1 00:00:00,660 --> 00:00:07,010 So now inside the main class I just need to refer to the name of my class that speed. 2 00:00:07,580 --> 00:00:07,850 OK. 3 00:00:07,860 --> 00:00:15,530 As you can see I managed to successfully access this class valuable OK by just using the class itself. 4 00:00:15,750 --> 00:00:17,800 And then I put the dot notation here. 5 00:00:17,970 --> 00:00:21,600 And then I accessed this class variable here. 6 00:00:21,600 --> 00:00:27,000 So now if I want to output the value of my class value to the console I just need to type in here system 7 00:00:27,810 --> 00:00:35,000 that out that insulin and then inside the apprentice's I can just put this statement here. 8 00:00:35,190 --> 00:00:35,620 OK. 9 00:00:35,730 --> 00:00:38,980 And then I need to put in a semicolon at the end of my statement. 10 00:00:39,180 --> 00:00:45,760 And now if I get on my project as you can see this is the value of the speed class variable. 11 00:00:45,800 --> 00:00:46,190 OK. 12 00:00:46,200 --> 00:00:47,470 One hundred and eighty. 13 00:00:47,640 --> 00:00:52,750 OK so as you can see here are the value of this class variable is one hundred and eighty. 14 00:00:52,870 --> 00:00:56,480 OK so now I want to actually create a class method. 15 00:00:56,520 --> 00:01:02,290 So let me try to change this public access modifier to private OK. 16 00:01:02,490 --> 00:01:10,980 And then let me actually delete this static keyword here and now I want to actually create a class method. 17 00:01:11,070 --> 00:01:15,390 So after this public access modify it I just need to type in static. 18 00:01:16,230 --> 00:01:20,430 And as you can see here it's going to actually show us an error here. 19 00:01:20,430 --> 00:01:27,630 So let's actually hover over the error area and see what's the error cannot make a static reference 20 00:01:27,960 --> 00:01:30,180 to the non-static field speed. 21 00:01:30,180 --> 00:01:30,680 OK. 22 00:01:30,780 --> 00:01:36,750 So as you can see here it says that our speed instance variable here is not static. 23 00:01:36,900 --> 00:01:40,770 So we must actually put the static keyword here. 24 00:01:41,070 --> 00:01:44,930 In order to refer to this special class variable here. 25 00:01:44,940 --> 00:01:45,380 OK. 26 00:01:45,390 --> 00:01:49,610 Because you actually changed this method to a class method. 27 00:01:49,650 --> 00:01:56,550 OK we put this static vote after our public access modifier in order to make this method a class method. 28 00:01:56,670 --> 00:01:57,050 OK. 29 00:01:57,060 --> 00:01:59,590 Before that it was only an instance method. 30 00:01:59,620 --> 00:02:03,290 OK but now it is a class method. 31 00:02:03,540 --> 00:02:05,620 So here inside the main class. 32 00:02:05,640 --> 00:02:07,960 So as you can see here it's now showing us an error. 33 00:02:08,100 --> 00:02:14,700 So if I hover over the area it says the field where that speed is not visible because we actually changed 34 00:02:14,910 --> 00:02:18,500 the axis modifier of this class variable to private. 35 00:02:18,510 --> 00:02:24,610 So we have not referred to this class variable from outside of this class. 36 00:02:24,750 --> 00:02:27,080 So I just need to delete this line of code here. 37 00:02:27,420 --> 00:02:33,170 And now I want to actually see the value of that speed class variable by using that term ever. 38 00:02:33,180 --> 00:02:40,070 Ok so I just need to type in here system that out that gentleman and it inside the. 39 00:02:40,290 --> 00:02:43,580 I can just refer to the name of my class Bert. 40 00:02:44,480 --> 00:02:50,940 OK that gets spit and then at the end of my statement I need to put in a semi-colon. 41 00:02:50,940 --> 00:02:57,450 So as you can see here if I run my project as you can see this is the value of that speed class variable. 42 00:02:57,540 --> 00:02:58,350 OK. 43 00:02:58,890 --> 00:03:04,750 So I managed to successfully access the value of this Spaeth class variable. 44 00:03:05,010 --> 00:03:05,640 OK. 45 00:03:05,640 --> 00:03:10,020 So as you can see here I didn't create any object from this class. 46 00:03:10,050 --> 00:03:16,530 I did actually referred to the name of this class and then I did access this my fed by just referring 47 00:03:16,570 --> 00:03:17,520 to the name of this method. 48 00:03:17,550 --> 00:03:18,070 OK. 49 00:03:18,090 --> 00:03:20,670 And that's because of these static keyword here. 50 00:03:20,760 --> 00:03:21,330 OK. 51 00:03:21,330 --> 00:03:28,440 In order to make a valuable or a method a class valuable or a class method we need to put the static 52 00:03:28,440 --> 00:03:30,640 keyword after our access modifier. 53 00:03:30,660 --> 00:03:31,510 OK. 54 00:03:31,830 --> 00:03:39,040 And here again I can actually put this static keyword here static and it inside of the main class. 55 00:03:39,160 --> 00:03:43,060 I can just refer to the name of this class method. 56 00:03:43,110 --> 00:03:50,640 And now I can just refer to the name of my class bird that said speed and I can actually pass a value 57 00:03:50,640 --> 00:03:51,300 to this. 58 00:03:51,300 --> 00:03:53,450 For example number 25. 59 00:03:53,790 --> 00:04:00,360 And here as you can see I actually changed the value of this speed class variable here. 60 00:04:00,440 --> 00:04:03,780 OK the value of this speed class value is 25. 61 00:04:03,900 --> 00:04:11,430 And remember that I told you this earlier in this tutorial with class variables only one copy of that 62 00:04:11,430 --> 00:04:14,420 value exists when the class is loaded. 63 00:04:14,560 --> 00:04:20,880 Changing the value of that variable changes it for all instances of that class. 64 00:04:20,880 --> 00:04:21,380 OK. 65 00:04:21,600 --> 00:04:26,750 So now the value of the speed class value is 25. 66 00:04:26,790 --> 00:04:34,680 And if you create any object from that birth class the value of that Spaeth class valuable is 25 not 67 00:04:34,680 --> 00:04:35,990 one hundred and eighty. 68 00:04:36,090 --> 00:04:36,770 OK. 69 00:04:37,050 --> 00:04:43,080 So as you can see here if you want to access the value of that speed class variable and output that 70 00:04:43,080 --> 00:04:44,120 value to the console. 71 00:04:44,220 --> 00:04:52,950 Let's see what happens system that out that insulin and that inside the prentices I can just refer to 72 00:04:52,950 --> 00:05:01,640 the name of my class bird that gets beat and then at the end of my statement I need to put in a semi-colon. 73 00:05:01,830 --> 00:05:07,400 So now if you're on my project as you can see the value of that class variable and the value of the 74 00:05:07,400 --> 00:05:09,540 speed class value bet is 25. 75 00:05:09,690 --> 00:05:15,390 And now I want to actually create an object from this birth class. 76 00:05:15,390 --> 00:05:17,500 So I just need what I can hear birds. 77 00:05:18,030 --> 00:05:23,590 And the name of my object is my second bird. 78 00:05:24,180 --> 00:05:30,220 And then I put an assignment operator here and I put this key vote here Neo. 79 00:05:30,390 --> 00:05:37,690 And then I refer to the name of my class bird and then I put in a program and I get after my class. 80 00:05:37,770 --> 00:05:43,260 And here I want to actually access the value of this speech class value add and outputs that value to 81 00:05:43,260 --> 00:05:43,770 the concert. 82 00:05:43,770 --> 00:05:44,230 OK. 83 00:05:44,340 --> 00:05:50,190 So I just need to type in here system that out that printed then and then inside the parenthesis I can't 84 00:05:50,190 --> 00:05:51,930 just refer to the name of my object. 85 00:05:51,930 --> 00:06:04,420 My second bird that gets speed we can actually refer to our class benefits by using odd objects. 86 00:06:04,440 --> 00:06:04,840 OK. 87 00:06:04,860 --> 00:06:10,880 So now if I don't on my project as you can see the value of the speed class variable is again 25. 88 00:06:10,890 --> 00:06:11,630 Why. 89 00:06:11,670 --> 00:06:15,510 Because this speed valuable is actually a class variable. 90 00:06:15,540 --> 00:06:16,010 OK. 91 00:06:16,170 --> 00:06:23,160 And if we change the value of this variable that value is going to be changed for all of our instances 92 00:06:23,160 --> 00:06:24,060 from this class. 93 00:06:24,060 --> 00:06:24,720 OK. 94 00:06:24,900 --> 00:06:28,140 And let me actually tell you again with class variables. 95 00:06:28,170 --> 00:06:32,290 Only one copy of that variable exists when the class is loaded. 96 00:06:32,310 --> 00:06:32,980 OK. 97 00:06:33,000 --> 00:06:38,450 Changing the value of that variable changes it for all instances of that class. 98 00:06:38,660 --> 00:06:45,060 OK so now if I actually want to change that value again I just need to type in here my second bird that 99 00:06:45,420 --> 00:06:49,320 said speed for example 45. 100 00:06:49,830 --> 00:06:55,210 And as you can see the value of this class variable is 45. 101 00:06:55,380 --> 00:07:00,250 And if you want to output that value to the console I just need to type in here a system that out that 102 00:07:00,340 --> 00:07:05,850 insulin and and inside the prentices I just need to refer to the name of my object or I can actually 103 00:07:05,850 --> 00:07:13,860 refer to the name of my class because that's value it is a class variable that gets beat and I need 104 00:07:13,860 --> 00:07:16,220 to put in a semicolon at the end of my statement. 105 00:07:16,530 --> 00:07:21,680 And if I run my project again as you can see the value of the speed class value is 45. 106 00:07:21,740 --> 00:07:22,420 OK. 107 00:07:22,530 --> 00:07:29,610 And now if I want to actually create another object from my birth class I just need to type in here 108 00:07:29,640 --> 00:07:37,820 word my first birth and then I put an assignment operator here. 109 00:07:38,010 --> 00:07:44,010 And then I put the new word here and then I refer to the name of my class and I put in a pair of round 110 00:07:44,010 --> 00:07:46,120 brackets after my class name. 111 00:07:46,170 --> 00:07:49,790 So as you can see here my first birth object is now created. 112 00:07:49,950 --> 00:07:55,400 So I even try to access the value of this Spaeth class variable and outputs that value to the console. 113 00:07:55,410 --> 00:08:03,360 So I just need to type in here a system that's out to print to learn and then inside the apprentice's 114 00:08:03,630 --> 00:08:08,880 I can just refer to the name of my object or I can refer to the name of my class. 115 00:08:08,880 --> 00:08:19,470 My first object that get speed and as you can see it's going to output the value number 45 to the console. 116 00:08:19,710 --> 00:08:21,600 So as you can see here this is that video. 117 00:08:21,600 --> 00:08:22,190 OK. 118 00:08:22,410 --> 00:08:27,980 And inside that first class I can even change the Smurfette this instance method. 119 00:08:28,020 --> 00:08:35,730 So know that we call these behaviors instance Smif it's OK if we don't put the static keyboard before 120 00:08:35,740 --> 00:08:36,600 the method itself. 121 00:08:36,660 --> 00:08:37,030 OK. 122 00:08:37,050 --> 00:08:44,270 If we put this static keyboard after this axis modifier static as a citizen if it is going to be a class 123 00:08:44,400 --> 00:08:44,790 it. 124 00:08:44,880 --> 00:08:45,530 OK. 125 00:08:45,810 --> 00:08:53,430 So inside the main class I can't even the first of the name of my class bird does fly. 126 00:08:54,240 --> 00:08:58,950 So I can't even run my project as I can see this value is output to the console. 127 00:08:58,990 --> 00:09:06,740 OK so now I want to actually show you another important point about class methods in Java. 128 00:09:06,750 --> 00:09:10,320 So for example inside the main class I want to create MFA. 129 00:09:10,350 --> 00:09:10,870 OK. 130 00:09:11,070 --> 00:09:16,830 So here I just need to type in so first that what I need to specify the access modifier of my method. 131 00:09:16,920 --> 00:09:20,080 So the access modifier of mine if it is public. 132 00:09:20,570 --> 00:09:21,200 OK. 133 00:09:21,630 --> 00:09:25,070 And I need to specify the return type of my method. 134 00:09:25,140 --> 00:09:32,560 So the return type of my method void and the name of my method is for example my fifth one. 135 00:09:32,850 --> 00:09:39,030 And then I need to put in a pair of round brackets after my method name and then I need to open and 136 00:09:39,030 --> 00:09:44,160 close my Meffert by using these curly braces and inside the Meffert I can put in my statements. 137 00:09:44,160 --> 00:09:52,950 So I just type in here system that out that princeling line and then inside the apprentice's I can just 138 00:09:53,520 --> 00:09:57,770 put it into double quotes and then inside the code I can put in my text.