Java Command-Line Arguments

 

Java Command-Line Arguments

The command-line arguments in Java allow us to pass arguments during the execution of the program.

class Cla {

  public static void main(String[] args) {

    System.out.println("Command-Line arguments are");

 

    // loop through all arguments

    for(String str: args) {

      System.out.println(str);

    }

  }

}

 

 to run this program using the command line.

1. To compile the code

javac Cla.java

2. To run the code

java Cla

Now suppose we want to pass some arguments while running the program, we can pass the arguments after the class name. For example,

java Cla MY NAME IS ABCD

arguments passed to the program through the command line. Now, we will get the following output.

Command-Line arguments are

MY

NAME

IS

ABCD

 

In the above program, the main() method includes an array of string named args as its parameter.

The String array stores all the arguments passed through the command line.

Passing Numeric Command-Line Arguments

The main() method of every Java program only accepts string arguments. Hence it is not possible to pass numeric arguments through the command line.

However, we can later convert string arguments into numeric values.

Example: Numeric Command-Line Arguments

class Ncla {

  public static void main(String[] args)

 {

    for(String str: args) {

      // convert into integer type

    int argument = Integer.parseInt(str);

    System.out.println("Argument in integer form: " + argument);

    }

  }

}

Let's try to run the program through the command line.

// compile the code

javac  Ncla.java

 

// run the code

java  Ncla 12 34

Here 12 and 34 are command-line arguments. Now, we will get the following output.

Arguments in integer form

12

34

In the above example, notice the line

int argument = Intege.parseInt(str);

Here, the parseInt() method of the Integer class converts the string argument into an integer.

Similarly, we can use the parseDouble() and parseFloat() method to convert the string into double and float respectively.