I am trying to count carriage return occurrences within string input. I tried both Scanner and BufferedReader. With Scanner, nextLine() does not pick up Carriage Returns. next() with Scanner looks for tokens, such as a space in input, and token splits up the input. I want the entire input to be read as single input. This probably means I cannot use Scanner.
With BufferedReader, readLine() reads up to a Carriage Return, but does not return a Carriage Return in input. If I use "reader.read();" then it tells me that the variable user_input HAS to be int. user_input is supposed to be a string input that MAY have an integer, but it also may not. The only thing is that program would continue until input contains "/done". I would appreciate it if somebody would simply point me in the right direction!
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
String user_input = "";
System.out.println("Enter a string: ");
while (!user_input.contains("/done")) {
user_input = reader.readLine(); //cannot be readLine because it only reads up to a carriage return; it does NOT return carriage return
//*Sadly, if I use "reader.read();" then it tells me that user_input HAS to be int. user_input is a string input
String input = user_input;
char[] c = input.toCharArray();
int[] f = new int[114];
System.out.println("Rest of program, I convert input to ascii decimal and report the occurences of each char that was used");
}
catch (IOException e) {
e.printStackTrace();
}
}
Is this what you're looking for?
Scanner scanner = new Scanner(System.in);
scanner.useDelimiter("\\z"); //"\\z" means end of input
String input = scanner.next();
EDIT: If you want the "\n" to show as "CR", just do this:
input.replaceAll("\\n", "CR");
There's a library called StringUtils that can do this very easily. It has a method named countMatches. Here's how you can use it. But first, you should combine your input into one string:
package com.sandbox;
import org.apache.commons.lang.StringUtils;
public class Sandbox2 {
public static void main(String[] args) {
String allInput = "this\nis\na\n\nfew\nlines\nasdf";
System.out.println(StringUtils.countMatches(allInput, "\n"));
}
}
This outputs "6".
Read characters one by one until EOF is encountered using read() method.
JAVA DOCS
read() in java reads any character(even \n, \r or \r\n). Thus read character one by one and check whether the character read in "Carriage return" or not.
If yes, then increase the counter.
Related
I'm trying to progress displaying a file line by line with an Enter key, but the if statement that I try doesn't seem to work. If I disregard the if statement, it works, but it feels incomplete because then I'm asking for input and doing nothing with it.
This is what I have:
import java.util.Scanner;
import java.io.*;
public class LineByLine {
public static void main(String[] args) throws IOException {
Scanner in = new Scanner(System.in);
System.out.println("What is the filename?");
String input = in.nextLine();
BufferedReader buff = new BufferedReader(new FileReader(input));
String sen = buff.readLine();
System.out.println(sen);
Scanner enter = new Scanner(System.in);
while (sen != null){
String output = enter.next();
if (output.equals("")){
System.out.println(sen = buff.readLine());
}
}
}
}
I just don't know why my if statement doesn't work.
The core issue is that you misunderstand Scanner and its default configuration: Out of the box, scanner splits on any amount of whitespace. .next() asks for the next token; a token is the thing that appears in between the whitespace.
Thus, pressing enter 500 times produces zero tokens. After all, tokens are what's in between the separator, and the default separator is 'any amount of whitespace'. Pressing enter a bunch of time is still just you entering the same separator.
The underlying problem is that most people appear to assume that Scanner reads one line at a time. It doesn't do that. At all. But you want it to. So, tell it to! Easy peasy - make scanner do what you already thought it did:
Scanner in = new Scanner(System.in);
in.useDelimiter("\\R"); // a single enter press is now the separator.
You should also stop using nextLine on scanners. nextLine and any other next call do not mix. The easiest way to solve this problem is to only ever use nextLine and nothing else, or, never use nextLine. With the above setup, .next() gets you a token which is an entire line - thus, no need for nextLine, which is good news, as nextLine is broken (it does what the spec says it should, but what it does is counterintuitive. We can debate semantics on whether 'broken' is a fair description of it. Point is, it doesn't do what you think it does).
Also, while you're at it, don't make multiple scanners. And, to improve this code, resources must be properly closed. You're not doing that. Let's use try-with, that's what it is for.
public static void main(String[] args) throws IOException {
Scanner in = new Scanner(System.in);
in.useDelimiter("\\R");
System.out.println("What is the filename?");
String input = in.next();
try (BufferedReader buff = new BufferedReader(new FileReader(input))) {
String sen = buff.readLine();
System.out.println(sen);
while (sen != null){
enter.next(); // why does it matter _what_ they entered?
// as long as they pressed it, we're good, right? Just ignore what it returns.
System.out.println(sen = buff.readLine());
}
}
}
I am trying to find a way to take a char input from the keyboard.
I tried using:
Scanner reader = new Scanner(System.in);
char c = reader.nextChar();
This method doesn't exist.
I tried taking c as a String. Yet, it would not always work in every case, since the other method I am calling from my method requires a char as an input. Therefore I have to find a way to explicitly take a char as an input.
Any help?
You could take the first character from Scanner.next:
char c = reader.next().charAt(0);
To consume exactly one character you could use:
char c = reader.findInLine(".").charAt(0);
To consume strictly one character you could use:
char c = reader.next(".").charAt(0);
Setup scanner:
reader.useDelimiter("");
After this reader.next() will return a single-character string.
There is no API method to get a character from the Scanner. You should get the String using scanner.next() and invoke String.charAt(0) method on the returned String.
Scanner reader = new Scanner(System.in);
char c = reader.next().charAt(0);
Just to be safe with whitespaces you could also first call trim() on the string to remove any whitespaces.
Scanner reader = new Scanner(System.in);
char c = reader.next().trim().charAt(0);
There are three ways to approach this problem:
Call next() on the Scanner, and extract the first character of the String (e.g. charAt(0)) If you want to read the rest of the line as characters, iterate over the remaining characters in the String. Other answers have this code.
Use setDelimiter("") to set the delimiter to an empty string. This will cause next() to tokenize into strings that are exactly one character long. So then you can repeatedly call next().charAt(0) to iterate the characters. You can then set the delimiter to its original value and resume scanning in the normal way!
Use the Reader API instead of the Scanner API. The Reader.read() method delivers a single character read from the input stream. For example:
Reader reader = new InputStreamReader(System.in);
int ch = reader.read();
if (ch != -1) { // check for EOF
// we have a character ...
}
When you read from the console via System.in, the input is typically buffered by the operating system, and only "released" to the application when the user types ENTER. So if you intend your application to respond to individual keyboard strokes, this is not going to work. You would need to do some OS-specific native code stuff to turn off or work around line-buffering for console at the OS level.
Reference:
How to read a single char from the console in Java (as the user types it)?
You can solve this problem, of "grabbing keyboard input one char at a time" very simply. Without having to use a Scanner all and also not clearing the input buffer as a side effect, by using this.
char c = (char)System.in.read();
If all you need is the same functionality as the C language "getChar()" function then this will work great. The Big advantage of the "System.in.read()" is the buffer is not cleared out after each char your grab. So if you still need all the users input you can still get the rest of it from the input buffer. The "char c = scanner.next().charAt(0);" way does grab the char but will clear the buffer.
// Java program to read character without using Scanner
public class Main
{
public static void main(String[] args)
{
try {
String input = "";
// Grab the First char, also wait for user input if the buffer is empty.
// Think of it as working just like getChar() does in C.
char c = (char)System.in.read();
while(c != '\n') {
//<do your magic you need to do with the char here>
input += c; // <my simple magic>
//then grab the next char
c = (char)System.in.read();
}
//print back out all the users input
System.out.println(input);
} catch (Exception e){
System.out.println(e);
}
}
}
Hope this helpful, and good luck! P.S. Sorry i know this is an older post, but i hope that my answer bring new insight and could might help other people who also have this problem.
This actually doesn't work:
char c = reader.next().charAt(0);
There are some good explanations and references in this question:
Why doesn't the Scanner class have a nextChar method?
"A Scanner breaks its input into tokens using a delimiter pattern", which is pretty open ended. For example when using this
c = lineScanner.next().charAt(0);
for this line of input
"(1 + 9) / (3 - 1) + 6 - 2"
the call to next returns "(1", c will be set to '(', and you'll end up losing the '1' on the next call to next()
Typically when you want to get a character you would like to ignore whitespace. This worked for me:
c = lineScanner.findInLine("[^\\s]").charAt(0);
Reference:
regex to match a single character that is anything but a space
The best way to take input of a character in Scanner class is:
Scanner sca=new Scanner(System.in);
System.out.println("enter a character");
char ch=sca.next().charAt(0);
You should use your custom input reader for faster results instead of extracting first character from reading String.
Link for Custom ScanReader and explanation: https://gist.github.com/nik1010/5a90fa43399c539bb817069a14c3c5a8
Code for scanning Char :
BufferedInputStream br=new BufferedInputStream(System.in);
char a= (char)br.read();
There are two approaches, you can either take exactly one character or strictly one character.
When you use exactly, the reader will take only the first character, irrespective of how many characters you input.
For example:
import java.util.Scanner;
public class ReaderExample {
public static void main(String[] args) {
try {
Scanner reader = new Scanner(System.in);
char c = reader.findInLine(".").charAt(0);
reader.close();
System.out.print(c);
} catch (Exception ex) {
System.out.println(ex.getMessage());
}
}
}
When you give a set of characters as input, say "abcd", the reader will consider only the first character i.e., the letter 'a'
But when you use strictly, the input should be just one character. If the input is more than one character, then the reader will not take the input
import java.util.Scanner;
public class ReaderExample {
public static void main(String[] args) {
try {
Scanner reader = new Scanner(System.in);
char c = reader.next(".").charAt(0);
reader.close();
System.out.print(c);
} catch (Exception ex) {
System.out.println(ex.getMessage());
}
}
}
Suppose you give input "abcd", no input is taken, and the variable c will have Null value.
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
Scanner reader = new Scanner(System.in);
char c = reader.next(".").charAt(0);
}
}
To get only one character char c = reader.next(".").charAt(0);
import java.util.Scanner;
public class userInput{
public static void main(String[] args){
// Creating your scanner with name kb as for keyBoard
Scanner kb = new Scanner(System.in);
String name;
int age;
char bloodGroup;
float height;
// Accepting Inputs from user
System.out.println("Enter Your Name");
name = kb.nextLine(); // for entire line of String including spaces
System.out.println("Enter Your Age");
age = kb.nextInt(); // for taking Int
System.out.println("Enter Your BloodGroup : A/B/O only");
bloodGroup = kb.next().charAt(0); // For character at position 0
System.out.println("Enter Your Height in Meters");
height = kb.nextFloat(); // for taking Float value
// closing your scanner object
kb.close();
// Outputting All
System.out.println("Name : " +name);
System.out.println("Age : " +age);
System.out.println("BloodGroup : " +bloodGroup);
System.out.println("Height : " +height+" m");
}
}
Try this:
char c=S.nextLine().charAt(0);
// Use a BufferedReader to read characters from the console.
import java.io.*;
class BRRead {
public static void main(String args[]) throws IOException
{
char c;
BufferedReader br = new
BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter characters, 'q' to quit.");
// read characters
do {
c = (char) br.read();
System.out.println(c);
} while(c != 'q');
}
}
You should get the String using scanner.next() and invoke String.charAt(0) method on the returned String.
Exmple :
import java.util.Scanner;
public class InputC{
public static void main(String[] args) {
// TODO Auto-generated method stub
// Declare the object and initialize with
// predefined standard input object
Scanner scanner = new Scanner(System.in);
System.out.println("Enter a character: ");
// Character input
char c = scanner.next().charAt(0);
// Print the read value
System.out.println("You have entered: "+c);
}
}
output
Enter a character:
a
You have entered: a
you just need to write this for getting value in char type.
char c = reader.next().charAt(0);
try followings.
Scanner reader = new Scanner(System.in);
char c = reader.next().charAt(0);
this will get a character from the keyboard.
import java.io.*;
class abc // enter class name (here abc is class name)
{
public static void main(String arg[])
throws IOException // can also use Exception
{
BufferedReader z =
new BufferedReader(new InputStreamReader(System.in));
char ch = (char) z.read();
} // PSVM
} // class
Try this
Scanner scanner=new Scanner(System.in);
String s=scanner.next();
char c=s.charAt(0);
Scanner key = new Scanner(System.in);
//shortcut way
char firstChar=key.next().charAt(0);
//how it works;
/*key.next() takes a String as input then,
charAt method is applied on that input (String)
with a parameter of type int (position) that you give to get
that char at that position.
You can simply read it out as:
the char at position/index 0 from the input String
(through the Scanner object key) is stored in var. firstChar (type char) */
//you can also do it in a bit elabortive manner to understand how it exactly works
String input=key.next(); // you can also write key.nextLine to take a String with spaces also
char firstChar=input.charAt(0);
char charAtAnyPos= input.charAt(pos); // in pos you enter that index from where you want to get the char from
By the way, you can't take a char directly as an input. As you can see above, a String is first taken then the charAt(0); is found and stored
Simple solution to read a charachter from user input.
Read a String. Then use charAt(0) over String
Scanner reader = new Scanner(System.in);
String str = reader.next();
char c = str.charAt(0);
That's it.
You could use typecasting:
Scanner sc= new Scanner(System.in);
char a=(char) sc.next();
This way you will take input in String due to the function 'next()' but then it will be converted into character due to the 'char' mentioned in the brackets.
This method of conversion of data type by mentioning the destination data type in brackets is called typecating. It works for me, I hope it works for u :)
Just use...
Scanner keyboard = new Scanner(System.in);
char c = keyboard.next().charAt(0);
This gets the first character of the next input.
To find the index of a character in a given sting, you can use this code:
package stringmethodindexof;
import java.util.Scanner;
import javax.swing.JOptionPane;
/**
*
* #author ASUS//VERY VERY IMPORTANT
*/
public class StringMethodIndexOf {
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
// TODO code application logic here
String email;
String any;
//char any;
//any=JOptionPane.showInputDialog(null,"Enter any character or string to find out its INDEX NUMBER").charAt(0);
//THE AVOBE LINE IS FOR CHARACTER INPUT LOL
//System.out.println("Enter any character or string to find out its INDEX NUMBER");
//Scanner r=new Scanner(System.in);
// any=r.nextChar();
email = JOptionPane.showInputDialog(null,"Enter any string or anything you want:");
any=JOptionPane.showInputDialog(null,"Enter any character or string to find out its INDEX NUMBER");
int result;
result=email.indexOf(any);
JOptionPane.showMessageDialog(null, result);
}
}
The easiest way is, first change the variable to a String and accept the input as a string. Then you can control based on the input variable with an if-else or switch statement as follows.
Scanner reader = new Scanner(System.in);
String c = reader.nextLine();
switch (c) {
case "a":
<your code here>
break;
case "b":
<your code here>
break;
default:
<your code here>
}
I have the following method:
private String doEntryScan(InputStream stream)
{
try (Scanner scanner = new Scanner(stream)) // Reading from System.in
{
String readString = scanner.nextLine();
if (readString.isEmpty())
{
readString = "\n";
}
scanner.nextLine(); //consume carriage returns if they remain
scanner.close();
return readString;
}
}
The idea is that the user can hit enter to accept defaults. Or they can enter something. If I include the line
scanner.nextLine(); //consume carriage returns if they remain
the method hangs at that point, presumably waiting for more input. If I don't have that line, I get a NoSuchElementException the next time I call this method. I'm assuming this is because there's a carriage return in the stream.
So how does one get around this? scanner.hasNext() doesn't help because it ALSO "sometimes" blocks.
By the way, in practice InputStream is System.in.
I'm trying to print a string in reverse. i.e.
hello world
should come out as:
dlrow olleh
But the outcome only shows the reverse of the first word. i.e.
olleh
Any thoughts?
import java.util.Scanner;
public class test {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner input = new Scanner(System.in);
System.out.println("Input a string:");
String s;
s = input.next();
String original, reverse = "";
original = s;
int length = original.length();
for ( int i = length - 1 ; i >= 0 ; i-- )
reverse = reverse + original.charAt(i);
System.out.println("Reverse of entered string is: "+reverse);
input.close();
}
}
Using input.next() only stores the next word in the variable (only "hello"). Try this:
System.out.println("Input a string:");
String s;
s = input.nextLine();
System.out.println("entered: " + s);
The line
s=input.next()
will only take one word.
So to get the whole line 'hello world', you've to use the nextLine() function.
s = input.nextLine();
Your scanner object returns only the next complete token through the input.next() method. A token is considered complete when there is a whitespace character. Use the nextLine() method of the scanner to get the complete input if you are using multiple words.
new StringBuilder("hello world").reverse().toString();
Maybe much more simpler.
use s.nextline() instead of s.next() as s.next() read only first token string
Scanner sc= new Scanner(System.in);
String s = sc.nextLine();
System.out.println(new StringBuilder(s).reverse().toString());
From Scanner javadoc:
public String next()
Finds and returns the next complete token from this scanner. A
complete token is preceded and followed by input that matches the
delimiter pattern. This method may block while waiting for input to
scan, even if a previous invocation of hasNext() returned true.
What happens is that the token delimiter may not be what you're expecting (newline, for instance).
If you wish your program to read the entire line input by the user, you might want to use Scanner.nextLine(), which will read the entire line input by the user, or maybe Scanner.next(String delimiter), which will allow you to enter the desired token delimiter.
Change s = input.next() to s = input.nextLine()
I can't really write some source code but maybe try using two different inputs. After that add each string to it's own variable. After that, reverse them both and add them together as an output.
I am trying to find a way to take a char input from the keyboard.
I tried using:
Scanner reader = new Scanner(System.in);
char c = reader.nextChar();
This method doesn't exist.
I tried taking c as a String. Yet, it would not always work in every case, since the other method I am calling from my method requires a char as an input. Therefore I have to find a way to explicitly take a char as an input.
Any help?
You could take the first character from Scanner.next:
char c = reader.next().charAt(0);
To consume exactly one character you could use:
char c = reader.findInLine(".").charAt(0);
To consume strictly one character you could use:
char c = reader.next(".").charAt(0);
Setup scanner:
reader.useDelimiter("");
After this reader.next() will return a single-character string.
There is no API method to get a character from the Scanner. You should get the String using scanner.next() and invoke String.charAt(0) method on the returned String.
Scanner reader = new Scanner(System.in);
char c = reader.next().charAt(0);
Just to be safe with whitespaces you could also first call trim() on the string to remove any whitespaces.
Scanner reader = new Scanner(System.in);
char c = reader.next().trim().charAt(0);
There are three ways to approach this problem:
Call next() on the Scanner, and extract the first character of the String (e.g. charAt(0)) If you want to read the rest of the line as characters, iterate over the remaining characters in the String. Other answers have this code.
Use setDelimiter("") to set the delimiter to an empty string. This will cause next() to tokenize into strings that are exactly one character long. So then you can repeatedly call next().charAt(0) to iterate the characters. You can then set the delimiter to its original value and resume scanning in the normal way!
Use the Reader API instead of the Scanner API. The Reader.read() method delivers a single character read from the input stream. For example:
Reader reader = new InputStreamReader(System.in);
int ch = reader.read();
if (ch != -1) { // check for EOF
// we have a character ...
}
When you read from the console via System.in, the input is typically buffered by the operating system, and only "released" to the application when the user types ENTER. So if you intend your application to respond to individual keyboard strokes, this is not going to work. You would need to do some OS-specific native code stuff to turn off or work around line-buffering for console at the OS level.
Reference:
How to read a single char from the console in Java (as the user types it)?
You can solve this problem, of "grabbing keyboard input one char at a time" very simply. Without having to use a Scanner all and also not clearing the input buffer as a side effect, by using this.
char c = (char)System.in.read();
If all you need is the same functionality as the C language "getChar()" function then this will work great. The Big advantage of the "System.in.read()" is the buffer is not cleared out after each char your grab. So if you still need all the users input you can still get the rest of it from the input buffer. The "char c = scanner.next().charAt(0);" way does grab the char but will clear the buffer.
// Java program to read character without using Scanner
public class Main
{
public static void main(String[] args)
{
try {
String input = "";
// Grab the First char, also wait for user input if the buffer is empty.
// Think of it as working just like getChar() does in C.
char c = (char)System.in.read();
while(c != '\n') {
//<do your magic you need to do with the char here>
input += c; // <my simple magic>
//then grab the next char
c = (char)System.in.read();
}
//print back out all the users input
System.out.println(input);
} catch (Exception e){
System.out.println(e);
}
}
}
Hope this helpful, and good luck! P.S. Sorry i know this is an older post, but i hope that my answer bring new insight and could might help other people who also have this problem.
This actually doesn't work:
char c = reader.next().charAt(0);
There are some good explanations and references in this question:
Why doesn't the Scanner class have a nextChar method?
"A Scanner breaks its input into tokens using a delimiter pattern", which is pretty open ended. For example when using this
c = lineScanner.next().charAt(0);
for this line of input
"(1 + 9) / (3 - 1) + 6 - 2"
the call to next returns "(1", c will be set to '(', and you'll end up losing the '1' on the next call to next()
Typically when you want to get a character you would like to ignore whitespace. This worked for me:
c = lineScanner.findInLine("[^\\s]").charAt(0);
Reference:
regex to match a single character that is anything but a space
The best way to take input of a character in Scanner class is:
Scanner sca=new Scanner(System.in);
System.out.println("enter a character");
char ch=sca.next().charAt(0);
You should use your custom input reader for faster results instead of extracting first character from reading String.
Link for Custom ScanReader and explanation: https://gist.github.com/nik1010/5a90fa43399c539bb817069a14c3c5a8
Code for scanning Char :
BufferedInputStream br=new BufferedInputStream(System.in);
char a= (char)br.read();
There are two approaches, you can either take exactly one character or strictly one character.
When you use exactly, the reader will take only the first character, irrespective of how many characters you input.
For example:
import java.util.Scanner;
public class ReaderExample {
public static void main(String[] args) {
try {
Scanner reader = new Scanner(System.in);
char c = reader.findInLine(".").charAt(0);
reader.close();
System.out.print(c);
} catch (Exception ex) {
System.out.println(ex.getMessage());
}
}
}
When you give a set of characters as input, say "abcd", the reader will consider only the first character i.e., the letter 'a'
But when you use strictly, the input should be just one character. If the input is more than one character, then the reader will not take the input
import java.util.Scanner;
public class ReaderExample {
public static void main(String[] args) {
try {
Scanner reader = new Scanner(System.in);
char c = reader.next(".").charAt(0);
reader.close();
System.out.print(c);
} catch (Exception ex) {
System.out.println(ex.getMessage());
}
}
}
Suppose you give input "abcd", no input is taken, and the variable c will have Null value.
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
Scanner reader = new Scanner(System.in);
char c = reader.next(".").charAt(0);
}
}
To get only one character char c = reader.next(".").charAt(0);
import java.util.Scanner;
public class userInput{
public static void main(String[] args){
// Creating your scanner with name kb as for keyBoard
Scanner kb = new Scanner(System.in);
String name;
int age;
char bloodGroup;
float height;
// Accepting Inputs from user
System.out.println("Enter Your Name");
name = kb.nextLine(); // for entire line of String including spaces
System.out.println("Enter Your Age");
age = kb.nextInt(); // for taking Int
System.out.println("Enter Your BloodGroup : A/B/O only");
bloodGroup = kb.next().charAt(0); // For character at position 0
System.out.println("Enter Your Height in Meters");
height = kb.nextFloat(); // for taking Float value
// closing your scanner object
kb.close();
// Outputting All
System.out.println("Name : " +name);
System.out.println("Age : " +age);
System.out.println("BloodGroup : " +bloodGroup);
System.out.println("Height : " +height+" m");
}
}
Try this:
char c=S.nextLine().charAt(0);
// Use a BufferedReader to read characters from the console.
import java.io.*;
class BRRead {
public static void main(String args[]) throws IOException
{
char c;
BufferedReader br = new
BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter characters, 'q' to quit.");
// read characters
do {
c = (char) br.read();
System.out.println(c);
} while(c != 'q');
}
}
You should get the String using scanner.next() and invoke String.charAt(0) method on the returned String.
Exmple :
import java.util.Scanner;
public class InputC{
public static void main(String[] args) {
// TODO Auto-generated method stub
// Declare the object and initialize with
// predefined standard input object
Scanner scanner = new Scanner(System.in);
System.out.println("Enter a character: ");
// Character input
char c = scanner.next().charAt(0);
// Print the read value
System.out.println("You have entered: "+c);
}
}
output
Enter a character:
a
You have entered: a
you just need to write this for getting value in char type.
char c = reader.next().charAt(0);
try followings.
Scanner reader = new Scanner(System.in);
char c = reader.next().charAt(0);
this will get a character from the keyboard.
import java.io.*;
class abc // enter class name (here abc is class name)
{
public static void main(String arg[])
throws IOException // can also use Exception
{
BufferedReader z =
new BufferedReader(new InputStreamReader(System.in));
char ch = (char) z.read();
} // PSVM
} // class
Try this
Scanner scanner=new Scanner(System.in);
String s=scanner.next();
char c=s.charAt(0);
Scanner key = new Scanner(System.in);
//shortcut way
char firstChar=key.next().charAt(0);
//how it works;
/*key.next() takes a String as input then,
charAt method is applied on that input (String)
with a parameter of type int (position) that you give to get
that char at that position.
You can simply read it out as:
the char at position/index 0 from the input String
(through the Scanner object key) is stored in var. firstChar (type char) */
//you can also do it in a bit elabortive manner to understand how it exactly works
String input=key.next(); // you can also write key.nextLine to take a String with spaces also
char firstChar=input.charAt(0);
char charAtAnyPos= input.charAt(pos); // in pos you enter that index from where you want to get the char from
By the way, you can't take a char directly as an input. As you can see above, a String is first taken then the charAt(0); is found and stored
Simple solution to read a charachter from user input.
Read a String. Then use charAt(0) over String
Scanner reader = new Scanner(System.in);
String str = reader.next();
char c = str.charAt(0);
That's it.
You could use typecasting:
Scanner sc= new Scanner(System.in);
char a=(char) sc.next();
This way you will take input in String due to the function 'next()' but then it will be converted into character due to the 'char' mentioned in the brackets.
This method of conversion of data type by mentioning the destination data type in brackets is called typecating. It works for me, I hope it works for u :)
Just use...
Scanner keyboard = new Scanner(System.in);
char c = keyboard.next().charAt(0);
This gets the first character of the next input.
To find the index of a character in a given sting, you can use this code:
package stringmethodindexof;
import java.util.Scanner;
import javax.swing.JOptionPane;
/**
*
* #author ASUS//VERY VERY IMPORTANT
*/
public class StringMethodIndexOf {
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
// TODO code application logic here
String email;
String any;
//char any;
//any=JOptionPane.showInputDialog(null,"Enter any character or string to find out its INDEX NUMBER").charAt(0);
//THE AVOBE LINE IS FOR CHARACTER INPUT LOL
//System.out.println("Enter any character or string to find out its INDEX NUMBER");
//Scanner r=new Scanner(System.in);
// any=r.nextChar();
email = JOptionPane.showInputDialog(null,"Enter any string or anything you want:");
any=JOptionPane.showInputDialog(null,"Enter any character or string to find out its INDEX NUMBER");
int result;
result=email.indexOf(any);
JOptionPane.showMessageDialog(null, result);
}
}
The easiest way is, first change the variable to a String and accept the input as a string. Then you can control based on the input variable with an if-else or switch statement as follows.
Scanner reader = new Scanner(System.in);
String c = reader.nextLine();
switch (c) {
case "a":
<your code here>
break;
case "b":
<your code here>
break;
default:
<your code here>
}