#83 User Input using BufferedReader and Scanner in Java

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Telusko

Telusko

Жыл бұрын

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In this lecture we are discussing about different ways to take input in java:
how to take input from user :
in C++ we use cin
in C we use scanf()
in python we use input()
How to take input in java?
#1
using System.in.read()
-- using System.in.read() we can take single character input only, if we provide multiplecharacterr
itconsidersr the firstcharacterr of enter sequence.
-- if we want to show result of multiple character we can use loop (not in video lecture forcuriosityy)
e.g
class Main{
public static void main(String[] args) throws Exception{
int i =System.in.read(); // read a byte from the keyboard
System.out.println(i); // print the byte value
/*
input: a
output: 97
input: A
output: 65
input: 345 /considere 3 digit from number
output: 51
input: 3456 //consider 3 digit from number
output: 51
input: 3
output: 51
return ascii value of the input
*/
// to get actual number
// 1. convert ascii value to char
System.out.println((char)i); // print the char value
// 2. subtract 48 from the ascii value
System.out.println(i-48); // print the actual number
//but it is only for single digit number
// formultiple-digittnumbersr we have to use loop
// 3. use loop
int n=0;
while(i!=13){ // 13 is ascii value of enter key
n=n*10+(i-48);
i=System.in.read();
}
System.out.println(n);
}
}
using InputStreamReader class:
In Java, the InputStreamReader class is used to read data from an input stream and convert it into characters.
It is often used with the BufferedReader class, which provides a buffered way to read characters from an input stream.
e.g
class Main{
public static void main(String[] args) {
BufferedReader br = null;
try {
// create a new InputStreamReader to read from System.in
InputStreamReader isr = new InputStreamReader(System.in);
// create a new BufferedReader to read from the InputStreamReader
br = new BufferedReader(isr);
System.out.println("Enter your name:");
// read a line of text from the BufferedReader
String name = br.readLine();
System.out.println("Hello, " + name + "!");
} catch (IOException e) {
System.err.println("Error reading input: " + e.getMessage());
}
finally{
if(br!=null){
try{
br.close();
}
catch(IOException e){
System.out.println("There might some problem to closing the resource");
}
}
}
}
}
Note: if open the resource then close is important
Use of Scanner Class :
To make programmer life easy
Scanner class was introduced in Java 1.5 as part of the Java API to provide an easy way
to read user input from various sources such as the keyboard.
a) Reading input through keyboard:
-- import java.util.Scanner; need to import in java file
Scanner scanner = new Scanner(System.in);
System.out.print("Enter your name: ");
String name = scanner.nextLine();
System.out.println("Hello, " + name + "!");
-- Scanner object using the System.in input stream, which represents the keyboard.
We then use the nextLine() method to read a line of text entered by the user.
Important: From here this part is not in video, for your cursoity we are put only in this description.
b) read through file
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
File file = new File("input.txt");
try {
Scanner scanner = new Scanner(file);
while (scanner.hasNextLine()) {
String line = scanner.nextLine();
System.out.println(line);
}
} catch (FileNotFoundException e) {
System.out.println("File not found: " + e.getMessage());
}
we create a Scanner object using a File object that represents the input file.
We then use the hasNextLine() and nextLine() methods to read each line of text from the file.
c) Read input though String
import java.util.Scanner;
String input = "156 2 3 4 5";
Scanner scanner = new Scanner(input);
while (scanner.hasNextInt()) {
int number = scanner.nextInt();
System.out.println(number);
}
-- Scanner object using a String object that contains the input. We then use the hasNextInt() and nextInt() methods to read each integer from the string.
Github repo : github.com/navinreddy20/Javac...

Пікірлер: 54
@sanchitbajpaiexp7504
@sanchitbajpaiexp7504 11 күн бұрын
Really appreciate the way you taught this concept. Going through each of the class, methods, constructors and showing their implementations. I have never seen someone depicting the whole idea behind BufferedReader before. Thanks for this.
@student_03
@student_03 11 ай бұрын
thanks a lot no useless talk to the point, crisp short lecture does the job
@mowafkmha4505
@mowafkmha4505 Жыл бұрын
you deserve more views diving really deep into some details that helps to better understand makes you really special from any other channel, I think I found a treasure here
@yashaswinihm4288
@yashaswinihm4288 6 ай бұрын
And the beauty is.. I selected the best playlist to learn java😊.
@tiwarikartikeya
@tiwarikartikeya 2 ай бұрын
Such clarity and beautiful explanation. You have always been my goto person when I need to understand something which I know I cannot understand from any other video. You are awesome.
@nononnomonohjghdgdshrsrhsjgd
@nononnomonohjghdgdshrsrhsjgd 7 ай бұрын
Wonderful channel. You are one of the few people, which organize his courses in such a way, that i can quickly see in which series, a video is in.
@nononnomonohjghdgdshrsrhsjgd
@nononnomonohjghdgdshrsrhsjgd 7 ай бұрын
What does "x:" and "a:" mean in Java in System.out.println(x:"Hello")?
@kingkooper4627
@kingkooper4627 6 ай бұрын
best channel of the century 🎉🎉
@TheWildStatistician
@TheWildStatistician 6 ай бұрын
Going into insane detail! Well done!
@jellyjollyjelly9513
@jellyjollyjelly9513 7 ай бұрын
precise and on point! love ur style
@d0msch326
@d0msch326 18 күн бұрын
Great explanation and good examples. Thank you for this good and on point lecture.
@ferfykins
@ferfykins Жыл бұрын
Ty for the video!!! Can scanner class be used with other resources besides command line input? for example a text file, or network input?
@milehighgarage
@milehighgarage Ай бұрын
Great explainer -- tight -- all the best Sir
@michaelp.channel331
@michaelp.channel331 14 күн бұрын
I love your explanation
@sonamohialdin3376
@sonamohialdin3376 Жыл бұрын
Very helpful tutorial
@mf3396
@mf3396 10 ай бұрын
Amazing class
@_adarsh_raj_pathak_
@_adarsh_raj_pathak_ Жыл бұрын
Thanks for such deep dive in the class>object>class>method🦖 Hats Off to your way of explanation 🔥
@Trading_Club007
@Trading_Club007 8 ай бұрын
can anyone explain why out is defined null and how it is working with null because when i write this program by classes and calling it in main, it gives an java.lang.NullPointerException
@sakthipriya8653
@sakthipriya8653 10 ай бұрын
In the description, File file = new file("input.txt") Should'nt this line be given inside try?
@parthisanjay3252
@parthisanjay3252 3 ай бұрын
So out is a PrintStream type of reference initiated with null, then how it is used to calling println( ) which is a non static method right we need to create a object of PrintStream class so that we can access any non static members in that class
@varadavinay719
@varadavinay719 9 ай бұрын
10:12 😂😂😂 love your teaching man
@maleeshasandakalum6213
@maleeshasandakalum6213 11 ай бұрын
Thank you sir❤❤
@Suresh_edits679
@Suresh_edits679 Жыл бұрын
nice sir
@alladiakhil7425
@alladiakhil7425 Жыл бұрын
We are not getting the videos in order can you please rearrange it
@chandangouda6866
@chandangouda6866 7 ай бұрын
Which compiler are you using
@saqibafridi5292
@saqibafridi5292 9 ай бұрын
Yes Elian ! I am waiting why you keep this video in #83 and i jumped from #13 video direct to #83 hahahahah
@nikkg7055
@nikkg7055 Жыл бұрын
one more method PrintWriter..?
@anshsahu8290
@anshsahu8290 11 ай бұрын
Ascii or utf16 🤔
@yt-1161
@yt-1161 Жыл бұрын
thumbs up
@darswayeeyou
@darswayeeyou 10 ай бұрын
is out an object or object reference?
@Trading_Club007
@Trading_Club007 8 ай бұрын
it is an object BTW what is object reference
@syedadil7256
@syedadil7256 Жыл бұрын
Better to use Scanner class right sir?
@ankushdhull7312
@ankushdhull7312 Жыл бұрын
yes....scanner class is far better than bufferedReader class!!
@vinayv6729
@vinayv6729 Жыл бұрын
@@ankushdhull7312 but scanner class is very slow
@syedadil7256
@syedadil7256 Жыл бұрын
@@vinayv6729 who cares bro... we need shortcuts
@vinayv6729
@vinayv6729 Жыл бұрын
@@syedadil7256 maybe but it does matter in cp.
@shua_the_great
@shua_the_great 2 ай бұрын
8:54 Telusko casually signaling he's part of the illuminati Love the videos btw
@myvoice7558
@myvoice7558 Жыл бұрын
wow
@yeeshraj887
@yeeshraj887 Жыл бұрын
Can anyone tell which IDE is this?
@hemalathatummalapalli4636
@hemalathatummalapalli4636 Жыл бұрын
Intellij ide
@yeeshraj887
@yeeshraj887 Жыл бұрын
@@hemalathatummalapalli4636 Thank u
@nishant_singh
@nishant_singh Жыл бұрын
Its VS code not Intellij
@ayushpandit_571
@ayushpandit_571 10 ай бұрын
​@@hemalathatummalapalli4636kya code krega re tu 😂😂
@sidhiqvs9227
@sidhiqvs9227 2 ай бұрын
Scanner was introduced in java 1.5 People before java 1.5 😅😅
@nishant_singh
@nishant_singh 11 ай бұрын
Buffer reader works faster than scanner...
@raghavkaushik7266
@raghavkaushik7266 7 ай бұрын
In python just write input() done.
@yenaremadun7184
@yenaremadun7184 7 ай бұрын
but python is slow. There is always a trade off
@Progamer-fq8st
@Progamer-fq8st 4 ай бұрын
@@yenaremadun7184 in C++ you just write cin LOL
@charanmc4484
@charanmc4484 Жыл бұрын
rip Buffer reader 💀🐿️😅
@techfreak8854
@techfreak8854 9 ай бұрын
Do bufferreader still work?
@saurabh1087
@saurabh1087 9 ай бұрын
BufferedReader is faster than Scanner
@naqibullahsultan4958
@naqibullahsultan4958 3 ай бұрын
just waste people time
@srimantamondal8769
@srimantamondal8769 Жыл бұрын
Really appreciate the way you taught this concept. Going through each of the class, methods, constructors and showing their implementations. I have never seen someone depicting the whole idea behind BufferedReader before. Thanks for this.
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