// concurrent/SharedConstructorArgument.java

// (c)2021 MindView LLC: see Copyright.txt

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

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

import java.util.concurrent.atomic.*;

interface SharedArg {

int get();

}

class Unsafe implements SharedArg {

private int i = 0;

@Override public int get() { return i++; }

}

class Safe implements SharedArg {

private static AtomicInteger counter =

new AtomicInteger();

@Override public int get() {

return counter.getAndIncrement();

}

}

class SharedUser implements HasID {

private final int id;

SharedUser(SharedArg sa) {

id = sa.get();

}

@Override public int getID() { return id; }

}

public class SharedConstructorArgument {

public static void main(String[] args) {

Unsafe unsafe = new Unsafe();

IDChecker.test(() -> new SharedUser(unsafe));

Safe safe = new Safe();

IDChecker.test(() -> new SharedUser(safe));

}

}

/* Output:

16537

0

*/