Using an array as a parameter

Question

I do not understand the details of using an array as a parameter:

I have created an int array and a method and I do not understand why it's possible to rename the parameter as seen below from "note" to "veraenderung".

How does Java deal with parameters? Do I need a parameter even if I call the method(note)?

public class ArrayParameter {

    public static void main(String[] args) {
        int[] note = {3,2,1,4,5}; //Array
        int[] note2 = {3,2,1,4,5};
        korrektur(note);
        korrektur2(note2);
    }

    //Der Methode "korrektur" wird der int Array (note) übergeben!
    public static void korrektur (int note[]) { 
        for (int i = 0; i<note.length; i++) {
            //Sobald die for Schleife aufgerufen wird, werden die jeweiligen Werte um -1 reduziert
            note[i]-=1;                         
            System.out.println(note[i]);    
        }
    }

    //int "veraenderung" ist ein Parameter
    public static void korrektur2 (int veraenderung[]) { 
        for (int i = 0; i<veraenderung.length; i++) {
            //Sobald die for Schleife aufgerufen wird, werden die jeweiligen Werte um -1 reduziert  
            veraenderung[i]-=1;                     
            System.out.println(veraenderung[i]);
        }   
    }
}

The name that you've assigned to the int array in your main method doesn't matter for the method korrektur. All the method korrektur cares about is that it's receiving an int array when called. — Seth
– Seth, Commented Feb 28, 2017 at 7:39
You can call a variable anything you like, as long as there is only one variable with that name. — Andy Turner
– Andy Turner, Commented Feb 28, 2017 at 7:40
Note: use int[] variable, not int variable[]. The latter form is allowed to mollify c++ programmers; but the type of the variable is int[], so put the[] there. — Andy Turner
– Andy Turner, Commented Feb 28, 2017 at 7:41
parameter name should be a valid identifier in java but in method calling , we can pass same object in method no meter name of parameter is same or not compare to method declaration . — Chetan Joshi
– Chetan Joshi, Commented Feb 28, 2017 at 7:42

Jude Niroshan · Accepted Answer · 2017-02-28 07:59:25Z

1

i do not understand why it is possible to rename the parameter

korrektur and korrektur2 are just 2 different methods each of them having 2 independent signatures. They are not related whatsoever (even if the programmer can name them alike, just as you did);

The name of the parameters are just local names useful in the method block;

How do java deal with parameter? Do i need a parameter even if i call the method(note)?

Those methods parameters are mandatory ones. Hence you need to insert them in your method call.

edited Feb 28, 2017 at 7:59

Jude Niroshan

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answered Feb 28, 2017 at 7:42

Koldar

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Comments

Kimberly James · Accepted Answer · 2017-02-28 08:16:40Z

0

I will try to break it down as small as possible for you to understand :)...

When you creating the method. example: public static void korrektur2 (int veraenderung[]) the int veraenderung[] can be named whatever you want...the main thing is that you put the "int []" somewhere within the brackets so that you tell java that "hey my method take an integer array".

The name veraenderung itself is only used locally (within that method) as a reference to tell java whatever you parse into that method will act.

For example when you call the method above and said korrektur(note); . note was declared as an array before, so when you put 'note' inside the method korrektur it is the same as replacing veraenderung with note. In other words java replaces your local variable with the one you passed into the method.

And to answer your question....for now...since you created the method which takes an integer array...YES you must always "put an integer array inside" it when calling the method. I.e. every time you call the method korrektur2 or korrekturand you do not put an integer array inside it, Java would be like "hey I was created to take an integer array and do stuff with it...why are you leaving me empty ?!?!?"

I hope this solved your questions :)

answered Feb 28, 2017 at 8:16

Kimberly James

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1 Comment

vonmentzer Over a year ago

Thx for the great explanation!!

Yuriy Black · Accepted Answer · 2017-02-28 08:18:41Z

If you have seen the .class file, you'll find the parameters are the same.
you should understand the conception 'vars Scope' (may be this). Parameter 'paramArrayOfInt' have the influence korrektur(), then it be destroied. In next method ,it just new one. It's my understanding. May be wrong, welcome to discuss.

    public class ArrayParameter
{
  public static void main(String[] paramArrayOfString)
  {
    int[] arrayOfInt1 = { 3, 2, 1, 4, 5 };
    int[] arrayOfInt2 = { 3, 2, 1, 4, 5 };
    korrektur(arrayOfInt1);
    korrektur2(arrayOfInt2);
  }

  public static void korrektur(int[] paramArrayOfInt)
  {
    for (int i = 0; i < paramArrayOfInt.length; i++)
    {
      paramArrayOfInt[i] -= 1;
      System.out.println(paramArrayOfInt[i]);
    }
  }

  public static void korrektur2(int[] paramArrayOfInt)
  {
    for (int i = 0; i < paramArrayOfInt.length; i++)
    {
      paramArrayOfInt[i] -= 1;
      System.out.println(paramArrayOfInt[i]);
    }
  }
}

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