Enables colors in the Windows terminal for Java console programs. Read the comment before blindly copy pasting!

Main.java

import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.net.URL;
import java.net.URLClassLoader;

public class Main {
    static void enableColor() {
        // https://stackoverflow.com/questions/52767585/how-can-you-use-vt100-escape-codes-in-java-on-windows
        try {
            // Load classes
            URLClassLoader loader = new URLClassLoader(new URL[] {
                    new URL("https://repo1.maven.org/maven2/net/java/dev/jna/jna/5.11.0/jna-5.11.0.jar"),
                    new URL("https://repo1.maven.org/maven2/net/java/dev/jna/jna-platform/5.11.0/jna-platform-5.11.0.jar")});
            Class<?> Function = loader.loadClass("com.sun.jna.Function");
            Class<?> WinDef = loader.loadClass("com.sun.jna.platform.win32.WinDef");
            Class<?> WinNT = loader.loadClass("com.sun.jna.platform.win32.WinNT");
            Class<?> HANDLE = null;
            Class<?> DWORD = null;
            Class<?> BOOL = null;
            Class<?> DWORDByReference = null;
            for (Class<?> c : WinDef.getClasses()) {
                if (c.getSimpleName().equals("BOOL")) BOOL = c;
                else if (c.getSimpleName().equals("DWORD")) DWORD = c;
                else if (c.getSimpleName().equals("DWORDByReference")) DWORDByReference = c;
            }
            for (Class<?> c : WinNT.getClasses()) {
                if (c.getSimpleName().equals("HANDLE")) HANDLE = c;
            }

            Object GetStdHandleFunc = Function.getDeclaredMethod("getFunction", String.class, String.class).invoke(null, "kernel32", "GetStdHandle");
            Object STD_OUTPUT_HANDLE = DWORD.getConstructor(long.class).newInstance(-11);
            Object hOut = Function.getMethod("invoke", Class.class, Object[].class).invoke(GetStdHandleFunc, HANDLE, new Object[] {STD_OUTPUT_HANDLE});

            Object p_dwMode = DWORDByReference.getConstructor(DWORD).newInstance(DWORD.getConstructor(long.class).newInstance(0));
            Object GetConsoleModeFunc = Function.getDeclaredMethod("getFunction", String.class, String.class).invoke(null, "kernel32", "GetConsoleMode");
            Function.getMethod("invoke", Class.class, Object[].class).invoke(GetConsoleModeFunc, BOOL, new Object[] {hOut, p_dwMode});

            int ENABLE_VIRTUAL_TERMINAL_PROCESSING = 4;
            Object dwMode = DWORDByReference.getMethod("getValue").invoke(p_dwMode);
            DWORD.getMethod("setValue", long.class).invoke(dwMode, (int) DWORD.getMethod("intValue").invoke(dwMode) | ENABLE_VIRTUAL_TERMINAL_PROCESSING);
            Object SetConsoleModeFunc = Function.getDeclaredMethod("getFunction", String.class, String.class).invoke(null, "kernel32", "SetConsoleMode");
            Function.getMethod("invoke", Class.class, Object[].class).invoke(SetConsoleModeFunc, BOOL, new Object[] {hOut, dwMode});

            loader.close();
        } catch (IOException | ClassNotFoundException | IllegalAccessException | IllegalArgumentException | InvocationTargetException | NoSuchMethodException | SecurityException | InstantiationException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        enableColor();
        final String ANSI_RED = "\u001B[31m";
        System.out.println("Demo: " + ANSI_RED + "red");
    }
}

This is a reflection implementation of https://stackoverflow.com/questions/52767585/how-can-you-use-vt100-escape-codes-in-java-on-windows. This enables a Java console program to use ANSI colors on the Windows command line, without setting VirtualTerminalLevel.

IMPORTANT: If it is possible to include additional JARs on the classpath, it is highly recommended to use the original StackOverflow code. Not only will it be faster, it also does not require internet access (to download the JARs), and has much cleaner code. However, for projects (assignments) where you are only allowed to submit one file, this can do the job.

To use: simply add the call to enableColor() anywhere before the first print statement with color. Typically, right at the start of main will work.

Demo (with color enabled):

Demo (without enabling color):