my java console is not working

Question

i have a very serious problem with working with my java console. i have already enabled "show console" in java program which is located at start>control panel>programs>java. i double clicked it to open, went to advanced and enabled show console. BUT when i try to run this program, I'm getting the error message no console!. please help!! thanks in advance.

    public class RegexTest {

    public static void main(String[] args) {
        // TODO code application logic here
        Console console=System.console();

        if(console==null){
            System.err.println("no console");
            System.exit(1);
        }
        while(true){
            Pattern pattern=Pattern.compile(console.readLine("enter your regex: "));
            Matcher matcher=pattern.matcher(console.readLine("enter inputstring to serch"));
            boolean found=false;
            while(matcher.find()){
                console.format("i found the text"+" %s starting at index %d and ending at  index %d.%n",matcher.group(),matcher.start(),matcher.end());
                found=true;
            }
            if(!found){
                console.format("no match found %n");
            }
        }
    }
}

here is the output.

no console
Java Result: 1
BUILD SUCCESSFUL (total time: 13 seconds)

Answer 1

To avoid creating new OS console window when running code most IDEs like Eclipse, NetBeans, InteliiJ is using javaw.exe (window-less) instead of java.exe.

Since javaw.exe doesn't create console window there is no console on which you would want to print so System.console() returns null.

This example may be easier to understand what I mean.

import java.awt.FlowLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;

public class Demo {

    public static void main(String[] args) throws Exception {

        JFrame frame = new JFrame("Hello");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLayout(new FlowLayout());
        frame.setSize(250, 100);

        frame.add(new JLabel("HELLO WORLD"));
        frame.add(new JLabel("Is console available? " + (System.console() != null)));
        frame.setVisible(true);

        System.out.println("text in console");
    }

}

If you run this code using java -cp pathToYourPackage Demo you will see two windows:

But if you use javaw -cp pathToYourPackage Demo you will not see console window (that is why most IDEs use it) but only