Calling a base class constructor from derived class in Java

Question

I have a class as follows:

public class Polygon  extends Shape{      private int noSides;     private int lenghts[];      public Polygon(int id,Point center,int noSides,int lengths[]) {         super(id, center);         this.noSides = noSides;         this.lenghts = lengths;     } } 

Now a regular polygon is a polygon whose all sides are equal. What should be the constructor of my regular polygon?

public Regularpolygon extends Polygon{  //constructor ??? } 

Answer 1

public class Polygon  extends Shape {         private int noSides;     private int lenghts[];      public Polygon(int id,Point center,int noSides,int lengths[]) {         super(id, center);         this.noSides = noSides;         this.lenghts = lengths;     } }  public class RegularPolygon extends Polygon {     private static int[] getFilledArray(int noSides, int length) {         int[] a = new int[noSides];         java.util.Arrays.fill(a, length);         return a;     }      public RegularPolygon(int id, Point center, int noSides, int length) {         super(id, center, noSides, getFilledArray(noSides, length));     } } 

Answer 2

class Foo {     Foo(String str) { } }  class Bar extends Foo {     Bar(String str) {         // Here I am explicitly calling the superclass          // constructor - since constructors are not inherited         // you must chain them like this.         super(str);     } }