Java.io.Console class in Java

• It is used to read from and write to the console, if one exists.
• Console is primarily a convenience class because most of its functionality is available through System.in and System.out. However, its use can simplify some types of console interactions, especially when reading strings from the console.
• Console supplies no constructors. Instead, a Console object is obtained by calling System.console( ), which is shown here:

  static  Console console( )

  If a console is available, then a reference to it is returned. Otherwise, null is returned. A console will not be available in all cases. Thus, if null is returned, no console I/O is possible.
• It provides methods to read text and password. If you read password using Console class, it will not be displayed to the user.The java.io.Console class is attached with system console internally.

• writer : Retrieves the unique PrintWriter object associated with this console. Syntax:

  public PrintWriter writer() 
  Returns: The printwriter associated with this console

• reader : Retrieves the unique Reader object associated with this console. Syntax:

  public Reader reader()  
  Returns: The reader associated with this console
  

• format : Writes a formatted string to this console's output stream using the specified format string and arguments. Syntax:

  public Console format(String fmt, Object... args)
  Parameters:
  fmt - A format string as described in Format string syntax
  args - Arguments referenced by the format specifiers in the format string. 
  If there are more arguments than format specifiers, the extra arguments are ignored.
  Returns:This console
  Throws: IllegalFormatException 
  

• printf : A convenience method to write a formatted string to this console's output stream using the specified format string and arguments. Syntax:

  public Console printf(String format, Object... args)
  Parameters:
  format - A format string as described in Format string syntax.
  args - Arguments referenced by the format specifiers in the format string. 
  If there are more arguments than format specifiers, the extra arguments are ignored.
  Returns:This console
  Throws:IllegalFormatException 
  

• readLine : Provides a formatted prompt, then reads a single line of text from the console. Syntax:

  public String readLine(String fmt,Object... args) 
  Parameters:
  fmt - A format string as described in Format string syntax.
  args - Arguments referenced by the format specifiers in the format string. 
  If there are more arguments than format specifiers, the extra arguments are ignored.
  Returns: A string containing the line read from the console, 
  not including any line-termination characters, or null 
  if an end of stream has been reached.
  Throws:
  IllegalFormatException
  IOError - If an I/O error occurs.
  

• readLine : Reads a single line of text from the console. Syntax:

  public String readLine() 
  Returns: A string containing the line read from the console,
   not including any line-termination characters, or null 
  if an end of stream has been reached.
  Throws: IOError 
  

• readPassword: Provides a formatted prompt, then reads a password or passphrase from the console with echoing disabled. Syntax:

  public char[] readPassword(String fmt,Object... args)
  Parameters:
  fmt - A format string as described in Format string syntax for the prompt text.
  args - Arguments referenced by the format specifiers in the format string.
  Returns: A character array containing the password or passphrase read 
  from the console, not including any line-termination characters, or null 
  if an end of stream has been reached.
  Throws:
  IllegalFormatException 
  IOError

• readPassword : Reads a password or passphrase from the console with echoing disabled Syntax:

  public char[] readPassword()
  Returns: A character array containing the password or passphrase 
  read from the console, not including any line-termination characters, or null 
  if an end of stream has been reached.
  Throws:IOError

• flush : Flushes the console and forces any buffered output to be written immediately . Syntax:

  public void flush()
  Specified by: flush in interface Flushable

// Java Program to demonstrate Console Methods

import java.io.*;
class ConsoleDemo 
{
    public static void main(String args[]) 
    {
        String str;
        
        //Obtaining a reference to the console.
        Console con = System.console();
        
        // Checking If there is no console available, then exit.
        if(con == null) 
        {
            System.out.print("No console available");
            return;
        }
        
        // Read a string and then display it.
        str = con.readLine("Enter your name: ");
        con.printf("Here is your name: %s\n", str);

        //to read password and then display it
        System.out.println("Enter the password: ");
        char[] ch=con.readPassword();

        //converting char array into string
        String pass = String.valueOf(ch);
        System.out.println("Password is: " + pass);
    }
}

Enter your name: Nishant Sharma
Here is your name: Nishant Sharma
Enter the password: 
Password is: dada