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public final class MutableClass { // Copy Constructor
  private final Date date;

  public MutableClass(MutableClass mc)  {
    this.date = new Date(mc.date.getTime());
  }

  public MutableClass(Date d) {
    this.date = new Date(d.getTime());  // Copy-in
  }

  public Date getDate() {
    return (Date) date.clone(); // Copy and return
  }
}

class MutableClass {
  private final Date date;

  private MutableClass(Date d) { // Noninstantiable and nonsubclassable
    this.date = new Date(d.getTime());  // Copy-in
  }

  public Date getDate() {
    return (Date) date.clone(); // Copy and return
  }

  public static MutableClass getInstance(MutableClass mc)  {
    return new MutableClass(mc.getDate());
  }
}

public final class MutableClass implements Cloneable {
  private Date date;

  public MutableClass(Date d) {
    this.date = new Date(d.getTime());
  }

  public Date getDate() {
    return (Date) date.clone();
  }

  public void setDate(Date d) {
    this.date = (Date) d.clone();
  }

  public Object clone() throws CloneNotSupportedException {
    final MutableClass cloned = (MutableClass) super.clone();
    cloned.date = (Date) date.clone();  // manually copy mutable Date object
    return cloned;
  }
}

public final class MutableClass implements Cloneable {
  private final Date date; // final field

  public MutableClass(Date d) {
    this.date = new Date(d.getTime());  // copy-in
  }

  public Date getDate() {
    return (Date) date.clone(); // copy and return
  }

  public Object clone() throws CloneNotSupportedException {
    Date d = (Date) date.clone();
    MutableClass cloned = new MutableClass(d);
    return cloned;
  }
}