Find Kirk

FindKirk.java

import java.io.PrintStream;

// Makes it find Kirk every time.
// Works for me every time... but might be system dependent.
public class FindKirk {
  public static void main(String[] args) throws InterruptedException {
    // warmup, avoiding that initialization taking an identity hash code gets in our way
    JavaChampionTest.main();

    // hash code 2134400190 is an early twin. 1802421938 comes 2 before the first occurrence,
    // so run up to that one; then Jack will take the one in between, and the first Kirk gets the
    // first of the twin
    while (new Object().hashCode() != 1802421938);

    // override System.out to do something between the creating of the first and the second Kirk
    // (without changing the original code)
    System.setOut(new PrintStream(System.out) {
      boolean done;
      @Override public void println(String x) {
        // 760371604 comes just before the second occurrence of the twin
        while (!done && new Object().hashCode() != 760371604);
        done = true;
        super.println(x);
      }
    });
    JavaChampionTest.main();
  }
}

JavaChampionTest.java

import java.util.*;

// From http://www.javaspecialists.eu/archive/Issue222.html 
public class JavaChampionTest {
  public static void main(String... args) {
    Map<JavaChampion, String> urls = new HashMap<>();
    urls.put(new JavaChampion("Jack"), "fasterj.com");
    urls.put(new JavaChampion("Kirk"), "kodewerk.com");
    urls.put(new JavaChampion("Heinz"), "javaspecialists.eu");
 
    urls.forEach((p, u) -> System.out.println(u)); // Java 8
 
    System.out.println("URL for Kirk: " +
        urls.get(new JavaChampion("Kirk")));
  }
}
 
final class JavaChampion {
  private final String name;
 
  public JavaChampion(String name) {
    this.name = name;
  }
 
  public boolean equals(Object o) { // simplified equals()
    if (!(o instanceof JavaChampion)) return false;
    return name.equals(((JavaChampion) o).name);
  }
}