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These are the user uploaded subtitles that are being translated: 1 00:00:00,880 --> 00:00:05,960 We can use variables to store values in the getting started section, you learn to create and run a 2 00:00:05,980 --> 00:00:10,750 job, a program you ran, a fairly simple program that prints Hello, Java. 3 00:00:12,100 --> 00:00:16,120 Now, one more useful program is able to store information, and that's why in this lesson, you're 4 00:00:16,120 --> 00:00:19,030 going to learn to store values inside variables. 5 00:00:21,940 --> 00:00:27,610 First thing I'll need you to do is create a new Java project by yourself and call it Section two, then 6 00:00:27,610 --> 00:00:28,840 launch it from voice code. 7 00:00:31,700 --> 00:00:37,190 And inside the project, critical name variables Jebba and make sure the variables class has the main 8 00:00:37,190 --> 00:00:37,580 method. 9 00:00:44,870 --> 00:00:46,340 All right, what is a variable? 10 00:00:48,040 --> 00:00:49,780 A variable can store value. 11 00:00:52,060 --> 00:00:57,790 Think of a variable as some kind of box, each variable has a name, so I'll call this one food. 12 00:00:59,240 --> 00:01:02,990 This variable, this quote unquote, box can store values. 13 00:01:04,310 --> 00:01:05,720 This one store is a tax value. 14 00:01:07,360 --> 00:01:13,690 But it can also store an integer value, by the way, integer means hole number, the take home message 15 00:01:13,690 --> 00:01:19,000 is that a variable can store any type of value instead of make a variable in Java, you need to include 16 00:01:19,000 --> 00:01:25,870 three pieces of information, the type of value we can store, the name of the variable and the value 17 00:01:25,870 --> 00:01:26,410 itself. 18 00:01:27,650 --> 00:01:34,400 And to this code creates a variable called people, the variables of type int so we can only store numbers 19 00:01:34,400 --> 00:01:35,600 like the number two. 20 00:01:38,870 --> 00:01:45,140 Some inside main making into variable named people and set it equal to 20 different people. 21 00:01:46,250 --> 00:01:50,210 Is equal to 20 and don't forget your semicolon. 22 00:01:50,870 --> 00:01:53,780 Remember that every line of code in Java needs a semicolon at the end. 23 00:01:53,930 --> 00:01:55,640 Otherwise, your code is not going to run. 24 00:01:56,900 --> 00:01:59,030 And so now this variable stores the number 20. 25 00:02:02,730 --> 00:02:07,500 Now, I want to talk about the convention to naming variables and there's a specific way to name them, 26 00:02:07,500 --> 00:02:09,810 and it's called Lower Kemel case. 27 00:02:12,670 --> 00:02:15,760 In Java, the variable needs to start with a lowercase letter. 28 00:02:17,700 --> 00:02:23,430 The variable people starts with a lower case P, but what if we have more than one word like people 29 00:02:23,430 --> 00:02:24,070 on bus? 30 00:02:24,930 --> 00:02:29,970 In that case, you'll start with a lower case letter, but the words that follow must be upper case. 31 00:02:31,140 --> 00:02:33,510 Notice that people start to they lower case P. 32 00:02:34,350 --> 00:02:36,810 And on bus, half capital letters. 33 00:02:40,120 --> 00:02:45,150 This right here is the lower camel case format, and that's how you're supposed to name variables, 34 00:02:46,180 --> 00:02:51,310 if in my code I decide to rename this variable to people on Busse, I would have to use the lower Camil 35 00:02:51,310 --> 00:02:56,920 case format, people on bus, yet people on buses. 36 00:02:56,920 --> 00:03:02,380 Dulong I prefer saying passengers, so I'll rename the variable to passengers. 37 00:03:03,840 --> 00:03:10,470 Remember to write class names in Camil case, where each word is capitalized and joined together and 38 00:03:10,470 --> 00:03:16,530 always write variable names and lower camel case were the first word is lowercase, but the words that 39 00:03:16,530 --> 00:03:17,970 follow are capitalized. 40 00:03:18,690 --> 00:03:23,310 I highly encourage you to follow these conventions because it's what the professionals do and it makes 41 00:03:23,310 --> 00:03:25,080 your code clearer and easier to read. 42 00:03:28,620 --> 00:03:33,450 OK, so we talked about variables being able to store values, but you can actually print the value 43 00:03:33,450 --> 00:03:34,320 inside a variable. 44 00:03:35,520 --> 00:03:39,240 You created a variable called passengers and it stores the value 20. 45 00:03:40,020 --> 00:03:44,430 So using print line, you can print the variables value to the console system. 46 00:03:48,360 --> 00:03:50,310 Print line passengers. 47 00:03:55,170 --> 00:04:00,930 Now, you can go ahead and open up the terminal, compile your code using job C variables Java. 48 00:04:02,680 --> 00:04:06,100 And run the compiled code using Java variables. 49 00:04:06,970 --> 00:04:09,700 Sure enough, the value inside passengers is 20. 50 00:04:11,620 --> 00:04:16,420 Now, here's a similar code where I didn't name passed in your stores the value five instead of 20, 51 00:04:17,230 --> 00:04:19,600 then you printed the value inside passengers. 52 00:04:24,180 --> 00:04:30,600 Java is strongly typed once you define the valley type or verbal can only store values of that type. 53 00:04:31,560 --> 00:04:37,680 For example, you cannot stop text in an integer variable that's illegal, the value that you store 54 00:04:37,680 --> 00:04:39,930 needs to be consistent with the variable type. 55 00:04:41,370 --> 00:04:45,400 You try to store value that is different from the variable type, you will get a type mismatch. 56 00:04:46,540 --> 00:04:48,820 In other words, your codes not going to compile. 57 00:04:51,390 --> 00:04:55,800 So back to my code, I'm going to try to set passengers equal to some. 58 00:04:57,140 --> 00:04:58,700 Text value. 59 00:05:01,470 --> 00:05:02,840 Let's try to Kampala's. 60 00:05:08,200 --> 00:05:13,810 And I get an error in line three of my code and it says that string cannot be converted to it. 61 00:05:15,040 --> 00:05:18,700 This error is a result of trying to store text in an integer variable. 62 00:05:20,130 --> 00:05:24,900 And invariable can only store integer values like five, you cannot store text. 63 00:05:27,600 --> 00:05:33,900 So compiling this code and running it were good, by the way, in case you forgot, the reason I'm able 64 00:05:33,900 --> 00:05:39,180 to run these terminal commands so quick is because I'm using the up key to access previous terminal 65 00:05:39,180 --> 00:05:39,810 commands. 66 00:05:40,680 --> 00:05:44,850 You would have already seen this in the workbook one point one, as well as your very first quests. 67 00:05:46,750 --> 00:05:52,360 In any case, Java is case sensitive, which means Java discriminates between uppercase and lowercase 68 00:05:52,360 --> 00:05:57,610 letters, for example, passengers is not the same as capital passengers. 69 00:06:00,510 --> 00:06:05,730 I try to compile this, I would get an error in line four of my code and it tells me that Java does 70 00:06:05,730 --> 00:06:09,310 not recognize the variable capital passengers because you never made one. 71 00:06:09,720 --> 00:06:12,320 You must always stay consistent with letter cases. 72 00:06:12,990 --> 00:06:15,340 So we're going to fix this variable back to what it was. 73 00:06:16,470 --> 00:06:17,070 All right. 74 00:06:20,940 --> 00:06:26,700 Finally, you can set variables equal to each other if you set a variable equal to another, the variable 75 00:06:26,700 --> 00:06:30,240 copies of the value inside the first one, just like you're seeing here. 76 00:06:33,650 --> 00:06:38,960 So make an integer variable name bus tickets, remember that you need to write variables in lower camil 77 00:06:38,960 --> 00:06:44,760 case lower case B in the words that follow must be upper case bus tickets. 78 00:06:45,920 --> 00:06:49,650 Now, let's assume to enter the bus, every passenger needs one bus ticket. 79 00:06:50,330 --> 00:06:57,560 So there are as many bus tickets as there are passengers and bus tickets is equal to passengers. 80 00:07:01,760 --> 00:07:07,300 Now we're going to check the value inside bus tickets by printing it system dot out, dot print line 81 00:07:07,300 --> 00:07:15,040 bus tickets, I would expect this to print five, but let's double check Gervasi variables that Gever. 82 00:07:17,650 --> 00:07:23,720 Job of variables and as expected, it prints five bus tickets and five passengers. 83 00:07:24,790 --> 00:07:25,490 Great. 84 00:07:25,510 --> 00:07:27,160 Here's the code we have so far. 85 00:07:30,470 --> 00:07:34,970 By setting the bus tickets variable equal to passengers, it copies the value inside. 86 00:07:40,570 --> 00:07:46,210 In this lesson, you learn to store values inside variables, you stored the integer value five inside 87 00:07:46,210 --> 00:07:49,990 passengers and then you print it out using the print online function. 88 00:07:52,200 --> 00:07:55,320 You also learn that variables can only store values of their type. 89 00:07:56,220 --> 00:07:59,250 For example, you cannot store text in an integer variable. 90 00:08:00,330 --> 00:08:03,570 The last thing you learned was the set variables equal to each other. 91 00:08:04,350 --> 00:08:08,640 You set the bus ticket variable equal to passengers and it copied the value inside. 9687

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