Question

well I’m wondering if it’s possible to have a method where another method is passed as a parameter, so the first method can call the method passed in param?

Like for instance:

public void goToVisitManagementForm() throws ParseException {
    if (isAuthenticated() && userTypeIs("Patient")) {

         // I could have this whole block just moved to another method?
        Panel newPanel = new Panel("Choose the details for your visit");
        Component visitManagementForm = new VisitManagementForm(userData,
                this);
        newPanel.addComponent(visitManagementForm);
        mainWindow.setMainPanel(newPanel);

    } else {
        authenticate();
    }
}

If the code block would be moved to another method and it would be passed as a parameter to this method. How can I achieve that and is this a good practice? Because in this case I have the ifs that I always need to paste in…
What about other aspects of this?

Answer 1

This is called a higher-order function and you cannot do this in Java 7 or below. You can simulate passing functions to other functions through the use of an anonymous class that instantiates some interface the function expects, and then calling the function on that object.

For example, to pass a no-arg function:

interface Function {
    void apply();
}

void takesAFunction(Function function) {
    function.apply();
}

Then the following code snippet would do what you want:

Function myFunction = new Function() {
    @Override
    public void apply() {
        // your code here.
    }
};
takesAFunction(myFunction);

As a side note, reflection is extreme overkill for this type of problem.