Java Puzzles: classier puzzlers

class Base {
    public String className = "Base";
}

class Derived extends Base {
    private String className = "Derived";
}

public class PrivateMatter {
    public static void main(String[] args) {
        System.out.println(new Derived().className);
    }
}

public class StrungOut {
    public static void main(String[] args) {
        String s = new String("Hello world");
        System.out.println(s);
    }
}

class String {
    private final java.lang.String s;

    public String(java.lang.String s) {
        this.s = s;
    }

    public java.lang.String toString() {
        return s;
    }
}

public class ShadesOfGray {
    public static void main(String[] args){
        System.out.println(X.Y.Z);
    }
}

class X {
    static class Y {
        static String Z = "Black";
    } 

    static C Y = new C();
}

class C {
    String Z = "White";
}

public class FadeToBlack {
    // This method should read and print the value of the field Z in class X.Y
    public static void main(String[] args){
    }
}

class X {
    static class Y {
        static String Z = "Black";
    } 

    static C Y = new C();
}

class C {
    String Z = "White";
}

package click;
public class CodeTalk {
    public void doIt() {
        printMessage();
    }

    void printMessage() {
        System.out.println("Click");
    }
}

package hack;
import click.CodeTalk;

public class TypeIt {
    private static class ClickIt extends CodeTalk {
        void printMessage() {
            System.out.println("Hack");
        }
    }

    public static void main(String[] args) {
        ClickIt clickit = new ClickIt();
        clickit.doIt();
    }
}

import static java.util.Arrays.toString;

class ImportDuty {
    public static void main(String[] args) {
        printArgs(1, 2, 3, 4, 5);
    }

    static void printArgs(Object... args) {
        System.out.println(toString(args));
    }
}

class Jeopardy {
    public static final String PRIZE = "$64,000";
}

public class DoubleJeopardy extends Jeopardy {
    public static final String PRIZE = "2 cents";

    public static void main(String[] args) {
        System.out.println(DoubleJeopardy.PRIZE);
    }
}

package client;

import library.Api;

/**
 * This class must make use of some member or constructor exported by
 * library.Api, such that this class (client.Client) compiles if and only if
 * the commented-out private declaration in the source file for library.Api
 * remains commented out.
 */
public class Client {

}

package library;

/**
 * This class may contain any desired code.  It must contain a commented-out
 * private declaration that causes the client (client.Client) to fail
 * to compile when uncommented. No prohibition is placed on what classes
 * or interfaces Api may extend or implement.
 */
public final class Api {

}

public class Conundrum {
    public static void main(String[] args) {
        Enigma e = new Enigma();
        System.out.println(e.equals(e));
    }
}

final class Enigma {
    // Provide a class body that makes Conundrum print false.
    // Do *not* override equals.
}

import java.util.Random;

public class CoinSide {
    private static Random rnd = new Random();

    public static CoinSide flip() {
        return rnd.nextBoolean() ? 
            Heads.INSTANCE : Tails.INSTANCE;
    }

    public static void main(String[] args) {
        System.out.println(flip());
    }
}

class Heads extends CoinSide {
    private Heads() { }
    public static final Heads INSTANCE = new Heads();

    public String toString() {
        return "heads";
    }
}

class Tails extends CoinSide {
    private Tails() { }
    public static final Tails INSTANCE = new Tails();

    public String toString() {
        return "tails";
    }
}