object class

object class是所有類別的superclass

String str1 = "hello";
//直接將hello的記憶體位置給str1，str1的位置=hello的位置。
String str2= new String("hello");
//先分配一個記憶體空間給str2，接著，內容值是存放






public class TestEquals
{
  public static void main(String[] args)
  {
    MyDate  date1 = new MyDate(14, 3, 1976);
    MyDate  date2 = new MyDate(14, 3, 1976);
    if ( date1 == date2 ) {
      System.out.println("date1 is identical to date2");
    } else {
      System.out.println("date1 is not identical to date2");
    }
    if ( date1.equals(date2) ) {
      System.out.println("date1 is equal to date2");
    } else {
      System.out.println("date1 is not equal to date2");
    }
    System.out.println("set date2 = date1;");
    date2 = date1;
    if ( date1 == date2 ) {
      System.out.println("date1 is identical to date2");
    } else {
      System.out.println("date1 is not identical to date2");
    }
  }
}