is it possible for a class in java to have no constucror...

Replies

• 

  Anoop Kumar

  Didn't used javap command..
  but default constructor always added to class file, either it written in source code or not. did you tried for it JD java decompiler to generate source file from class file.
  
  If you have any doubt just call super(); as first line in subclass *constructor without having any constructor in super class. see what will happen!!!!😀
• 

  Neeraj Sharma

  No need at all. There is always a default constructor as follows even if you dont declare yours,
  It has following structure.
  public class_name
  {
  }
• 

  sookie

  #-Link-Snipped-# I am getting the default constructor getting displayed for my java class using javap. Can you please share your java class along with javap command results?
• 

  Vikash Verma

  getting following error while using super(); in subclass constructor...😎
  
  C:\Users\VIK\Desktop>javac *.java
  B.java:6: cannot find symbol
  symbol : constructor A()
  location: class A
  super();
  ^
  1 error
• 

  Vikash Verma

  I am getting no constructor using javap tool in my, class here goes the output of my class... 😎
  
• 

  Anoop Kumar

  your code please...
• 

  Vikash Verma

  #-Link-Snipped-# does it always happen that for each and every java program javap tool will display at least one constructor...😎
• 

  Anoop Kumar

  Vikash Verma

  #-Link-Snipped-# does it always happen that for each and every java program javap tool will display at least one constructor...😎

  Sure it will show you all class members using command javap -private
  If your code is like this one
  

  class super1{
  }
  public class HelloWorld extends super1{
      HelloWorld (String s)    {
            s="ABC"    ;
          }
  public static void main(String[] args) {
          System.out.println("Hello, World");
      }
  }
  

  Then compile the code and use javap you will get following output
  

  C:\Documents and Settings\\My Documents\Downloads>javap -private Hell
  oWorld
  Compiled from "HelloWorld.java"
  public class HelloWorld extends super1{
      HelloWorld(java.lang.String);
      public static void main(java.lang.String[]);
  }
  

  For class super1.
  

  C:\Documents and Settings\\My Documents\Downloads>javap -private supe
  r1
  Compiled from "HelloWorld.java"
  class super1 extends java.lang.Object{
      super1();
  }

• 

  Vikash Verma

  This is what my code is displaying...😎
  
  C:\Users\VIK\Desktop>javac B.java
  
  C:\Users\VIK\Desktop>javap B
  Compiled from "B.java"
  class B extends java.lang.Object{
  public static void main(java.lang.String[]);
  }
• 

  sookie

  Vikash Verma

  This is what my code is displaying...😎
  
  C:\Users\VIK\Desktop>javac B.java
  
  C:\Users\VIK\Desktop>javap B
  Compiled from "B.java"
  class B extends java.lang.Object{
  public static void main(java.lang.String[]);
  }

  And can you Please tell what is your code? B.java?
• 

  sookie

  I was just trying something and came to know that may be your B.java has declared constructor as "private" If you have its visibility as "private" then following command "javap B" will not show the private constructor. In order to view it you will have t explicitly run the command as "javap -private B".
• 

  Anoop Kumar

  my JDK giving error while running javap B.
  While "javap -private B". is working fine.
  #-Link-Snipped-# , can you confirm this.
• 

  sookie

  ianoop

  my JDK giving error while running javap B.
  While "javap -private B". is working fine.
  #-Link-Snipped-# , can you confirm this.

  show me the error and your B.java ?
• 

  Anoop Kumar

  sookie

  show me the error and your B.java ?

  😲, its working, what's wrong , I was doing
  
  Here is final conclusion
  

   
   
  With public constructor
  Source:
  public class abc{
     
      abc(){}   
      public static void main(String[] args) {
          System.out.println("Hello, World");
      }
   
  }
  Output
   
  C:\Documents and Settings\\My Documents\Downloads>javap  abc
  Compiled from "abc.java"
  public class abc extends java.lang.Object{
      public abc();
      public static void main(java.lang.String[]);
  }
   
  With private constructor
  Source:
  public class abc{
     
      private abc(){}   
      public static void main(String[] args) {
          System.out.println("Hello, World");
      }
   
  }
  Output
   
  C:\Documents and Settings\\My Documents\Downloads>javap  abc
  Compiled from "abc.java"
  public class abc extends java.lang.Object{
      public static void main(java.lang.String[]);
  }
   
  With private constructor
  C:\Documents and Settings\\My Documents\Downloads>javap -private abc
  Compiled from "abc.java"
  public class abc extends java.lang.Object{
      private abc();
      public static void main(java.lang.String[]);
  }

• 

  sookie

  ianoop

  😲, its working, what's wrong , I was doing

  Cool...😀
• 

  Vikash Verma

  #-Link-Snipped-# you are right...😎