مشكلة في بناء الكلاس و استدعاءها

مشكلتي اليوم في بناء الكلاس و استدعاءها

هي سهلة جدا على الكثير من المتعمقين في الجافا

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package javaapplication4;

/**
 *
 * @author Administrator
 */
public class Demo {
    public static void main(String[] args) {
        Person person = new Person();
        person.setName("Patrice");
        System.out.println(person);

        Person person2 = new Person("Stewrt",23);
        System.out.println(person2);
    }

}

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package javaapplication4;

/**
 *
 * @author Administrator
 */
public class Person {

    // varible 
    private String name;
    private int age;
    // constractor

    public Person() {

        name = "Defailt Name";
        age = 10;
    }

     public Person(String theName, int theAge) {

        this.age = age;
        this.name = name;

    }

    public void setAge(int age) {
        this.age = age;
    }

    public void setName(String name) {

        this.name = name;
    }

    public String getName() {
        return name;
    }

    public int getAge() {

        return age;
    }

    public String toString() {
        StringBuffer sb = new StringBuffer();
        sb.append("\nName: " + this.name);
        sb.append("\nAge: " + this.age );
        return sb.toString();
    }
}