Java Console readline() Method

The readline() Method of Console class is used to read a single line of text from the console.

Syntax

Parameters

Return value:

This method returns the string containing the line read from the console.

Exception:

IOException: This exception will throw if an I/O error occurs.

Example 1

import java.io.*; 
class ReadLineDemo { 
public static void main(String args[]) 
throws IOException 
{ 
  // create a BufferedReader using System.in 
  BufferedReader obj = new BufferedReader(new InputStreamReader(System.in)); 
   String str; 

 System.out.println("Enter lines of text."); 
 System.out.println("Enter 'stop' to quit."); 
   do { 

    str = obj.readLine(); 
    System.err.println(str); 
  }   while(!str.equals("stop")); 
} 
}

Output:

Enter lines of text.
Enter 'stop' to quit.

Example 2

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;

public class DemoBuffer
{

	public static void main(String[] args) {	
		
		try {
			
			Reader reader = new FileReader("E:\\users\\flushUsing.txt");

			try(BufferedReader bufferedReader =
			    new BufferedReader(reader)){

			    String line = bufferedReader.readLine();
			    while(line != null) {
			        //do something with line

			        line = bufferedReader.readLine();
			        System.out.println(line);
			    }

			}
		} catch (IOException e) {
			
			System.out.println(e);
		}		
		
	}
}

Output:

File Read:
The main difference between BufferedReader and BufferedInputStream is that BufferedReader reads characters (text), whereas the BufferedInputStream reads raw bytes.
Null

Java Console readLine(String fmt, Object args) Method

The readLine(String fmt, Object args) method is a static method of Java Console class. It is used to provide a formatted prompt, then reads a single line of text from the console.

Syntax

Parameters

fmt: A format string as described in Format string syntax.

args: Arguments referenced by the format specifiers in the format string, the extra arguments are ignored.

Return value:

This method returns the string which contains the line read from the console. It does not include any line-termination characters. If an end of the stream has been reached, this method will return null.

Exception:

IllegalFormatException: If given the format string is incompatible and insufficient arguments.

IOError: If an I/O error occurs.

Example 1

import java.io.Console; 
class Main
{ 
    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); 
   } 
}

Output:

Enter your name: Jony
Here is your name: Jony

Example 2

import java.io.Console;
public class Readl {
   public static void main(String[] args) {      
	  
       Console col = System.console(); 
      String fmt = "%1$4s";
      String alpha = null;
      if(col==null) {
    	  System.out.println("No console Available");
      }
      
      try {
         // creates a console object
       col= System.console();

         
          // read the line from the user input
            alpha = col.readLine(fmt, "Enter :","Alphabets: ");
            
            // prints
            col.format(fmt, "Alphabets entered: " + alpha);  
         } catch(Exception e) {
         System.out.println(e);
      }
   }
}

Output:

Enter : javatpoint
Alphabets entered: javatpoint

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