// Example 113 from page 87

//

import java.io.IOException;

class Example113 {

public static void main(String[] args) throws IOException {

final MutableInteger mi = new MutableInteger();

Thread t = new Thread(new Runnable() {

public void run() {

while (mi.get() == 0) // Loop while zero

{ }

System.out.println("I completed, mi = " + mi.get());

}

});

t.start();

System.out.println("Press Enter to set mi to 42 and stop the loop:");

System.in.read(); // Wait for enter key

mi.set(42);

System.out.println("mi set to 42, waiting for thread ...");

try { t.join(); } catch (InterruptedException exn) { }

System.out.println("Thread t completed, and so does main");

}

}

// From Goetz et al p. 36. WARNING: Useless without "volatile" or

// "synchronized" to ensure visibility of writes across threads.

class MutableInteger {

private /* volatile */ int value = 0;

public void set(int value) { this.value = value; }

public int get() { return value; }

}