1 00:00:00,510 --> 00:00:08,100 Our class can have several different constructors each with a different number or type of argument when 2 00:00:08,100 --> 00:00:09,860 you use the new keyboard. 3 00:00:10,020 --> 00:00:18,180 You can specify different arguments in the argument list and the correct constructor for those arguments 4 00:00:18,240 --> 00:00:19,150 is called. 5 00:00:19,350 --> 00:00:25,350 So in the previous tutorials I showed you how you can actually create different constructors and how 6 00:00:25,350 --> 00:00:27,210 you can call those constructors. 7 00:00:27,210 --> 00:00:27,680 OK. 8 00:00:27,810 --> 00:00:34,580 In this example here in this application as you can see here as three tokenizer class has multiple constructors. 9 00:00:34,610 --> 00:00:38,980 OK a constructor with only one argument as you can see here. 10 00:00:39,210 --> 00:00:42,080 And a constructor with two arguments. 11 00:00:42,090 --> 00:00:42,560 OK. 12 00:00:42,600 --> 00:00:49,800 When you create your own classes you can define as many constructors as you'll need to implement the 13 00:00:49,800 --> 00:00:51,450 behavior of the class. 14 00:00:51,450 --> 00:00:58,890 No two constructors in a class can have the same number and type of arguments because this is the only 15 00:00:58,890 --> 00:01:02,860 way constructivists are differentiated from each other. 16 00:01:02,960 --> 00:01:03,570 OK. 17 00:01:03,930 --> 00:01:10,230 As I actually showed you in the previous tutorials that your constructors cannot have the same number 18 00:01:10,290 --> 00:01:11,730 and type of arguments. 19 00:01:11,760 --> 00:01:12,600 OK. 20 00:01:12,900 --> 00:01:18,710 Because that is the only way constructors are differentiated from each other. 21 00:01:18,870 --> 00:01:27,060 If a class defines no constructor is a constructor with no arguments is called by default then an object 22 00:01:27,240 --> 00:01:28,880 of the class is created. 23 00:01:28,950 --> 00:01:36,090 So now that you are familiar with Java programming language you may ask yourself that whether the new 24 00:01:36,210 --> 00:01:43,200 operator here this new operator here this new keyboard has an opposite that destroys an object when 25 00:01:43,200 --> 00:01:44,740 it is no longer needed. 26 00:01:44,940 --> 00:01:49,400 Memory management in Java is dynamic and automatic. 27 00:01:49,680 --> 00:01:57,210 When you create a new object Java automatically allocates the proper amount of memory for that object. 28 00:01:57,210 --> 00:02:02,170 You don't have to allocate any memory for objects explicitly. 29 00:02:02,250 --> 00:02:06,730 The Java virtual machine or JVM does that job for you. 30 00:02:06,870 --> 00:02:10,780 OK so that's why Java is so easy and powerful. 31 00:02:10,790 --> 00:02:14,060 OK because Java memory management is automatic. 32 00:02:14,160 --> 00:02:20,730 You don't need to deallocate the memory an object uses when you you're finished using it. 33 00:02:20,730 --> 00:02:26,820 Under most circumstances when you are finished with an object when you are finished with an object you 34 00:02:26,820 --> 00:02:34,280 have created Jova can determine that the object no longer has any life references to it. 35 00:02:34,320 --> 00:02:39,300 OK in other words the object isn't assigned to any value. 36 00:02:39,300 --> 00:02:49,410 Bell is still in use or stored in as it program runs the JVM periodically looks for unused objects and 37 00:02:49,470 --> 00:02:53,470 reclaims the memory that those objects are using. 38 00:02:53,700 --> 00:02:57,840 This process is called Dynamic garbage collection. 39 00:02:57,840 --> 00:03:04,650 You don't have to explicitly free the memory taken up by an object you just have to make sure that you 40 00:03:04,650 --> 00:03:09,040 are not still holding onto an object you want to get rid of. 41 00:03:09,060 --> 00:03:10,890 OK so this is odd. 42 00:03:11,010 --> 00:03:16,800 This is one of the most powerful feature of the Java programming language. 43 00:03:16,820 --> 00:03:24,760 Ok so I think that's enough for this tutorial and indeed this tutorial will going to create our first 44 00:03:24,850 --> 00:03:26,820 Android application. 45 00:03:27,010 --> 00:03:32,290 So if you have any questions please post the discussion in the course and then I'll do my best to answer 46 00:03:32,290 --> 00:03:33,510 your questions. 47 00:03:33,760 --> 00:03:35,640 And thank you very much for watching. 48 00:03:35,800 --> 00:03:37,700 I'll see you in the next tutorial.