Question

I wanted to know if there was a way to take a String – let’s say:

String str = "blabla";

and do:

System.in.setText(str);   

I know this does not work – I wanted to know if there was a way to do this. And then send that same string. Just like if you would write in the console and press Enter.

It is a program with a server socket and I am trying to send a String over a port, so that the other application would know what to do with it.

EDIT :
I found a way to redirect the inputstream to a Textfield when the user writes in the Textfield it sends it over the System.in.

import java.io.*;
import javax.swing.*;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;

public class TextfieldInputStream extends InputStream implements DocumentListener {

    private JTextField tf;
    private String str = null;
    private int pos = 0;

    public TextfieldInputStream(JTextField jtf) {
        tf = jtf;
    }

    @Override
    public int read() {
        //test if the available input has reached its end
        //and the EOS should be returned 
        if(str != null && pos == str.length()){
            str = null;
            //this is supposed to return -1 on "end of stream"
            //but I'm having a hard time locating the constant
            return java.io.StreamTokenizer.TT_EOF;
        }
        //no input available, block until more is available because that's
        //the behavior specified in the Javadocs
        while (str == null || pos >= str.length()) {
            try {
                //according to the docs read() should block until new input is available
                synchronized (this) {
                    this.wait();
                }
            } catch (InterruptedException ex) {
                ex.printStackTrace();
            }
        }
        //read an additional character, return it and increment the index
        return str.charAt(pos++);
    }

    public void changedUpdate(DocumentEvent e) {
        // TODO Auto-generated method stub
    }

    public void insertUpdate(DocumentEvent e){
        str = tf.getText() + "\n";
        pos = 0;
        synchronized (this) {
            //maybe this should only notify() as multiple threads may
            //be waiting for input and they would now race for input
            this.notifyAll();
        }
    }

    public void removeUpdate(DocumentEvent e){
        // TODO Auto-generated method stub
    }
}

Answer 1

package test.t100.t007;

import java.io.ByteArrayInputStream;
import java.util.Scanner;

public class SystemIn {

    public static void main(String[] args) {
        String str = "blabla";
        ByteArrayInputStream bais = new ByteArrayInputStream(str.getBytes());
        System.setIn(bais);
        // We might use the ByteArrayInputStream here, but going with System.in..
        Scanner scanner = new Scanner(System.in);
        String input = scanner.next();
        System.out.println(input);
    }
}