Java error i have done everything correct and i m unable to identify mistake. : This is a java code, i have created 4 classes 3 constructor and i am getting error of method area in class Rect cannot be applied to given types; similar error for rest of 2 class aswell. in this program basically i ahve created 4 classes 1 for calculating area of rect 1 for 1 for calculating area of Tri and 1 for calculating area of Square and last one is to acess main function. i have created 3 constructor for all the 3 classes rect tri and square and i am unable to spot the mistake in this program so please help me out with this.   
 
    class Rect    //1st class rect
    {
    double l,b;   //variables
    Rect(double l, double b)     //constructor for rect 
    {
    this.l=l;
    this.b=b;
    }
    double area(double l,double b) //method to cal Rect area
    {
    return l*b;
    }
    }
    class Square   //square class
    {
    double s;
    Square(Double s)   //constructor for class
    {
    this.s=s;
    }
    double area(double s) //method to cal area for square
    {
    return s*s;
    }
    }
    class Tri   // class for triangle 
    {
    double l,b,h;   //variables
    Tri(double l,double b,double h)   // constructor for tri
    {
    this.l=l;
    this.h=h;
    this.b=b;
    }
    double area(double l,double b,double h) //method to cal area for tri
    {
    return 0.5*l*b*h;
    }
    }
    class Area3
    {
    public static void main(String args[])
    {
    Rect r=new Rect(10, 10);  //constructor initialization for Rect
    Square s=new Square(15.0);//constructor initialization for Square
    Tri t=new Tri(10.0,20.0,30.0);//constructor initialization for Tri
    System.out.print(" "+r.area()+""+s.area+""+t.area); //print areas
    }
    }