Confusing calling method in Java

Question

class Parent
{
    private void method1()
    {
        System.out.println("Parent's method1()");
    }
    public void method2()
    {
        System.out.println("Parent's method2()");
        method1();
    }
}

class Child extends Parent
{
    public void method1()
    {
        System.out.println("Child's method1()");        
    }
}
class test {
    public static void main(String args[])
    {
        Parent p = new Child();
        p.method2();
    }
}

I'm confuse why does in Parent::method2() when invoking method1() it will cal Parents method1() and not Childs method1 ? I see that this happens only when method1() is private? Can someone explain me why ?
Thanks you.

Mark Elliot · Accepted Answer · 2011-03-14 00:13:21Z

5

This happens based on scoping rules; in Parent the best match for method1 is the class-local private version.

If you were to define method1 as public or protected in Parent and override the method in Child, then calling method2 would invoke Child's method1 instead.

answered Mar 14, 2011 at 0:13

Mark Elliot

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4 Comments

kevpie Over a year ago

for his example, may as well add friendly to the list.

Adrian Over a year ago

i guess he ment friend :) Thanks for explination Mark Elliot

kevpie Over a year ago

Friendly refers to the absence of a public/protected/private designator. Friendly methods are accessible by any class in the same package. Friends, that is what I meant. :)

samarjit samanta Over a year ago

friend concept is in c++ not in java. In java no-modifier or default modifier. These default modifiers are confusing to detect by reflection and hence i dont like them too much, anyway its out of context here.

AdamH · Accepted Answer · 2011-03-14 00:11:58Z

5

private methods can't be overriden, hence the method1 you specify on Child isn't linked. javac assumes you must mean the method1 on the parent. Changing it to protected will work.

answered Mar 14, 2011 at 0:11

AdamH

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1 Comment

Paolo Over a year ago

JLS reference: 8.4.8.1 Overriding (by Instance Methods)

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