Basic shell control created using JavaFX. Can be embedded into Swing and JavaFX applications. Emulates a command line UI. To process commands, use the `onEnter` functional interface.

ShellControl.java

import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.event.EventHandler;
import javafx.scene.control.TextArea;
import javafx.scene.input.KeyEvent;

import java.util.ArrayList;
import java.util.function.Consumer;

public class ShellControl extends TextArea {
    private String prompt = ">>>";
    private String input;
    private int caretPos, histIndex = 0;
    public Consumer<ShellControl> onEnter;
    private ArrayList<String> history;

    public String getPrompt() {
        return this.prompt + " ";
    }

    public void setPrompt(String prompt) {
        this.setText(this.getText().replace(this.prompt, prompt));
        this.prompt = prompt;
    }

    public String getInput() {
        return this.input;
    }

    private void setInput(String input) {
        this.input = input;
    }

    public void print(String text) {
        this.appendText("\n" + text);
    }

    public void println(String text) {
        this.appendText(String.format("\n%s\n", text));
    }

    public void println() {
        this.appendText("\n");
    }

    public void printf(String format, Object... args) {
        this.appendText(String.format("\n" + format, args));
    }

    private int getLongLastPos() {
        return this.getText().lastIndexOf(this.getPrompt()) + this.getPrompt().length();
    }

    public ArrayList<String> getHistory() {
        return this.history;
    }

    public ShellControl() {
        history = new ArrayList<>();
        this.setText(this.getPrompt());
        this.textProperty().addListener(new ChangeListener<String>() {
            @Override
            public void changed(ObservableValue<? extends String> observable, String oldValue, String newValue) {
                caretPos = getCaretPosition();
                int pos = oldValue.lastIndexOf(getPrompt()) + getPrompt().length() + 1;
                if (caretPos < pos && oldValue.length() > newValue.length()) {
                    setText(oldValue);
                    positionCaret(caretPos);
                }
            }
        });
        this.addEventFilter(KeyEvent.KEY_PRESSED, new EventHandler<KeyEvent>() {
            @Override
            public void handle(KeyEvent event) {
                switch (event.getCode()) {
                    case ENTER:
                        event.consume();
                        setInput(getText().substring(getLongLastPos()));
                        if (getInput().equals("cls") | getInput().equals("clear"))
                            clear();
                        else
                            onEnter.accept(ShellControl.this);
                        appendText(getPrompt());
                        caretPos = getCaretPosition();
                        history.add(getInput());
                        histIndex++;
                        break;
                    case UP:
                        event.consume();
                        if (!history.isEmpty() & histIndex > 0)
                            replaceText(getLongLastPos(), getText().length(), history.get(--histIndex));
                        break;
                    case DOWN:
                        event.consume();
                        if (!history.isEmpty() & histIndex < history.size())
                            replaceText(getLongLastPos(), getText().length(), history.get(++histIndex));
                        break;
                    case RIGHT:
                        if (!history.isEmpty() && getText().substring(getLongLastPos()).isEmpty()) {
                            event.consume();
                            replaceText(getLongLastPos(), getText().length(), history.get(history.size() - 1));
                        }
                        break;
                }
            }
        });
        this.positionCaret(getLongLastPos());
    }
}

ShellControlTest.java

package shellcontrol;

import javafx.application.Platform;
import javafx.embed.swing.JFXPanel;
import javafx.scene.Scene;
import javafx.scene.text.Font;

import javax.swing.*;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class ShellTest {

    public static void main(String[] args) {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JFXPanel panel = new JFXPanel();
        frame.add(panel);
        Platform.runLater(() -> {
            ShellControl control = new ShellControl();
            /*control.setStyle("-fx-control-inner-background: black; -fx-text-fill: white");
            control.setFont(new Font("Consolas", control.getFont().getSize() + 3));
            control.setPrompt("4ZVla =>> ");*/

            control.requestFocus();
            /*control.onEnter = (ShellControl c) -> {
                try {
                    //c.printf("%s\n", c.getInput());
                    ProcessBuilder builder = new ProcessBuilder("cmd.exe", "/c", c.getInput());
                    builder.redirectErrorStream(true);
                    Process process = builder.start();
                    new BufferedReader(new InputStreamReader(process.getInputStream())).lines().forEach(c::print);
                    c.println();
                } catch (IOException e) {
                    c.printf("ERROR: %s\n", e.toString());
                }
            };*/
            control.onEnter = c -> c.println(c.getInput());
            Scene scene = new Scene(control);
            panel.setScene(scene);
        });

        frame.setSize(500, 500);
        frame.setVisible(true);
    }
}