Console readLine() method in Java with Examples

12 Jun, 2020
The readLine() method of Console class in Java is of two types:
1. The readLine() method of Console class in Java is used to read a single line of text from the console.
Syntax:
public String readLine()

Parameters: This method does not accept any parameter.
Return value: This method returns the string containing the line that is read from the console. It returns null if the stream has ended.
Exceptions: This method throws IOError if an I/O error occurs.
Note: System.console() returns null in an online IDE.
Below programs illustrate readLine() method in Console class in IO package:
Program 1:
// Java program to illustrate// Console readLine() method  import java.io.*;  public class GFG {    public static void main(String[] args)    {        // Create the console object        Console cnsl            = System.console();          if (cnsl == null) {            System.out.println(                "No console available");            return;        }          // Read line        String str = cnsl.readLine(            "Enter string : ");          // Print        System.out.println(            "You entered : " + str);    }}
Program 2:
// Java program to illustrate// Console readLine() method  import java.io.*;  public class GFG {    public static void main(String[] args)    {        // Create the console object        Console cnsl            = System.console();          if (cnsl == null) {            System.out.println(                "No console available");            return;        }          // Read line        String str = cnsl.readLine(            "Enter string : ");          // Print        System.out.println(            "You entered : " + str);    }}
2. The readLine(String, Object) method of Console class in Java is used to read a single line of text from the console by providing a formatted prompt.
Syntax:
public String readLine(String fmt,
                      Object... args)

Parameters: This method accepts two parameters:
fmt – It represents the format of the string.
args – It represents the arguments that are referenced by the format specifiers in the string format.
Return value: This method returns the string that contains the line read from the console. It returns null if the stream is ended.
Exceptions:
IllegalFormatException – This method throws IllegalFormatException if string format contains an illegal syntax or a format specifier is not compatible with the given arguments or insufficient arguments given the format string or other conditions that are illegal.
IOError – This method throws IOError if an I/O error occurs.
Below programs illustrate readLine(String, Object) method in Console class in IO package:
Program 1:
// Java program to illustrate// Console readLine(String, Object) method  import java.io.*;  public class GFG {    public static void main(String[] args)    {        // Create the console object        Console cnsl            = System.console();          if (cnsl == null) {            System.out.println(                "No console available");            return;        }          String fmt = "%1$4s %2$10s %3$10s%n";          // Read line        String str            = cnsl.readLine(                fmt, "Enter", "string : ");          // Print line        System.out.println(            "You entered : " + str);    }}
Program 2:
// Java program to illustrate// Console readLine(String, Object) method  import java.io.*;  public class GFG {    public static void main(String[] args)    {        // Create the console object        Console cnsl            = System.console();          if (cnsl == null) {            System.out.println(                "No console available");            return;        }          String fmt = "%1$4s %2$10s %3$10s%n";          // Read line        String str            = cnsl.readLine(                fmt, "Enter", "string : ");          // Print line        System.out.println(            "You entered : " + str);    }}
References:1. https://docs.oracle.com/javase/10/docs/api/java/io/Console.html#readLine()2. https://docs.oracle.com/javase/10/docs/api/java/io/Console.html#readLine(java.lang.String, java.lang.Object...)
Java-Functions
Java-IO package
Java
Java
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