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Posts: 10
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public class Star extends Object {
Star(String s1){
System.out.println(s1+"is a Star");}

Star(String s2, String s3){
System.out.println(s2+"and"+s3+" are also Stars");}

public static void main(String[] args){
Sun sun=new Sun();
Sun sun1=new Sun("Venus");
Sun sun2= new Sun("Mars", "Eaarth");
class Sun extends Star{
public Sun(){System.out.println("Star Wars1");
public Sun(String v1){ super(v1,"Saturn");
System.out.println("Star Wars2");}
public Sun (String v2, String v3){
if (v2.substring(0,v2.length()).length()>v3.length())
System.out.println("Mission to Mars");
For the above code, the answer of compiling the code will be:
1. Star
2.Star Wars1
3.Mercury is a star
4.Venus and Saturn are also star
5.Star Wars2
7. Earth
My question is, when compile the third constructor in subclass Sun, Sun sun2= new Sun("Mars", "Earth"); why the line 6 Star get print out?
Thanks for attention
Posts: 121
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Your third constructor of Sun does not start with an "super();", so it is implicitly inserted by the compiler, so your constructor looks like:

This super() calls the constructor Star(), which prints out "Star". By the way, inserting an "super(v2, v3);" at the start of your thrird constructor of Sun would enforce executing the Star(String, String)-constructor. Perhaps this is what you expected.
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A good test on this is to remove the Star() constructor but leave the other two constructors in the Star class. When you try to compile the Sun class you will receive a compiler error because there is no matching constructor in Star.
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