Understanding of inheritance in Java

Please don't be angry if my question is stupid )

I have a piece of code:

public class LinkageTest { 

public static class Parent { 

    public void test() { 
        System.out.println("parent::test"); 
    } 
} 

public static class Child extends Parent { 

    public void test() { 
        System.out.println("child::test"); 
    } 
} 

public static class Tester { 

    public void test(Parent obj) { 
        System.out.println("Testing parent..."); 
        obj.test(); 
    } 

    public void test(Child obj) { 
        System.out.println("Testing child..."); 
        obj.test(); 
    } 
} 

public static void main(String[] args) { 
    Parent obj = new Child(); 
    Tester t = new Tester(); 
    t.test(obj); 
} 

}

When I'm running it, the next string is printed:

Testing parent... child::test

I can't understand why test method with Parent is called if we have instance of Child? Can some one help me with it?