OnJava8-Examples/reuse/FinalOverridingIllusion.java at master · xinan-w/OnJava8-Examples · GitHub

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// reuse/FinalOverridingIllusion.java

// We make no guarantees that this code is fit for any purpose.

// Visit http://OnJava8.com for more book information.

// It only looks like you can override

// a private or private final method

class WithFinals {

// Identical to "private" alone:

private final void f() {

System.out.println("WithFinals.f()");

}

// Also automatically "final":

private void g() {

System.out.println("WithFinals.g()");

}

class OverridingPrivate extends WithFinals {

private final void f() {

System.out.println("OverridingPrivate.f()");

}

private void g() {

System.out.println("OverridingPrivate.g()");

}

class OverridingPrivate2 extends OverridingPrivate {

public final void f() {

System.out.println("OverridingPrivate2.f()");

}

public void g() {

System.out.println("OverridingPrivate2.g()");

}

public class FinalOverridingIllusion {

public static void main(String[] args) {

OverridingPrivate2 op2 = new OverridingPrivate2();

op2.f();

op2.g();

// You can upcast:

OverridingPrivate op = op2;

// But you can't call the methods:

//- op.f();

//- op.g();

// Same here:

WithFinals wf = op2;

//- wf.f();

//- wf.g();

}

/* Output:

OverridingPrivate2.f()

OverridingPrivate2.g()

OnJava8-Examples/reuse/FinalOverridingIllusion.java at master · xinan-w/OnJava8-Examples · GitHub

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