Java Implicit super constructor Employee is undefined Must explicitly invoke another constructor

Question

Hello I m new to Java  I m getting this error in my production worker class  My Production worker constructor says explicitly invoke another constructor  I don t know what to do    import java util Date   public class Employee         private String name  number        private Date date         public Employee String name  String number  Date date                      setName name               setNumber number               setDate date                  public void setName String n                      name   n                public void setNumber String n                      number   n                 you can check the format here for correctness               public void setDate Date d                      date   d                 public String getName                       return name                public String getNumber                       return number                public Date getDate                       return date               public class ProductionWorker extends Employee         private int shift        private double hourlyrate            error is here  Implicit super constructor Employee   is undefined  Must explicitly invoke another constructor         public ProductionWorker int shift  double hourlyrate                      setShift shift               setHourlyPayRate hourlyrate                  public void setShift int s                      shift   s                public void setHourlyPayRate double rate                      hourlyrate   rate                 public int getShift                       return shift                public double getHourlyPayRate                       return hourlyrate

User · Answer

As others have already mentioned you are required to provide a default constructor public Employee(){} in your Employee class.

What happens is that the compiler automatically provides a no-argument, default constructor for any class without constructors. If your class has no explicit superclass, then it has an implicit superclass of Object, which does have a no-argument constructor. In this case you are declaring a constructor in your class Employee therefore you must provide also the no-argument constructor.

Having said that Employee class should look like this:

Your class Employee

import java.util.Date;

public class Employee
{
      private String name, number;
      private Date date;

      public Employee(){} // No-argument Constructor

      public Employee(String name, String number, Date date)
      {
            setName(name);
            setNumber(number);
            setDate(date);
      }

      public void setName(String n)
      {
            name = n;
      }
      public void setNumber(String n)
      {
            number = n;
            // you can check the format here for correctness
      }
      public void setDate(Date d)
      {
            date = d;
      }

      public String getName()
      {
            return name;
      }
      public String getNumber()
      {
            return number;
      }
      public Date getDate()
      {
            return date;
      }
}

Here is the Java Oracle tutorial - Providing Constructors for Your Classes chapter. Go through it and you will have a clearer idea of what is going on.

User · Answer

This problem can also come up when you don t have your constructor immediately call super   So this will work     public Employee String name  String number  Date date          super             But this won t     public Employee String name  String number  Date date             an example of  any  code running before you call super      if  number  lt  5               number               super             The reason the 2nd example fails is because java is trying to implicitely call   super name number date    as the first line in your constructor     So java doesn t see that you ve got a call to super going on later in the constructor  It essentially tries to do this     public Employee String name  String number  Date date          super name  number  date        if  number  lt  5               number               super             So the solution is pretty easy    Just don t put code before your super call  -  If you need to initialize something before the call to super  do it in another constructor  and then call the old constructor    Like in this example pulled from this StackOverflow post   public class Foo       private int x       public Foo                 this 1              public Foo int x                this x   x

User · Answer

An explicit call to a parent class constructor is required any time the parent class lacks a no-argument constructor  You can either add a no-argument constructor to the parent class or explicitly call the parent class constructor in your child class

User · Answer

Had this problem recently in my comp lab  It s simple and Erkan answered it correctly  Just put super  the name of your subclass   So in relation to your problem --  super  ProductionWorker   as the first line of your subclass  constructor

User · Answer

ProductionWorker extends Employee  thus it is said that it has all the capabilities of an Employee  In order to accomplish that  Java automatically puts a super    call in each constructor s first line  you can put it manually but usually it is not necessary  In your case  it is necessary because the call to super    cannot be placed automatically due to the fact that Employee s constructor has parameters   You either need to define a default constructor in your Employee class  or call super  Erkan   21  new Date     in the first line of the constructor in ProductionWorker

User · Answer

Any constructor for any class as you know creates an object  So  the constructor should contain proper initialization code for its class  But if you have some class which extends another one  lets call it  parent   then constructor for the class cannot contain all the code needed for the initialization by definition  for example  you cannot define private fields of the parent   That s why constructor of the class has to call constructor of its parent  If you do not call it explicitly then the default parent constructor is called  which is without any parameter    So  in your case  you can either implement default constructor in parent or directly call any constructor in the class

[java] Java. Implicit super constructor Employee() is undefined. Must explicitly invoke another constructor

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