Reading a single char in Java

Question

How can a char be entered in Java from keyboard?

Answer 1

You can either scan an entire line:

Scanner s = new Scanner(System.in);
String str = s.nextLine();

Or you can read a single char, given you know what encoding you're dealing with:

char c = (char) System.in.read();

Answer 2

You can use Scanner like so:

Scanner s= new Scanner(System.in);
char x = s.next().charAt(0);

By using the charAt function you are able to get the value of the first char without using external casting.

Answer 3

Using nextline and System.in.read as often proposed requires the user to hit enter after typing a character. However, people searching for an answer to this question, may also be interested in directly respond to a key press in a console!

I found a solution to do so using jline3, wherein we first change the terminal into rawmode to directly respond to keys, and then wait for the next entered character:

var terminal = TerminalBuilder.terminal()
terminal.enterRawMode()
var reader = terminal.reader()

var c = reader.read()

<dependency>
    <groupId>org.jline</groupId>
    <artifactId>jline</artifactId>
    <version>3.12.3</version>
</dependency>

Answer 4

You can use a Scanner for this. It's not clear what your exact requirements are, but here's an example that should be illustrative:

    Scanner sc = new Scanner(System.in).useDelimiter("\\s*");
    while (!sc.hasNext("z")) {
        char ch = sc.next().charAt(0);
        System.out.print("[" + ch + "] ");
    }

If you give this input:

123 a b c x   y   z

The output is:

[1] [2] [3] [a] [b] [c] [x] [y] 

So what happens here is that the Scanner uses \s* as delimiter, which is the regex for "zero or more whitespace characters". This skips spaces etc in the input, so you only get non-whitespace characters, one at a time.

Answer 5

i found this way worked nice:

    {
    char [] a;
    String temp;
    Scanner keyboard = new Scanner(System.in);
    System.out.println("please give the first integer :");
    temp=keyboard.next();
    a=temp.toCharArray();
    }

you can also get individual one with String.charAt()

Answer 6

Here is a class 'getJ' with a static function 'chr()'. This function reads one char.

import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.io.IOException;

class getJ {
    static char  chr()throws IOException{  
        BufferedReader bufferReader =new BufferedReader(new InputStreamReader(System.in));
        return bufferReader.readLine().charAt(0);
    }
}

In order to read a char use this:

anyFunc()throws IOException{
...
...
char c=getJ.chr();
}

Because of 'chr()' is static, you don't have to create 'getJ' by 'new' ; I mean you don't need to do:

getJ ob = new getJ;
c=ob.chr();

You should remember to add 'throws IOException' to the function's head. If it's impossible, use try / catch as follows:

anyFunc(){// if it's impossible to add 'throws IOException' here
...
try
{
char c=getJ.chr(); //reads a char into c
} 
catch(IOException e)
{
System.out.println("IOException has been caught");
}

Credit to: tutorialspoint.com

See also: geeksforgeeks.

java bufferedreader input getchar char

Answer 7

.... char ch; ... ch=scan.next().charAt(0); . . It's the easy way to get character.

Answer 8

Maybe you could try this code:

import java.io.*;
public class Test
{
public static void main(String[] args)
{
try
  {
  BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
  String userInput = in.readLine();
  System.out.println("\n\nUser entered -> " + userInput);
  }
  catch(IOException e)
  {
  System.out.println("IOException has been caught");
  }
 }
}