In Java, there are three ways to read input from a console :
- System.console (JDK 1.6)
- Scanner (JDK 1.5)
- BufferedReader + InputStreamReader (Classic)
1. System.console
Since JDK 1.6, the developer starts to switch to the more simple and powerful java.io.Console class.
JavaConsole.java
package com.mkyong.io;
import java.io.Console;
public class JavaConsole {
public static void main(String[] args) {
Console console = System.console();
String input = "";
while (!"q".equalsIgnoreCase(input)) {
System.out.print("Enter something (q to quite): ");
input = console.readLine();
System.out.println("input : " + input);
}
System.out.println("bye bye!");
}
}
The System.console() will return null in IDE, running the class in console or terminal manually.
~/projects/target/classes$ java com.mkyong.io.JavaConsole
Enter something (q to quite): hello 123
input : hello 123
Enter something (q to quite): hello Java
input : hello Java
Enter something (q to quite): mkyong
input : mkyong
Enter something (q to quite): q
input : q
bye bye!
P.S More Java System.console() examples.
2. Scanner
Before JDK 1.6, this is the Scanner way to read input from the console.
JavaScanner.java
package com.mkyong.io;
import java.util.Scanner;
public class JavaScanner {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
String input = "";
while (!"q".equalsIgnoreCase(input)) {
System.out.print("Enter something (q to quite): ");
input = scanner.nextLine();
System.out.println("input : " + input);
}
System.out.println("bye bye!");
}
}
Enter something (q to quite): hello mkyong
input : hello mkyong
Enter something (q to quite): jdk 1.5
input : jdk 1.5
Enter something (q to quite): exit
input : exit
Enter something (q to quite): q
input : q
bye bye!
P.S More Java Scanner examples examples.
3. BufferedReader + InputStreamReader
In the old days, JDK 1.1, we use BufferedReader + InputStreamReader to read input from the console.
JavaBufferedReaderClassic.java
package com.mkyong.io;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class JavaBufferedReaderClassic {
public static void main(String[] args) {
BufferedReader br = null;
try {
br = new BufferedReader(new InputStreamReader(System.in));
String input = "";
while (!"q".equalsIgnoreCase(input)) {
System.out.print("Enter something (q to quite): ");
input = br.readLine();
System.out.println("input : " + input);
}
System.out.println("bye bye!");
} catch (IOException e) {
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
JDK 1.7 try-with-resources
JavaBufferedReader.java
package com.mkyong.io;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class JavaBufferedReader {
public static void main(String[] args) {
// jdk 1.7
try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
String input = "";
while (!"q".equalsIgnoreCase(input)) {
System.out.print("Enter something (q to quite): ");
input = br.readLine();
System.out.println("input : " + input);
}
System.out.println("bye bye!");
} catch (IOException e) {
e.printStackTrace();
}
}
}
Sir, Can u please update this blog with the latest functionality if it is available in newer versions of java?
This article is too old so m concerned if I’m not learning updated and latest way to solve the issue.
System.console() also does not work in competitive programming environments, such as open.Kattis.com
hello why we use exception in BufferReader
Hello MKYong & everyone, I was learning java2 jdk1.3 in 2002-2003 then suddenly I had to left it bcz of change of field now again after an interval of 12-13years I m again interested in learning Java, so I found your article helpful as you have given all three examples of jdk1.3,1.5&1.6 that’s very good I appreciate your work, thanks regards from me(Mohsin)
very helpful Thank you…!
There is another method for reading console
DataInputStream dis= new DataInputStream(System.in); which defined in java.io. Like BufferedReader it also uses Integr.parseInt(dis.readLine( )); to read from console
Thanks for you input. For JDK >= 1.6, better use the Console class.
which is the best method to read input from the above mentioned methods?
and please tell me use of each method?
because i’m confused.
Article is updated, for JDK >= 1.6, better use the java.io.Console class.
Check out this link Java program to get input from user
Is it possible to getting console error in String..pls guide me or mail me…Advanced Thanks.
This was very helpful for my facial reconstruction simulation project…
thank you..!!
Really nice tutorial…
the buffered reader worked better than System.in thanks
You are so helpful. May God bless you.
Can you give me a hand in using JDPAPI to protect some credentials like, password, username network address.
reader worked well much better than System.in
and worked…. thanks
Is it legal not to call close method of BufferedReader class while reading from console?
Same question….
Since java 6 there is another shorter way (like in c#) to read/write from the system console :
System.console().readLine();
or just instatiate a Console reference (java.io.Console) and assign a it to the system’s console :
Console c = System.console();
c.readLine();
Also the Console way is thread safe the other two methods are not just to point out another difference. If you look in the source code of the java.io.Console class you will see that readLine uses locks to prevent concurrent read/write access.
Personally i prefer the console way for simple and the scanner way, when you need to tokenize the input.
Thanks, article is updated, the JDK 1.6 System.console() is a better choice.
Scanner IMHO is great, since it seems to me more concise, however if you enter dot’s and/or comma’s through numeric pad section of your keyboard, – be surprised to find out that you are not a citizen of Great Britain: Scanner mixes up numeric locales (I am from Russia just in case)
Thanks for your input.
Wow you are amazing, each day i randomly search in google and i find solutions in this page.
thank you again!
great …… useful to me
I want to read spaces from input and the scanner throws an exception while doing so. I want to use every ‘other’ whitespace character as delimiter except space. Any help with scanner? Or shall I continue to use BufferedReader?
I have very small inputs to fetch as in “Hello World” or “I am new”
Useful for me, thanks!
But scanner will not be a good practice unless the input is very small. ( less than 50KB of data is to be read )
also can you provide which will be more efficient
This example is not a useful solution for me.
I want to accept current/default number (by pressing enter) or change number by
input number and press enter.
Further if I happen to input a character java crashes, very bad !
I haven’t found a solution yet,
/Jarl
Can you provide steps to simulate how you crashed the Java console?
What about the System.Io.Console class new to Java 6? It seems even simpler, but I heard it can produce glitches depending on whether console on the particular JVM is started automatically or not.
I mean…java.io.console…
I prefer Scanner personally. Great tutorial, thanks!
ya , Scanner provide many new functionality, may be i’m an old guy, used to BufferedReader already haha
Excellent!! Very helpfull.