public class Rectangle{
    private int length,width;
    class Rectangle(){
        this.length=i;
        this.width=j;
        System.out.println("Premeter is"+((i+j)*2));
    }
    class Rectangle(int a,int b){
        this.Rectangle();
        this.length=a;
        this.width=b;
        int area;
        area=a*b;
        System.out.println("area is"+area);
    }
    public static void main(String args[]){
        Rectangle Rec=new Rectangle();
        Rec(5,10);
    }
}
        这个代码有什么错误呀，求指出

嗯，我改出来了，初学java，太菜了，嘿嘿。谢谢你！