Java error Implicit super constructor is undefined for default constructor

Question

I have a some simple Java code that looks similar to this in its structure   abstract public class BaseClass       String someString      public BaseClass String someString            this someString   someString            abstract public String getName       public class ACSubClass extends BaseClass       public ASubClass String someString            super someString             public String getName             return  name value for ASubClass             I will have quite a few subclasses of BaseClass  each implementing the getName   method in its own way  template method pattern    This works well  but I don t like having the redundant constructor in the subclasses  It s more to type and it is difficult to maintain  If I were to change the method signature of the BaseClass constructor  I would have to change all the subclasses   When I remove the constructor from the subclasses  I get this compile-time error   Implicit super constructor BaseClass   is undefined for default constructor  Must define an explicit constructor  Is what I am trying to do possible

User · Answer

You could also get this error when JRE is not set. If so, try adding JRE System Library to your project.

Under Eclipse IDE:

open menu Project --> Properties, or right-click on your project in Package Explorer and choose Properties (Alt+Enter on Windows, Command+I on Mac)
click on Java Build Path then Libraries tab
choose Modulepath or Classpath and press Add Library... button
select JRE System Library then click Next
keep Workspace default JRE selected (you can also take another option) and click Finish
finally press Apply and Close.

User · Answer

I have resolved above problem as follows   Click on Project  click on properties  gt  Java Build Path  gt  Library  gt  JRE System Library  gt  Edit Select default system JRE And Finish Apply and close

User · Answer

Sorry for necroposting but faced this problem just today  For everybody also facing with this problem - one of he possible reasons - you don t call super at the first line of method  Second  third and other lines fire this error  Call of super should be very first call in your method  In this case everything is well

User · Answer

Eclipse will give this error if you don t have call to super class constructor as a first statement in subclass constructor

User · Answer

Another way is call super   with the required argument as a first statement in derived class constructor   public class Sup       public Sup String s            public class Sub extends Sup       public Sub     super  hello

User · Answer

You get this error because a class which has no constructor has a default constructor  which is argument-less and is equivalent to the following code   public ACSubClass         super        However since your BaseClass declares a constructor  and therefore doesn t have the default  no-arg constructor that the compiler would otherwise provide  this is illegal - a class that extends BaseClass can t call super    because there is not a no-argument constructor in BaseClass   This is probably a little counter-intuitive because you might think that a subclass automatically has any constructor that the base class has   The simplest way around this is for the base class to not declare a constructor  and thus have the default  no-arg constructor  or have a declared no-arg constructor  either by itself or alongside any other constructors   But often this approach can t be applied - because you need whatever arguments are being passed into the constructor to construct a legit instance of the class

User · Answer

You can solve this error by adding an argumentless constructor to the base class  as shown below     Cheers     abstract public class BaseClass              ADD AN ARGUMENTLESS CONSTRUCTOR TO THE BASE CLASS         public BaseClass                       String someString          public BaseClass String someString                this someString   someString                    abstract public String getName           public class ACSubClass extends BaseClass       public ASubClass String someString            super someString             public String getName             return  name value for ASubClass

User · Answer

It is possible but not the way you have it   You have to add a no-args constructor to the base class and that s it   public abstract class A       private String name      public A            this name   getName              public abstract String getName          public String toString            return  simple class name      this getClass   getSimpleName       name       this name                 class B extends A       public String getName            return  my name is B             public static void main  String    args             System out println  new C              class C extends A       public String getName             return  Zee             When you don t add a constructor   any   to a class the compiler add the default no arg contructor for you   When the defualt no arg calls to super    and since you don t have it in the super class you get that error message   That s about the question it self    Now  expanding the answer   Are you aware that creating a subclass   behavior   to specify different a different value   data   makes no sense       I hope you do   If the only thing that is changes is the  name  then a single class parametrized is enough   So you don t need this   MyClass a   new A  A    MyClass b   new B  B    MyClass c   new C  C    MyClass d   new D  D      or   MyClass a   new A       internally setting  A   B    C  etc  MyClass b   new B    MyClass c   new C    MyClass d   new D      When you can write this   MyClass a   new MyClass  A    MyClass b   new MyClass  B    MyClass c   new MyClass  C    MyClass d   new MyClass  D         If I were to change the method signature of the BaseClass constructor  I would have to change all the subclasses    Well that s why inheritance is the artifact that creates HIGH coupling  which is undesirable in OO systems   It should be avoided and perhaps replaced with composition   Think if you really really need them as subclass  That s why you see very often interfaces used insted    public interface NameAware        public String getName           class A implements NameAware      class B implements NameAware      class C     etc     Here B and C could have inherited from A which would have created a very HIGH coupling among them  by using interfaces the coupling is reduced  if A decides it will no longer be  NameAware  the other classes won t broke   Of course  if you want to reuse behavior this won t work

User · Answer

Short answer  Add a constructor with no argument in base parent super class  i e for example          class Parent           String name      int age      String occupation                empty constructor             public Parent                                    public Parent String name  int age  String employment       this name   name      this age   age      this occupation   employment              You can have any additional constructors as you wish aka constructor overloading here in parent class  If a super class does not have the no-argument constructor then you will get the compile-time error  Object does have such the constructor  so if Object is a only super class then there is no problem     then let s inherit     class Child extends Parent                Child String name  int age   this name   name  this age   age                    With super    a super class no-argument constructor is called and with super parameter list   a super class constructor with the matching parameter list is called

User · Answer

I had this error and fixed it by removing a thrown exception from beside the method to a try catch block  For example   FROM   public static HashMap lt String  String gt  getMap   throws SQLException        TO    public static Hashmap lt String String gt  getMap       try      catch SQLException

User · Answer

For those who Google for this error and arrive here  there might be another reason for receiving it  Eclipse gives this error when you have project setup - system configuration mismatch   For example  if you import Java 1 7 project to Eclipse and you do not have 1 7 correctly set up then you will get this error  Then you can either go to Project - Preference - Java - Compiler and switch to 1 6 or earlier  or go to Window - Preferences - Java - Installed JREs and add fix your JRE 1 7 installation

[java] Java error: Implicit super constructor is undefined for default constructor

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