"Implicit super constructor character() is undefined. Must explicitly invoke another constructor." Error

Question

So I have a class called character(), and my second class ChooseCharacterGUI() extends that class, but when I try to initialize ChooseCharacterGUI() to create the application I get the error "Implicit super constructor character() is undefined. Must explicitly invoke another constructor."

This is the ChooseCharacterGUI() class.

public class ChooseCharacterGUI extends character {

final String CharacterChoice;
private JFrame frame;
private JPanel ChooseCharacterMenu;
private JPanel Home;


// Launches  application.
public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                ChooseCharacterGUI window = new ChooseCharacterGUI();
                window.frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

//Creates application 
public ChooseCharacterGUI() {
    initialize();
}

Anyone know how I can fix this? thanks.

By invoking another constructor, as the error message suggests. — Robert Harvey, Mar 15 '15 at 00:14
It seems that you character class does not have a default constructor, and you should explicitly call it's constructor in constructor of derived class — Vladislav Lezhnin, Mar 15 '15 at 00:14
Your `character` class has no non-argument constructor, so you need to call the provided constructor explicitly. — Tom, Mar 15 '15 at 00:15
There are at least 3 ways to fix it. (1) By writing a constructor for `character` with no arguments, (2) By writing a constructor for `ChooseCharacterGUI` that invokes a constructor of `character`, (3) by removing the words `extends character`. It is difficult to know without more information which is the right thing to do. — Paul Boddington, Mar 15 '15 at 00:27
This is a common "Java newbie" problem; see link. The only other thing to add is that naming a class `character` is a Java style violation. But don't change it to `Character` because that is a standard class name ... and "borrowing" can lead to readability issues. — Stephen C, Mar 15 '15 at 00:38

score 0 · Answer 1 · answered Mar 15 '15 at 00:25

Most likely your character class has a parameterised constructor and no default constructor. E.g.

class character {
     public character(String someargument) { ... }
}

So your CharacterGUI class needs to have in its default constructor a call to the parameterised constructor of the super class. E.g.

class CharacterGUI {
     public CharacterGUI() {
         super("somedefaultvalue");
     }
}

Perhaps another concern is that your super class has a lowercase first letter, which is confusing, and you're inheriting this in the class which also has the main function. This code might need a bit of refactoring when you've got it working.

This is the code from my character class - `public character (String iName, String iGender){` I just added this code to my ChooseCharacterGUI() constructor and it seems to have worked - `public ChooseCharacterGUI() { super("test", "Male"); initialize(); }` — Nemo, Mar 15 '15 at 00:35

score 0 · Answer 2 · answered Mar 15 '15 at 00:31

Every class you write must have a constructor, and every constructor must invoke super. If you don't write a constructor, Java generates one with no arguments that does nothing but call super(). If you write a constructor but don't have a super call, Java inserts an invisible super() at the top. So if either of these automatic things is happening and the super class doesn't have a no-args constructor (called a default constructor), you get this error.

So your character class must not have a default constructor. Either write one, or in your CharacterGUI class, call whatever character constructor you have.

I strongly suspect that you don't actually want to have CharacterGUI extend character though. And also, by convention, character should be capitalized.

"Implicit super constructor character() is undefined. Must explicitly invoke another constructor." Error

2 Answers2