JCurses Crash Course

JCurses lets a Java program take over a terminal window and draw on it like a canvas. Instead of printing lines that scroll away, you put text at exact spots, in color, and react to single key presses without waiting for Enter.

A terminal is a grid of character cells, usually 80 columns wide and 24 rows tall. Every position you give JCurses is a (column, row) pair on that grid, starting at (0, 0) in the top-left corner.

Add it to your Eclipse project

1. Download JCurses and unzip it.
2. Make a lib folder in your project and copy in two files: jcurses.jar and the native library (.dll on Windows, .so on Linux).
3. Right-click jcurses.jar → Build Path → Add to Build Path. Only the jar, not the native file.

Every drawing-mode program follows the same rhythm: clear the screen, print text somewhere, wait for a key, and shut down cleanly. A CharColor is a pair of colors: background first, then text.

import jcurses.system.*;

public class Hello {
  public static void main(String[] args) {
    CharColor plain = new CharColor(CharColor.BLACK, CharColor.WHITE);
    CharColor green = new CharColor(CharColor.BLACK, CharColor.GREEN);
    CharColor red   = new CharColor(CharColor.BLACK, CharColor.RED);

    Toolkit.clearScreen(plain);
    // printString(text, column, row, color)
    Toolkit.printString("Hello from JCurses!", 5, 2, green);
    Toolkit.printString("Press any key (q to quit)", 5, 4, plain);

    InputChar key = Toolkit.readCharacter(); // waits for ONE key
    Toolkit.printString("You pressed: " + key.getCharacter(), 5, 6, red);
    Toolkit.readCharacter();

    Toolkit.shutdown(); // always last: restores the terminal
  }
}

• printString("Hi", 5, 2, …) starts 5 columns in and 2 rows down.
• Skip Toolkit.shutdown() and your terminal can be left in a weird state after the program ends.

Eclipse's Console panel is not a real terminal, so the green Run button won't work for JCurses. Instead, save in Eclipse (it compiles into the bin folder), open Command Prompt or a terminal in your project folder, and run:

# Windows: entries separated by a semicolon
java -cp bin;lib\jcurses.jar Hello

# Linux / macOS: entries separated by a colon
java -cp bin:lib/jcurses.jar Hello

• -cp is the classpath: where Java looks for your classes and the jar.
• Eclipse's own Terminal view (Window → Show View → Other → Terminal) is a real terminal, so it works too.

Widget mode works like a tiny version of Swing. Make a Window, attach a layout manager to its root panel, add widgets, then call show().

Window w = new Window(40, 10, true, "My First Window");
DefaultLayoutManager layout = new DefaultLayoutManager();
layout.bindToContainer(w.getRootPanel());

Label msg = new Label("Hello! Press Enter on the button.");
Button b = new Button("Close");
b.addListener(e -> w.close());   // runs when Enter is pressed on it

// addWidget(widget, x, y, width, height, hAlign, vAlign)
layout.addWidget(msg, 0, 1, 38, 1, WidgetsConstants.ALIGNMENT_CENTER,
                                   WidgetsConstants.ALIGNMENT_CENTER);
layout.addWidget(b,   0, 4, 38, 3, WidgetsConstants.ALIGNMENT_CENTER,
                                   WidgetsConstants.ALIGNMENT_CENTER);
w.show();

Other widgets to try