1 00:00:00,300 --> 00:00:09,840 So I cannot actually create another statement here or system that out that print slant as you can see 2 00:00:09,840 --> 00:00:16,550 here inside Apprentice's just put into double quotes and typing here Heidi for example. 3 00:00:16,560 --> 00:00:17,130 OK. 4 00:00:17,340 --> 00:00:20,220 And then I need to put in a semicolon at the end. 5 00:00:20,220 --> 00:00:26,730 And again if I run my program you can see that that is going to show me the high wire in the console 6 00:00:26,730 --> 00:00:27,290 area. 7 00:00:27,360 --> 00:00:27,990 OK. 8 00:00:28,410 --> 00:00:36,030 But if I comment out this line of code here with multi-line comments as you can see here and now if 9 00:00:36,030 --> 00:00:39,210 I run my project it's going to show us nothing. 10 00:00:39,240 --> 00:00:39,700 OK. 11 00:00:39,730 --> 00:00:48,090 Why why it's not showing us anything because I have commented out this statement here and this is statement 12 00:00:48,090 --> 00:00:48,530 here. 13 00:00:48,610 --> 00:00:49,330 OK. 14 00:00:49,710 --> 00:00:53,500 I have commented out this statement here with a single line comment. 15 00:00:53,520 --> 00:00:59,970 As you can see here and I have commented out this statement here with a multi-line comment. 16 00:01:00,060 --> 00:01:00,780 OK. 17 00:01:01,230 --> 00:01:09,900 So for example if I erase these delimiters here as you can see here and if I run my projects now it's 18 00:01:09,900 --> 00:01:12,120 going to show me the high text here. 19 00:01:12,240 --> 00:01:12,830 OK. 20 00:01:12,990 --> 00:01:20,570 Or if I delete these two slashes here and if I run my project again it's going to show me the hello 21 00:01:20,580 --> 00:01:22,330 text and the text. 22 00:01:22,590 --> 00:01:23,320 OK. 23 00:01:23,490 --> 00:01:25,740 So that's it for comments. 24 00:01:25,790 --> 00:01:28,710 And next I'm going to talk about variables. 25 00:01:28,800 --> 00:01:32,930 Variables are just placeholders for data in our program. 26 00:01:32,970 --> 00:01:33,450 OK. 27 00:01:33,600 --> 00:01:41,810 For example if I to create a variable in my program or first I need to specify the data type of my variable. 28 00:01:41,850 --> 00:01:44,400 For example the data type would be integer. 29 00:01:44,400 --> 00:01:45,050 OK. 30 00:01:45,630 --> 00:01:47,760 As you can see the data type of my variable. 31 00:01:47,760 --> 00:01:49,040 Is it integer. 32 00:01:49,060 --> 00:01:54,030 OK my variable is going to hold an integer number or a whole number. 33 00:01:54,030 --> 00:01:54,720 OK. 34 00:01:55,110 --> 00:01:57,900 And then I need to specify the name of my variable. 35 00:01:57,900 --> 00:01:59,420 For example numbers. 36 00:01:59,600 --> 00:02:00,240 OK. 37 00:02:00,450 --> 00:02:03,360 And that's enough for actually creating a variable. 38 00:02:03,360 --> 00:02:06,140 And at the end I just need to put in a semi-colon. 39 00:02:06,570 --> 00:02:09,420 And as you can see here my variable is now created. 40 00:02:09,570 --> 00:02:10,130 OK. 41 00:02:10,290 --> 00:02:14,560 And optionally I can assign a value to my variable here. 42 00:02:14,570 --> 00:02:16,410 For example number 20. 43 00:02:16,410 --> 00:02:17,020 OK. 44 00:02:17,250 --> 00:02:24,600 So as you can see here I assigned the value 20 as you can see here on the right hand side of the OPERATOR 45 00:02:24,870 --> 00:02:28,300 OK to the left hand side of the operator. 46 00:02:28,380 --> 00:02:31,980 OK so this is not an equal operator. 47 00:02:32,010 --> 00:02:39,630 This is just an assignment operator so you must actually consider that this is an assignment operator 48 00:02:39,630 --> 00:02:47,850 not an equal operator because we are assigning this value on the right hand side of the operator to 49 00:02:47,850 --> 00:02:53,410 the value on the left hand side of the OPERATOR OK so this is very important. 50 00:02:53,820 --> 00:02:57,690 Later I'll explain more about this assignment operator. 51 00:02:57,930 --> 00:03:06,540 But for now just know that this is an assignment operator assigning a value to our variable is called 52 00:03:06,810 --> 00:03:09,010 initialization of that value. 53 00:03:09,300 --> 00:03:14,220 So as you can see here we assigned a value to our variable. 54 00:03:14,220 --> 00:03:17,120 So we just initialize our variable. 55 00:03:17,400 --> 00:03:26,490 So for example if we want to declare another variable ok for example and another number into another 56 00:03:26,790 --> 00:03:33,590 number here I just declare my variable not initializing it. 57 00:03:33,780 --> 00:03:40,940 So as you can see here I didn't assign a value to my order number variable here. 58 00:03:40,950 --> 00:03:44,040 I just declared my variable OK. 59 00:03:44,490 --> 00:03:47,610 I didn't actually initialize my variable. 60 00:03:47,910 --> 00:03:49,290 I just declared it. 61 00:03:49,320 --> 00:03:50,210 OK. 62 00:03:50,220 --> 00:03:52,750 This is called the declaration of evaluation. 63 00:03:52,830 --> 00:03:58,510 Then you actually declare a variable and not initialising get. 64 00:03:58,530 --> 00:04:01,110 This is called declaration of a variable. 65 00:04:01,140 --> 00:04:01,950 OK. 66 00:04:02,430 --> 00:04:11,930 But in the case of number variable valuable as you can see here I declared and assign a value to my 67 00:04:11,940 --> 00:04:12,720 valuable. 68 00:04:12,960 --> 00:04:18,080 Or in other words I declared and initialized my body. 69 00:04:18,250 --> 00:04:18,820 OK. 70 00:04:18,870 --> 00:04:23,760 So this is called declarant and initializing a value. 71 00:04:23,790 --> 00:04:24,320 OK. 72 00:04:24,390 --> 00:04:31,490 So now I'm going to show you how you can actually output the value of your valuables to the console. 73 00:04:31,590 --> 00:04:32,350 OK. 74 00:04:32,550 --> 00:04:38,090 Now I want to output the value of this number variable to the console which is 20. 75 00:04:38,130 --> 00:04:38,840 OK. 76 00:04:39,240 --> 00:04:41,790 So let's see how we can do that. 77 00:04:41,850 --> 00:04:48,880 First we need to actually type in system that out that princeling. 78 00:04:49,130 --> 00:04:49,980 OK. 79 00:04:50,390 --> 00:04:56,480 And then inside Apprentice's we need to put into double codes and then inside the double quotes we need 80 00:04:56,480 --> 00:05:00,980 to actually put in our For example some text. 81 00:05:01,260 --> 00:05:05,670 And then we need to put the semi-colon at the end our statements. 82 00:05:05,700 --> 00:05:10,230 OK so now let's just run our project and see what happens. 83 00:05:10,230 --> 00:05:17,530 So as you can see here it's going to output this text in between these double codes. 84 00:05:17,610 --> 00:05:19,680 Ok to the console area. 85 00:05:19,700 --> 00:05:20,340 OK. 86 00:05:20,450 --> 00:05:23,110 You can access the concert area here. 87 00:05:23,280 --> 00:05:23,920 OK. 88 00:05:24,240 --> 00:05:32,500 So what I don't want just this text I want to actually output the value of this number of variables. 89 00:05:32,570 --> 00:05:33,450 OK. 90 00:05:33,490 --> 00:05:35,060 The de-value is 20. 91 00:05:35,070 --> 00:05:38,310 So how can I access the value of a variable. 92 00:05:38,520 --> 00:05:39,920 So now let me show you. 93 00:05:40,290 --> 00:05:42,770 So not just delete this subtext here. 94 00:05:43,080 --> 00:05:50,960 And in order to access the value of the variable we just need to refer to the name of that variable. 95 00:05:50,970 --> 00:05:51,560 OK. 96 00:05:51,900 --> 00:05:54,360 So this is the data type of value. 97 00:05:54,450 --> 00:05:55,000 OK. 98 00:05:55,200 --> 00:06:01,510 And this is the name of our variable and this is the value that we assigned to our variable. 99 00:06:01,530 --> 00:06:02,440 OK. 100 00:06:03,000 --> 00:06:10,890 So in order to access this value OK this value that you can see here we just need to refer to the name 101 00:06:10,890 --> 00:06:11,730 of that variable. 102 00:06:11,730 --> 00:06:12,600 Which is this. 103 00:06:12,770 --> 00:06:13,480 OK. 104 00:06:13,890 --> 00:06:22,760 So now I just need to type in here number and now I am referring to the name of this variable. 105 00:06:22,950 --> 00:06:31,200 So now if I click on this run button as you can see it's gonna output the value to 20 to the concert 106 00:06:31,200 --> 00:06:31,780 area. 107 00:06:31,890 --> 00:06:32,440 OK. 108 00:06:32,580 --> 00:06:33,550 So that's it. 109 00:06:33,630 --> 00:06:37,220 That's how you can actually access the value of a variable. 110 00:06:37,260 --> 00:06:37,800 OK. 111 00:06:37,890 --> 00:06:42,050 You just need to actually refer to the name of that variable. 112 00:06:42,330 --> 00:06:48,870 And as I said before if you don't have the console window open in your eclipse you just need to click 113 00:06:48,870 --> 00:06:54,860 on this window OK and show you and then click on cancel. 114 00:06:54,870 --> 00:06:55,400 OK. 115 00:06:55,540 --> 00:06:58,350 And now it's going to open the console window for me. 116 00:06:58,350 --> 00:06:59,020 OK. 117 00:06:59,430 --> 00:07:07,950 So another concept that I want to teach you here is that how you can actually use variables and texts 118 00:07:08,400 --> 00:07:09,420 together OK. 119 00:07:09,540 --> 00:07:14,630 For example if you want to go out with some text here it's going to show me an error. 120 00:07:14,700 --> 00:07:20,780 Ok so what's this error syntax error and talk and this text. 121 00:07:20,900 --> 00:07:21,640 Dystocia. 122 00:07:21,720 --> 00:07:28,050 So what should I do in order to output the value of this variable and the text between these two double 123 00:07:28,050 --> 00:07:30,660 quotes to the council area together. 124 00:07:30,740 --> 00:07:31,160 OK. 125 00:07:31,290 --> 00:07:39,150 So if I run my project now it's not showing me a pop up that says errors exist in required projects. 126 00:07:39,170 --> 00:07:42,470 Ok variables proceed with lunch. 127 00:07:42,480 --> 00:07:44,800 No I can't because there is error. 128 00:07:44,970 --> 00:07:50,130 Ok so you can't run your project as you can see here is it's the sign of error. 129 00:07:50,170 --> 00:07:55,020 Ok syntax error on talken the text it is torture. 130 00:07:55,050 --> 00:07:57,500 So what's the solution for this problem. 131 00:07:57,720 --> 00:07:58,320 OK. 132 00:07:58,560 --> 00:08:06,660 So in order to actually concatenate or Linge are valuable and it takes to get there in your programs 133 00:08:07,180 --> 00:08:13,870 you can just actually put a plus operator in between those actually values. 134 00:08:14,100 --> 00:08:17,050 For example as you can see here this is my number variable. 135 00:08:17,160 --> 00:08:18,060 OK. 136 00:08:18,420 --> 00:08:21,600 And I am using a plus operator here. 137 00:08:21,900 --> 00:08:24,770 And then we can actually use our text. 138 00:08:24,780 --> 00:08:30,210 So as you can see the error is gone and now I have I can run my project. 139 00:08:30,210 --> 00:08:32,480 So this is our values. 140 00:08:32,580 --> 00:08:36,420 This is the number 20 is the value of our variable. 141 00:08:36,540 --> 00:08:41,890 So and this text is the text between these two double quotes. 142 00:08:42,030 --> 00:08:48,570 So for example if I just put a space here and run my project now as you can see these two values are 143 00:08:48,570 --> 00:08:49,910 separated now. 144 00:08:50,340 --> 00:08:58,260 So for example if I want to actually concatenate or Linge to text together in my program I can just 145 00:08:58,720 --> 00:09:05,070 delete this number of variable and just put the double quotes and between these two double codes I can 146 00:09:05,070 --> 00:09:07,200 put my values for example values. 147 00:09:07,210 --> 00:09:07,650 OK. 148 00:09:07,680 --> 00:09:11,470 Everything that I want and then just run my project. 149 00:09:11,490 --> 00:09:18,180 And as you can see it's going to show me these values and the space as you can see this is the space 150 00:09:18,180 --> 00:09:19,950 here that I've put. 151 00:09:20,130 --> 00:09:20,650 OK. 152 00:09:21,210 --> 00:09:24,140 And the text between these two double quotes. 153 00:09:24,270 --> 00:09:25,110 OK. 154 00:09:25,620 --> 00:09:29,170 So that's it for concatenation in Java. 155 00:09:29,520 --> 00:09:33,810 So now let me show you another example of concatenation in Java. 156 00:09:34,080 --> 00:09:40,970 So in order to actually output some results to the console I just need to type in here again system 157 00:09:42,140 --> 00:09:49,850 that out that princeling and then inside the parentheses just put the double quotes instead of double 158 00:09:49,850 --> 00:09:51,260 quotes just type in your text. 159 00:09:51,260 --> 00:09:52,320 This is my text. 160 00:09:52,340 --> 00:09:52,490 OK. 161 00:09:52,550 --> 00:09:55,010 This is my example variable.