1 00:00:00,560 --> 00:00:04,830 This type of constructor is called the default constructor OK. 2 00:00:05,360 --> 00:00:12,080 In this example we are creating the no argument constructor in the Tiger class. 3 00:00:12,170 --> 00:00:16,250 It will be invoked at the time of object creation. 4 00:00:16,500 --> 00:00:24,660 OK so as you can see here inside the main class we are creating an object for this type of class. 5 00:00:24,680 --> 00:00:30,170 So now me actually comment out these lines of code here because I want to create another and other object 6 00:00:30,170 --> 00:00:31,850 from your class. 7 00:00:31,880 --> 00:00:41,860 So first I need to refer to the name of my class and the name of my object is my second tiger. 8 00:00:42,770 --> 00:00:50,120 And then I put an assignment operator here and then I put this key word here new and then I referred 9 00:00:50,120 --> 00:00:57,130 to the name of my class name again Tiger and then I put a pair of down brackets after my classily. 10 00:00:57,270 --> 00:01:02,680 OK so now as you can see I created an object from this tiger class. 11 00:01:02,720 --> 00:01:03,260 OK. 12 00:01:03,470 --> 00:01:11,390 So now the inside of this tiger class I want to actually output some values to the console when ever 13 00:01:11,600 --> 00:01:17,240 an object from the tiger class is created inside of this tiger constructor I just need to type in system 14 00:01:17,660 --> 00:01:24,740 that out that print land and then inside the apprentice's I just need to put in two double quotes and 15 00:01:24,740 --> 00:01:27,930 then inside it all coats I just need to typing this. 16 00:01:30,260 --> 00:01:30,920 Default 17 00:01:33,680 --> 00:01:36,290 constructor OK. 18 00:01:37,010 --> 00:01:44,000 So as you can see here I created a constructor inside of my tiger class and inside of this constructor 19 00:01:44,330 --> 00:01:47,720 I decided to Outwood some values to the console. 20 00:01:47,960 --> 00:01:53,810 So inside the main class as you can see we created an object from this tiger class and the name of this 21 00:01:53,900 --> 00:01:56,060 object is my second tiger. 22 00:01:56,060 --> 00:01:56,800 OK. 23 00:01:56,990 --> 00:02:00,070 So now if I it on my project let's see what happens. 24 00:02:00,230 --> 00:02:04,020 So as you can see here this is the value that is outputted to the console. 25 00:02:04,220 --> 00:02:06,770 And this is our default constructor. 26 00:02:06,770 --> 00:02:07,450 OK. 27 00:02:07,730 --> 00:02:14,240 So inside of this main class and inside of this main method we didn't try to actually output anything 28 00:02:14,240 --> 00:02:22,100 to the console and we only actually created an object from this tile class in line 14 inside of the 29 00:02:22,100 --> 00:02:22,680 main method. 30 00:02:22,700 --> 00:02:23,200 OK. 31 00:02:23,400 --> 00:02:31,190 But inside of the target class we created our default constructor with no arguments and inside of this 32 00:02:31,190 --> 00:02:34,450 constructor I decided to output some values to the console. 33 00:02:34,450 --> 00:02:35,960 OK so this is that value. 34 00:02:36,050 --> 00:02:36,760 OK. 35 00:02:37,220 --> 00:02:41,990 And remember that we can actually create unlimited constructors in our classes. 36 00:02:42,070 --> 00:02:42,600 OK. 37 00:02:42,710 --> 00:02:50,120 So for example this is called the default constructor and I can actually create a padded motorized constructor 38 00:02:50,130 --> 00:02:56,240 OK constructor with argument list is known as padding meteoroids the constructor. 39 00:02:56,240 --> 00:03:02,450 So anality actually comments out of this constructor here and now I want to actually create a parametrized 40 00:03:02,480 --> 00:03:03,170 constructor. 41 00:03:03,220 --> 00:03:14,370 OK so here I just need to type in public OK the access modifier of my constructor is public and the 42 00:03:14,370 --> 00:03:20,760 name of my constructor must be the same as the name of the class Tiger and I need to put on a pair of 43 00:03:20,760 --> 00:03:27,060 round brackets after my constructor name and that I need to open and close my constructor by using these 44 00:03:27,060 --> 00:03:28,160 curly braces. 45 00:03:28,200 --> 00:03:34,110 So as you can see here I want to actually specify that this constructor is going to accept some values. 46 00:03:34,130 --> 00:03:37,300 OK we can actually pass values to the constructor. 47 00:03:37,440 --> 00:03:43,690 So inside of this prentices I can just typing int for example Nahm one. 48 00:03:43,800 --> 00:03:49,000 And then I can actually create another argument ain't none too ok. 49 00:03:49,320 --> 00:03:56,100 I can actually create a variable for example int result and then I can put in an assignment operator 50 00:03:56,100 --> 00:04:01,560 here refers to the name of my non-valid argument plus numb to argument. 51 00:04:01,560 --> 00:04:02,410 OK. 52 00:04:02,730 --> 00:04:07,280 And then I can output the value of the result variable to the console. 53 00:04:07,290 --> 00:04:13,520 So I just need to type in her system thought out that princeling and an inside the practices. 54 00:04:13,530 --> 00:04:18,960 I can't just refer to the name of the results variable and then I need to put in a semi-colon at the 55 00:04:18,960 --> 00:04:20,510 end of my statement. 56 00:04:20,520 --> 00:04:25,910 So now inside of the main class as you can see it's now showing us an error. 57 00:04:25,980 --> 00:04:31,540 OK so let's actually hover our mouse pointer over the error area and see what's the error. 58 00:04:31,590 --> 00:04:36,090 So as you can see here it says de-construct here Tiger is undefined. 59 00:04:36,170 --> 00:04:36,830 OK. 60 00:04:36,960 --> 00:04:43,770 So as you can see here we created a constructor inside of the tiger class that actually accepts arguments. 61 00:04:43,770 --> 00:04:44,410 OK. 62 00:04:44,670 --> 00:04:48,670 So the default constructor is not going to be called anymore. 63 00:04:49,080 --> 00:04:53,000 So we need to actually call this constructor from now on. 64 00:04:53,070 --> 00:04:53,640 OK. 65 00:04:53,850 --> 00:05:01,830 So inside of the main class if I actually delete this tiger class name here and if I just refer to the 66 00:05:01,830 --> 00:05:08,400 name of my pager class and if I actually use the autocomplete feature of the eclipse by pressing under 67 00:05:08,400 --> 00:05:15,180 control key plus the space key on my keyboard as you can see it's now recommending us to choose this 68 00:05:15,180 --> 00:05:21,390 option here Tiger and in say the prentices is not one comma in into number two. 69 00:05:21,480 --> 00:05:26,490 So if I choose this option as you can see I can actually pass some values here. 70 00:05:26,520 --> 00:05:29,110 The first value that you want to pass is number two. 71 00:05:29,190 --> 00:05:32,310 And the second value that you want to pass is number four. 72 00:05:32,640 --> 00:05:36,640 And I need to put in a semi-colon at the end of my statement. 73 00:05:36,660 --> 00:05:40,360 So now if I get on my project let's see what happens. 74 00:05:40,440 --> 00:05:43,270 As you can see this value is now outputted to the console. 75 00:05:43,380 --> 00:05:49,910 So as you can see here in line 14 I created an object from the tiger class. 76 00:05:50,120 --> 00:05:50,730 OK. 77 00:05:50,730 --> 00:05:52,410 So then my project runs. 78 00:05:52,620 --> 00:05:56,350 It's going to first actually run the codes inside of this main if. 79 00:05:56,370 --> 00:05:56,810 OK. 80 00:05:56,850 --> 00:06:03,630 And inside of this main effect I created an object from this tiger class in line 14. 81 00:06:03,630 --> 00:06:04,110 OK. 82 00:06:04,110 --> 00:06:09,900 And as you know a constructor is a block of code which is going to be run whenever you actually create 83 00:06:09,960 --> 00:06:11,070 an object. 84 00:06:11,070 --> 00:06:11,630 OK. 85 00:06:11,640 --> 00:06:17,720 So then you actually create an object from the target class it's going to actually add on our constructor. 86 00:06:17,730 --> 00:06:18,290 OK. 87 00:06:18,420 --> 00:06:19,620 Inside the Target Class. 88 00:06:19,620 --> 00:06:23,520 So as you can see here this is our constructor for our tiger class. 89 00:06:23,520 --> 00:06:24,240 OK. 90 00:06:24,570 --> 00:06:28,210 And then it's going I cheated on the codes inside of the constructor. 91 00:06:28,410 --> 00:06:36,300 So as you can see here I created a value here called result and then I decided to actually assign the 92 00:06:36,300 --> 00:06:40,710 result of this operation here to this variable and an inline 14. 93 00:06:40,740 --> 00:06:43,540 I decided to Outwood that value to the console. 94 00:06:43,560 --> 00:06:46,400 So this is that value OK number 6. 95 00:06:46,410 --> 00:06:50,190 So number two plus number four is number six. 96 00:06:50,190 --> 00:06:50,970 OK. 97 00:06:51,000 --> 00:06:57,250 So now if I actually comment out this constructor here as you can see let's see what happens inside 98 00:06:57,270 --> 00:06:57,990 the main class. 99 00:06:57,990 --> 00:06:59,610 It's now showing us an error. 100 00:06:59,610 --> 00:07:04,700 So now let's actually hover our mouse pointer over error area and see what's the error. 101 00:07:04,710 --> 00:07:05,260 OK. 102 00:07:05,310 --> 00:07:09,280 As you can see here the constructor's Tiger Prentice's it. 103 00:07:09,320 --> 00:07:11,100 It is undefined. 104 00:07:11,310 --> 00:07:11,910 OK. 105 00:07:12,030 --> 00:07:14,410 What's the problem inside the tiger class. 106 00:07:14,430 --> 00:07:20,840 We don't have any constructor which specifies that it's going to accept two arguments of type integer. 107 00:07:20,880 --> 00:07:21,330 OK. 108 00:07:21,360 --> 00:07:24,560 As you can see here we commented out this constructor here. 109 00:07:24,690 --> 00:07:27,230 So it is not going to be executed anymore. 110 00:07:27,510 --> 00:07:32,220 So we need to actually use the default constructor which has no arguments. 111 00:07:32,220 --> 00:07:34,950 As you can see here now the error is gone. 112 00:07:35,070 --> 00:07:38,120 And if I had on my project again nothing is going to happen here. 113 00:07:38,130 --> 00:07:38,520 OK. 114 00:07:38,520 --> 00:07:41,910 As you can see inside the console Nothing is here. 115 00:07:42,150 --> 00:07:42,450 OK. 116 00:07:42,450 --> 00:07:42,990 Why. 117 00:07:42,990 --> 00:07:46,920 Because you are actually creating an object from the target class as you can see here. 118 00:07:46,980 --> 00:07:50,360 We didn't create any constructor inside of the target class. 119 00:07:50,370 --> 00:07:53,380 So it's going to actually execute the default constructor OK. 120 00:07:53,400 --> 00:07:58,250 And now I want to actually show you and other important point about constructors. 121 00:07:58,260 --> 00:08:03,630 So inside the tigers of a fight as you can see here let's say that let's say that I don't want to actually 122 00:08:03,660 --> 00:08:06,360 assign any values to this instance value but ok. 123 00:08:06,800 --> 00:08:12,600 16 inside the target class I just declare it an instance variable called speed. 124 00:08:12,650 --> 00:08:16,290 I'm not assigning any values to this instance value but OK. 125 00:08:16,490 --> 00:08:19,420 So after creating this instance variable. 126 00:08:19,610 --> 00:08:23,590 Now I want to create another constructor for Tiger class. 127 00:08:23,600 --> 00:08:24,040 OK. 128 00:08:24,140 --> 00:08:28,140 So again the access modifier of this constructor is public. 129 00:08:29,390 --> 00:08:33,850 And the name of the constructor must be the same as the name of the class tiger. 130 00:08:34,000 --> 00:08:34,670 OK. 131 00:08:35,060 --> 00:08:41,300 And I need to put in a pair of and brackets after my constructor name and then I need to open and close 132 00:08:41,300 --> 00:08:43,910 my constructor by using these curly braces. 133 00:08:43,970 --> 00:08:52,610 So now I can actually refer to the name of my spit instance variable and then I can assign a value to 134 00:08:52,610 --> 00:08:54,440 this instance variable. 135 00:08:54,440 --> 00:09:00,710 Ok so now if you want to output that value to the concert I just need to type in system that out that 136 00:09:00,860 --> 00:09:01,730 insulin. 137 00:09:02,000 --> 00:09:07,910 And then inside the prentices I can just refer to the name of my speed instance variable and then I 138 00:09:07,910 --> 00:09:11,200 need to put in a semi-colon at the end of my statement. 139 00:09:11,210 --> 00:09:17,760 So now inside the main class as you can see here I created an object from the tiger class. 140 00:09:17,780 --> 00:09:18,880 OK. 141 00:09:19,250 --> 00:09:22,750 So now if I need on my project let's see what happens. 142 00:09:22,850 --> 00:09:26,630 As you can see this value is now outputted to the console. 143 00:09:26,630 --> 00:09:32,800 This value is the value of this speed instance variable that we created inside the tiger class. 144 00:09:32,810 --> 00:09:33,350 OK. 145 00:09:33,470 --> 00:09:42,320 But we created another constructor here inside the tiger class I assigned a value to this speed instance 146 00:09:42,320 --> 00:09:43,090 variable. 147 00:09:43,100 --> 00:09:48,360 So as you can see here in line 16 I just declared this instance valuable. 148 00:09:48,380 --> 00:09:54,930 But inside of this constructor I decided to actually assign a value to this spit instance variable in 149 00:09:54,940 --> 00:09:55,670 line 19. 150 00:09:55,670 --> 00:09:56,220 OK. 151 00:09:56,360 --> 00:09:57,140 As you can see here.