public methods in package-private classes

Question

Does it make a difference to mark methods as public in package-private classes?

class SomePackagePrivateClass {     void foo();          // package private method      public void bar();   // public method } 

Is there any practical difference in visibility between foo and bar here?

Answer 1

Example using inheritance:

A.java

package pkg1  class A {   void foo();   public void bar() {}; } 

B.java

package pkg1  public class B extends A{  } 

C.java

package pkg2  public class C {   public void doSomething() {    B b = new B();    b.bar(); //ok    b.foo(); //won't work, since foo() is not visible outside of package 'pkg1'     A a = new A(); //won't work since A is not visible outside of package 'pkg1'    a.bar(); //won't work, since a cannot be created   } } 

Answer 2

If the class is not going to be extended by another, more visible subclass*, the only difference is clarity of intent. Declaring all methods package private makes it more difficult for future readers to determine which of the methods are meant to be called by other classes in the same package.

*_{which would not make much sense as a design solution to me, but technically is possible nevertheless.}