创建对象内存分析：
package oop.Demon3;

public class Application {
public static void main(String[] args) {

    Pet dog = new Pet();
    dog.name = "旺财";
    dog.age = 3;
    dog.shout();

    System.out.println(dog.name);
    System.out.println(dog.age);
}

}

第二个文件：

package oop.Demon3;

public class Pet {
public String name;
public int age;

//无参构造
public void shout(){
    System.out.println("叫了一声");
}

}