ข้อมูลในบทความนี้จะพูดถึงint to double java หากคุณกำลังมองหาint to double javaมาถอดรหัสหัวข้อint to double javaกับSelf Directed CEในโพสต์Java Tutorial – 03 – Read Integers and Doubles from Keyboard with Scannerนี้.
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ภาพรวมของเนื้อหาที่เกี่ยวข้องint to double javaที่แม่นยำที่สุดในJava Tutorial – 03 – Read Integers and Doubles from Keyboard with Scanner
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คำอธิบายเกี่ยวกับหมวดหมู่int to double java
ดูบทเรียนเพิ่มเติมในลักษณะนี้ได้ที่ เรียนรู้วิธีอ่านข้อมูลประเภทอื่นๆ จากแป้นพิมพ์ เช่น ทศนิยมทศนิยม เลขคู่ และจำนวนเต็มโดยใช้วิธีการสแกนในภาษาจาวา
ภาพถ่ายบางส่วนที่เกี่ยวข้องกับหัวข้อของint to double java
นอกจากการหาข่าวเกี่ยวกับบทความนี้แล้ว Java Tutorial – 03 – Read Integers and Doubles from Keyboard with Scanner คุณสามารถดูและอ่านบทความเพิ่มเติมด้านล่าง
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แท็กที่เกี่ยวข้องกับint to double java
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Java Tutorial – 03 – Read Integers and Doubles from Keyboard with Scanner.
int to double java.
หวังว่าค่านิยมบางอย่างที่เรามอบให้จะเป็นประโยชน์กับคุณ ขอขอบคุณสำหรับการดูเนื้อหาint to double javaของเรา
Thanks a loooooot🤍🤍🤍
My notes (meat of the lesson is 15 min then the rest are details, examples and review)
0:22 Going from reading a single character/byte from keyboard input to a whole integer/decimal.
2:45 To read said numbers we are going to use Scanner Class.
4:34 Review of what a Class is (A CLASS IS A TEMPLATE) an analogy with cars and it's parts.
7:25 Creating Objects from the Class which is a template that's already created for you this case the Scanner Class.
7:45 This line "import java.util.Scanner" imports that Scanner Class.
7:54 First step is we need to do is create an instance of that Scanner Class so we can use it to read from the keyboard
meaning we want to "create an object from the scanner class so that we can then use it".
Scanner keyboardInput; //we can leave it here and we have created an Object from the Scanner Class.
[Scanner keyboardInput = new Scanner(System.in);] // this is how you create Objects from classes in Java not only for Scanner Class.
[
Scanner- this is the general class, scanner class
KeyboardInput – this is the name of the object that you are creating
new Scanner – we have to assign something to the left side so we create a new Scanner Object
(System.in) – so this scanner object is reading stuff in from System.in which is the keyboard.
]
9:55 When you create an object the thing comes into existance with a constructor (the right hand side is a constructor)
10:30 analogy with int and Scanner (left side) ["Int keyboard Input" similar to "Scanner keyboardInput"]
10:55 new Scanner(System.in)- new keyword creates the object of Scanner type and everything is coming from the keyboard.
11:22 We setup an int and a print statement to prepare to receive an integer from the keyboard
12:05 We gonna use now the Scanner object that we have created called keyboardInput to do that for us.
12:20 When you create objects like this they are gonna have methods associated with them. So when you
create a class you define methods that make sense for the class, in this case we need some methods
to read stuff from the keyboard, so the main method we gonna use here is:
[keyboard Input.nextInt();]
[
keyboardInput -is the scanner object that we have created
. – the dot says we're using a method from that class
nextInt() is one of the methods of the scanner class
nextInt() – means we are reading the next integer
]
So when we've created this object then the nextInt methods is automatically available to be used.
13:07 Now we just make the above equal to our int variable called test that we created earlier so we can store it:
test = keyboard Input.nextInt();
14:28 We can use that stored variable anywhere in our program in for loops if statements, to calculate things etc (example in video)
tip: he copied the same test = keyboardInput.nextInt(); twice , since he is just demostrating he didn't create a new int varibale or a new object
so that he could store the first input from the keyboard and then the next input.
PART 2 READING DECIMALS:
16:25 Now dealing with decimal inputs instead of integers, but basically you just change every into into a double and call it a day it's the same.
PART 3 AVOIDING ERRORS DURING THE READ with the method ".hasNextInt()" in this case or in other cases ".hasNextDouble()":
20:55 We only want to do the read when we know that there's an integer waiting at the keyboard only then we do the read so we put an if statement
if(keyboardInput.hasNextInt() == true) integerNumber = keyboardInput.nextInt();
this line does the read : [integerNumber = keyboardInput.nextInt()]
22:24 make sure to initialize the int variable that is being used to store from the keyboard cause when the program starts it doesn't know what
to do with that variable since the keyboard input hasn't been written yet, because it is inside an if statement Java doesn't know what to do with it.
So if you want some sort of error trapping to prevent prolems you need to use the if statement.
23:50 Review of the important methods inside the Scanner Class:
nextInt() – this one reads the next integer from the keyboard
nextDouble() – this one read the next floating point number from the keyboard
hasNextInt() – this one returns true or false depending if there's an integer there or not
hasNextDouble() – this checks to see if there's a decimal number there
24:37 Example with hasNextDouble()
25:35 General Summary, bottom line is when you're reading from a keyboard you need to remember 3 things:
1. [import java.util.Scanner;] – will give us access to scanner class which has already been created from you.
2. ["Scanner keyboardInput"] create an object of type scanner
we want to associate the above with a new scanner object "= new Scanner(System.in);"
3.So now that we have this scanner object defined (left side), we can access all the methods of the scanner class:
["integerNumber = keyboardInput.nextInt();" ]
this method .nextInt does the reading and we assign that to the variable we created (left side)
We have done a similar thing in lesson 19 vol 1 called Math class.
i made a little calculator 😛
Scanner keyboardInput = new Scanner(System.in);
int number1, number2, answer;
System.out.println("Enter first number: ");
number1 = keyboardInput.nextInt();
System.out.println("Enter second number: ");
number2 = keyboardInput.nextInt();
answer = number1 + number2;
System.out.println("Answer: " + answer);
answer = keyboardInput.nextInt();
Hello,
I really want to thank you for the JAVA course, you are really clear in your explanations, and I am very pleased.
There's one thing you did not really refer to in this lesson and that is how to close the SCANNER.
I would love if you would address this, I admit it belongs to the more advanced part but would be nice if it had an explanation as well (I just really like your explanations)
Thanks
What Really Happened in Afghanistan, The Untold Story 👇
https://www.youtube.com/watch?v=JKQF-Iic3kI
he sounds like the khan academy guy
seriously just shut up and start the lesson
12:13 Int input
17:34 Double input
what if i want to input in the integer with percentage?
Thank you!
Amazing! Thanks!
Thanks for your kindness , its really inspired me , helpful for our generation💕
you shoud make a book
because you the best
you the best
Hello,
First I wanted to say THANK YOU, I love your videos on Java, you are very clear and really easy to understand the concept. so thank. you. I am interested on watching your videos in order, do you have any suggestions on which videos to starts with, I started on Java Tutorial from 2018 but I only got to #12 and then I couldn't find what was next, any tips on how to follow the videos? Thank you
I've watched all of volume 1 and now i'm on vol 2. It's been great and I fell like I am really learning, until I got to this video and I'm completely lost. I don't understand it at all.
hello, i wrote down following code:
import java.util.Scanner;
public class EserciziCap2_6_2 {
public static void main(String[] args) {
Scanner aaa = new Scanner (System.in);
System.out.println("inserire x");
Double x = aaa.nextDouble();
System.out.println(x);
}
}
and it returns mutliple error messages:
Exception in thread "main" java.util.InputMismatchException
at java.base/java.util.Scanner.throwFor(Scanner.java:939)
at java.base/java.util.Scanner.next(Scanner.java:1594)
at java.base/java.util.Scanner.nextDouble(Scanner.java:2564)
at EserciziCap2_6_2.main(EserciziCap2_6_2.java:11)
all other string methods works (nextInt, next, nextLine), just nextDouble is giving me messes. what's is wrong?? thanks
Hi I'm new to java and was just wondering I how i could enter a number say 1 and then get the response back "BMW"
Is there a way to get all the tutorials in one folder? You have a lot of videos on your channel
YOU ARE THE BEST