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Why is this int array not passed as an object vararg array?


What's the simplest way to print a Java array?Java arrays printing out weird numbers and textWhat is reflection and why is it useful?Is Java “pass-by-reference” or “pass-by-value”?Create ArrayList from arrayWhat is a serialVersionUID and why should I use it?How do I convert a String to an int in Java?Why is subtracting these two times (in 1927) giving a strange result?Why don't Java's +=, -=, *=, /= compound assignment operators require casting?Why is char[] preferred over String for passwords?Why is it faster to process a sorted array than an unsorted array?Why is printing “B” dramatically slower than printing “#”?






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7















I used this code. I am confused why this int array is not converted to an object vararg argument:



class MyClass 
 static void print(Object... obj) 
 System.out.println("Object…: " + obj[0]);
 

 public static void main(String[] args) 
 int[] array = new int[] 9, 1, 1;
 print(array);
 System.out.println(array instanceof Object);



I expected the output:



Object…: 9
true


but it gives:



Object…: [I@140e19d
true





java







share|improve this question



















  • 2





    The issue is that Object... means Object[] and int[] can not be converted to Object[] (int is a primitive, not an Object). However, the int[] array itself can be interpreted as Object. So you end up passing an object array Object[] with exactly one element in it, an int[]. So you have an array of arrays.

    – Zabuza
    2 hours ago


















7















I used this code. I am confused why this int array is not converted to an object vararg argument:



class MyClass 
 static void print(Object... obj) 
 System.out.println("Object…: " + obj[0]);
 

 public static void main(String[] args) 
 int[] array = new int[] 9, 1, 1;
 print(array);
 System.out.println(array instanceof Object);



I expected the output:



Object…: 9
true


but it gives:



Object…: [I@140e19d
true





java







share|improve this question



















  • 2





    The issue is that Object... means Object[] and int[] can not be converted to Object[] (int is a primitive, not an Object). However, the int[] array itself can be interpreted as Object. So you end up passing an object array Object[] with exactly one element in it, an int[]. So you have an array of arrays.

    – Zabuza
    2 hours ago














7












7








7








I used this code. I am confused why this int array is not converted to an object vararg argument:



class MyClass 
 static void print(Object... obj) 
 System.out.println("Object…: " + obj[0]);
 

 public static void main(String[] args) 
 int[] array = new int[] 9, 1, 1;
 print(array);
 System.out.println(array instanceof Object);



I expected the output:



Object…: 9
true


but it gives:



Object…: [I@140e19d
true





java







share|improve this question
















I used this code. I am confused why this int array is not converted to an object vararg argument:



class MyClass 
 static void print(Object... obj) 
 System.out.println("Object…: " + obj[0]);
 

 public static void main(String[] args) 
 int[] array = new int[] 9, 1, 1;
 print(array);
 System.out.println(array instanceof Object);



I expected the output:



Object…: 9
true


but it gives:



Object…: [I@140e19d
true





java




java






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 42 mins ago









Boann

37.8k1291123




37.8k1291123










asked 3 hours ago









JoeCrayonJoeCrayon

492




492







  • 2





    The issue is that Object... means Object[] and int[] can not be converted to Object[] (int is a primitive, not an Object). However, the int[] array itself can be interpreted as Object. So you end up passing an object array Object[] with exactly one element in it, an int[]. So you have an array of arrays.

    – Zabuza
    2 hours ago













  • 2





    The issue is that Object... means Object[] and int[] can not be converted to Object[] (int is a primitive, not an Object). However, the int[] array itself can be interpreted as Object. So you end up passing an object array Object[] with exactly one element in it, an int[]. So you have an array of arrays.

    – Zabuza
    2 hours ago








2




2





The issue is that Object... means Object[] and int[] can not be converted to Object[] (int is a primitive, not an Object). However, the int[] array itself can be interpreted as Object. So you end up passing an object array Object[] with exactly one element in it, an int[]. So you have an array of arrays.

– Zabuza
2 hours ago






The issue is that Object... means Object[] and int[] can not be converted to Object[] (int is a primitive, not an Object). However, the int[] array itself can be interpreted as Object. So you end up passing an object array Object[] with exactly one element in it, an int[]. So you have an array of arrays.

– Zabuza
2 hours ago













2 Answers
2






active

oldest

votes


















10














You're running into an edge case where objects and primitives don't work as expected.
The problem is that the actual code ends up expecting static void print(Object[]), but int[] cannot be cast to Object[]. However it can be cast to Object, resulting in the following executed code: print(new int[][]array).



You get the behavior you expect by using an object-based array like Integer[] instead of int[].






share|improve this answer






























    5














    The reason for this is that an int array cannot be casted to an Object array implicitly. So you actually end up passing the int array as the first element of the Object array.



    You could get the expected output without changing your main method and without changing the parameters if you do it like this:



    static void print(Object... obj) 
     System.out.println("Object…: " + ((int[]) obj[0])[0]);




    Output:



    Object…: 9
    true






    share|improve this answer

























      Your Answer






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      2 Answers
      2






      active

      oldest

      votes








      2 Answers
      2






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      10














      You're running into an edge case where objects and primitives don't work as expected.
      The problem is that the actual code ends up expecting static void print(Object[]), but int[] cannot be cast to Object[]. However it can be cast to Object, resulting in the following executed code: print(new int[][]array).



      You get the behavior you expect by using an object-based array like Integer[] instead of int[].






      share|improve this answer



























        10














        You're running into an edge case where objects and primitives don't work as expected.
        The problem is that the actual code ends up expecting static void print(Object[]), but int[] cannot be cast to Object[]. However it can be cast to Object, resulting in the following executed code: print(new int[][]array).



        You get the behavior you expect by using an object-based array like Integer[] instead of int[].






        share|improve this answer

























          10












          10








          10







          You're running into an edge case where objects and primitives don't work as expected.
          The problem is that the actual code ends up expecting static void print(Object[]), but int[] cannot be cast to Object[]. However it can be cast to Object, resulting in the following executed code: print(new int[][]array).



          You get the behavior you expect by using an object-based array like Integer[] instead of int[].






          share|improve this answer













          You're running into an edge case where objects and primitives don't work as expected.
          The problem is that the actual code ends up expecting static void print(Object[]), but int[] cannot be cast to Object[]. However it can be cast to Object, resulting in the following executed code: print(new int[][]array).



          You get the behavior you expect by using an object-based array like Integer[] instead of int[].







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered 3 hours ago









          KiskaeKiskae

          14.1k13243




          14.1k13243























              5














              The reason for this is that an int array cannot be casted to an Object array implicitly. So you actually end up passing the int array as the first element of the Object array.



              You could get the expected output without changing your main method and without changing the parameters if you do it like this:



              static void print(Object... obj) 
               System.out.println("Object…: " + ((int[]) obj[0])[0]);




              Output:



              Object…: 9
              true






              share|improve this answer





























                5














                The reason for this is that an int array cannot be casted to an Object array implicitly. So you actually end up passing the int array as the first element of the Object array.



                You could get the expected output without changing your main method and without changing the parameters if you do it like this:



                static void print(Object... obj) 
                 System.out.println("Object…: " + ((int[]) obj[0])[0]);




                Output:



                Object…: 9
                true






                share|improve this answer



























                  5












                  5








                  5







                  The reason for this is that an int array cannot be casted to an Object array implicitly. So you actually end up passing the int array as the first element of the Object array.



                  You could get the expected output without changing your main method and without changing the parameters if you do it like this:



                  static void print(Object... obj) 
                   System.out.println("Object…: " + ((int[]) obj[0])[0]);




                  Output:



                  Object…: 9
                  true






                  share|improve this answer















                  The reason for this is that an int array cannot be casted to an Object array implicitly. So you actually end up passing the int array as the first element of the Object array.



                  You could get the expected output without changing your main method and without changing the parameters if you do it like this:



                  static void print(Object... obj) 
                   System.out.println("Object…: " + ((int[]) obj[0])[0]);




                  Output:



                  Object…: 9
                  true







                  share|improve this answer














                  share|improve this answer



                  share|improve this answer








                  edited 2 hours ago

























                  answered 3 hours ago









                  ruoholaruohola

                  3,1902634




                  3,1902634



























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