Why only String[] args in java instead of Object[] args?

Question

In java, as per the Java Language Specification 12.1.4 the main method should be declared as follows:

public static void main(String[] args){
     //code of program
}

With the use of String[] args we can get command-line arguments. Sometime those command-line arguments needs to be converted to appropriate type. suppose if you have supplied any number 123 as an argument and you want to convert it to int then we can use one of the following conversion methods:

int n1=Integer.valueOf(args[0]);
//or
int n2=Integer.parseInt(args[0]);

But, if java could have provided use of Objects[] args instead String[] args then we can easily convert from one type to another, for this example conversion would take place as follows:

public static void main(Object[] args){
     int n1=(Integer)args[0];
}

I'm not getting this why java have used String[] args and not Object[] args?

The command line provides strings. How would you distinguish between a string and an integer? Just being a numerical value is not enough to deem it an integer. — Jeroen Vannevel
– Jeroen Vannevel, Commented Nov 26, 2013 at 3:25
Ravi - It is good to think beyond the boundaries of what we do currently. FYI - Powershell/.NET/C#/Cmdlets can actually do something like this msdn.microsoft.com/en-us/library/ms714395%28v=vs.85%29.aspx crazorsharp.blogspot.com/2009/12/… — mikey
– mikey, Commented Nov 26, 2013 at 3:36

Sergey Kalinichenko · Accepted Answer · 2013-11-26 03:30:58Z

7

Java is designed with portability in mind, so that Java programs would be invoked by diverse operating environments. Having the environments pass Java objects to main would put too much restrictions on the caller system, because that system would have a task of "understanding" the input and converting it to Java objects.

Strings, on the other hand, are universal: all operating environments have them. Therefore, Java specification required strings, knowing that your Java program would be able to process and understand them better than an external environment.

answered Nov 26, 2013 at 3:30

Sergey Kalinichenko

729k85 gold badges1.2k silver badges1.6k bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Jorge Campos · Accepted Answer · 2019-05-16 17:07:00Z

3

This is simple because the args came from outside java environment, it is from the Operating System and as such it can't create Java Objects it can only pass Strings

To call a java program from a console it would be something like:

c:\java MyProgram 123

There is no way to java know that the OS is passing an object it is just a string.

edited May 16, 2019 at 17:07

answered Nov 26, 2013 at 3:27

Jorge Campos

23.8k7 gold badges65 silver badges95 bronze badges

Comments

Sudhakar Tillapudi · Accepted Answer · 2013-11-26 03:25:54Z

2

whenever you read from Console it is by default String that is the reason they have made it as String[] array .

if you use :

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
System.out.print("Enter String");
String str = br.readLine();

String variable str by contains String because br.ReadLine() gives you string

answered Nov 26, 2013 at 3:25

Sudhakar Tillapudi

26.3k5 gold badges43 silver badges70 bronze badges

Comments

Steve P. · Accepted Answer · 2013-11-26 03:27:22Z

1

Because you cannot pass an object via a command line argument. Instead, it's natural to interpret the passed arguments as Strings.

answered Nov 26, 2013 at 3:27

Steve P.

14.7k9 gold badges46 silver badges74 bronze badges

Comments

HJW · Accepted Answer · 2013-11-26 03:28:16Z

1

public static void main(String[] args) is a main method that runs when you execute the Class file $java MyClass input1 input2.

answered Nov 26, 2013 at 3:28

HJW

23.5k51 gold badges147 silver badges218 bronze badges

Comments

Elliott Frisch · Accepted Answer · 2013-11-26 03:30:35Z

1

Because the operating system doesn't pass variable typed arguments to the JVM. If you had Object[] args the JVM couldn't really infer their types like that without the Operating System. It's also the general contract (in Java of course) of "standard" (e.g. ancestral C/C++) Main function.

answered Nov 26, 2013 at 3:30

Elliott Frisch

202k20 gold badges166 silver badges265 bronze badges

Comments

Kishore · Accepted Answer · 2013-11-26 03:40:09Z

1

May be because "String" is an array of char sequence which takes continuous memory, and which can be entered using standard keyboard. Otherwise how main method will handle type casting.

answered Nov 26, 2013 at 3:40

Kishore

3003 silver badges14 bronze badges

Collectives™ on Stack Overflow

Why only String[] args in java instead of Object[] args?

7 Answers 7

Comments

Comments

Comments

Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

7 Answers 7

Comments

Comments

Comments

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related