith = (width+height)2;
return grith;
}
double showArea(double width,double height) {
area=widthheight;
return area;
}
System.out.println(grith);
System.out.println(area);
}
}

}

 public static void main(String[] args) {

        double width = 0;
        double height = 0;

        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入矩形的长度：");
        width = scanner.nextDouble();
        System.out.println("请输入矩形的宽度：");
        height = scanner.nextDouble();
        System.out.println("矩形的周长是：" + (width + height) * 2);
        System.out.println("矩形的面积是：" + width * height);
    }

怎么会把类的属性写到主函数里面去呢？