generated Xpand code ' editor does not contain a main type'. However I have a main method

Question

I am trying to understand dsl code generation with xText and xPand.

I have opened the statemachine xText example in eclipse and ran as a new eclipse application. I then made a java contaning a test.statemachine file in the src and copied the supplied code into it.

The following .java file is then generated in the src-gen folder:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class testing {

public static void main(String[] args) {
    new testing().run();
}

protected void doUnlockPanel() {
    System.out.println("Executing command unlockPanel (PNUL)");
}
protected void doLockPanel() {
    System.out.println("Executing command lockPanel (PNLK)");
}
protected void doLockDoor() {
    System.out.println("Executing command lockDoor (D1LK)");
}
protected void doUnlockDoor() {
    System.out.println("Executing command unlockDoor (D1UL)");
}

protected void run() {
    boolean executeActions = true;
    String currentState = "idle";
    String lastEvent = null;
    while (true) {
        if (currentState.equals("idle")) {
            if (executeActions) {
                doUnlockDoor();
                doLockPanel();
                executeActions = false;
            }
            System.out.println("Your are now in state 'idle'. Possible events are [doorClosed].");
            lastEvent = receiveEvent();
            if ("doorClosed".equals(lastEvent)) {
                currentState = "active";
                executeActions = true;
            }
        }
        if (currentState.equals("active")) {
            if (executeActions) {
                executeActions = false;
            }
            System.out.println("Your are now in state 'active'. Possible events are [drawOpened, lightOn].");
            lastEvent = receiveEvent();
            if ("drawOpened".equals(lastEvent)) {
                currentState = "waitingForLight";
                executeActions = true;
            }
            if ("lightOn".equals(lastEvent)) {
                currentState = "waitingForDraw";
                executeActions = true;
            }
        }
        if (currentState.equals("waitingForLight")) {
            if (executeActions) {
                executeActions = false;
            }
            System.out.println("Your are now in state 'waitingForLight'. Possible events are [lightOn].");
            lastEvent = receiveEvent();
            if ("lightOn".equals(lastEvent)) {
                currentState = "unlockedPanel";
                executeActions = true;
            }
        }
        if (currentState.equals("waitingForDraw")) {
            if (executeActions) {
                executeActions = false;
            }
            System.out.println("Your are now in state 'waitingForDraw'. Possible events are [drawOpened].");
            lastEvent = receiveEvent();
            if ("drawOpened".equals(lastEvent)) {
                currentState = "unlockedPanel";
                executeActions = true;
            }
        }
        if (currentState.equals("unlockedPanel")) {
            if (executeActions) {
                doUnlockPanel();
                doLockDoor();
                executeActions = false;
            }
            System.out.println("Your are now in state 'unlockedPanel'. Possible events are [panelClosed].");
            lastEvent = receiveEvent();
            if ("panelClosed".equals(lastEvent)) {
                currentState = "idle";
                executeActions = true;
            }
        }
        if ("doorClosed".equals(lastEvent)) {
            System.out.println("Resetting state machine.");
            currentState = "idle";
            executeActions = true;
        }

    }
}

private String receiveEvent() {
    System.out.flush();
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    try {
        return br.readLine();
    } catch (IOException ioe) {
        System.out.println("Problem reading input");
        return "";
    }
}
}

However this will not fun with the error 'editor does not contain a main type' but from what I can see this exists

Answer 1

The folder src-gen which contains the generated testing.java is by default a plain folder , not a "source folder". So so must open the context menu on that folder and select "Build Path" -> "Use as source-folder". After that you can execute the Java program.