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Enhanced For Loop5:14 with Craig Dennis
Let's explore how to loop through all elements in the array using a for each approach.
[MUSIC] 0:00 So now we have a single variable that can store multiple elements. 0:04 We can pass that variable around, store it as a field on an object, but then what? 0:08 In your coding journey, you'll find that one of the most common tasks in 0:12 programming involves looping through your data. 0:16 You'll process each and every value in your data. 0:18 Arrays are wonderful to use for loops. 0:21 So let's go get familiar with them. 0:24 All right, so let's get coding. 0:26 I have attached a new work space here and there is a file called Explore.java. 0:28 It's got the main boiler plate 0:33 Java application program already written for you. 0:36 You're welcome. 0:39 So let's take our same movie theater example 0:40 of getting all these friends together. 0:43 Let's imagine for a second that group texting doesn't exist because I'm old, and 0:45 I still use one of those flip phones. 0:49 But I wanna send everyone a text with the movie showtime. 0:51 So let's do this, let's recreate that friends array here. 0:54 Well, actually, why don't you do it? 0:58 Why don't you use the shortcut method that you can do when declaring and 1:00 initializing in a single line. 1:04 Here, let's do this, I'll type out the instructions, let's see. 1:06 Create a new friends array using the array literal shortcut. 1:10 Include Ben, Alena, and Pasan. 1:18 Okay, pause me, do it and then unpause me to review how I did it. 1:26 Ready? 1:30 How did you do? 1:32 Here's what I did. 1:33 Made a new string array called friends and 1:35 I added Ben, Alena and Pasan. 1:41 So we want to basically write a personalized text message to each person 1:49 in our friends array. 1:53 We'll just write out to the console, but you get the idea. 1:55 Would you wanna process every element in the array, a great solution to reach for 1:58 is the enhanced for loop. 2:03 The way the enhanced for loop works is pretty straight forward, so 2:05 first you type the keyword, for. 2:09 Now much like if statements, for 2:12 statements are followed by an expression which is surrounded by parenthesis. 2:14 And then after you've defined your expression, again, 2:19 much like an if statement, you open your block of code with a curly brace and 2:22 close it with a closing curly brace. 2:26 In the enhanced for form, the expression is pretty clean and clear. 2:29 So what you do first is you declare a new 2:34 variable that you would like to use within your code block. 2:37 So we're gonna call that String friend. 2:41 And then we're gonna prep the colon and then friends. 2:45 So this can be read as for each friend in friends. 2:51 Processing each element of a collection like this is known as iterating. 2:57 And we are iterating over our friends array. 3:01 An array is able to be iterated on. 3:05 Or more commonly stated, arrays are iterable. 3:07 The way that the enhanced for loop works is that anything that you place over here 3:11 on the right side must be iterable. 3:16 We'll get into how to ensure that in a future course but for 3:19 now just know that arrays meet that criteria, they are iterable. 3:23 So, now that we have each element in the array available on each 3:27 iteration though this loop, we can use it. 3:32 So let's send our pretend text to each of our friends so, 3:35 let's just use a formatted string, right? 3:40 So let's say System.out.printf, 3:43 let's see, hey %s, the movie starts at 7. 3:49 And remember these flip phones are hard to type on, so 3:55 I'm just gonna do a C, and a U, and there. 3:58 All right, and then we're gonna do a new line, %n, cool. 4:00 I'm gonna pass in friend, right? 4:04 Cuz that's what we want to go in where that %s is. 4:10 So again, 4:13 this friend here is being changed on each iteration through the loop. 4:14 Each and every string in this array will run. 4:20 Here, so let's run it. 4:22 So what we'll do is we'll make sure that this is saved. 4:23 And we'll say clear. 4:27 And javac Explore.java, 4:28 don't need to do that clear but I like to clear the console before hand. 4:32 And java Explore, and then that way we can use the up arrow. 4:37 There we go. We should see, there we go, hey Ben, 4:41 hey Alena, hey Pasan. 4:45 Awesome, so this is pretty clear and concise, isn't it? 4:47 When you need to process all items in an array, this enhanced for loop is the way 4:52 to go, and it is the recommended approach because of how clear it is, right? 4:57 Now you probably notice that this is called the enhanced for loop. 5:03 So what is this unenhanced for loop then? 5:07 Well, it's just called a for loop, and let's take a look at that next. 5:10
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