How to find the number of parameters provided by runtime in Java?

In Java, one way to pass parameters at runtime is to use the command line or terminal. When retrieving these values ​​for command line arguments, we may need to find the number of arguments provided by the user at runtime, which can be accomplished with the help of the length property. This article aims to explain the process of passing and getting a user-supplied number of parameters with the help of a sample program.

Get the number of parameters provided by the user at runtime

Before finding the number of command line arguments, our first step is to create a program that allows the user to pass arguments at run time.

String[] parameters

When writing Java programs, we often encounter the main() method. When the JVM calls this method, the Java application begins execution. It is used with an argument called String[] args, which accepts an argument of type String. It allows us to pass parameters through the terminal and store these parameters in a string array. We can say that String[] args is a command line argument.

Example 1

The following example will illustrate how to pass parameters from the terminal to a Java program.

public class Arg {
   public static void main(String []args){
      // for each loop to print argument taken from terminal
      for(String arg : args) { 
          System.out.println(arg);
      }
   }
}

Output

To compile the code by entering the command from the terminal: javac Arg.java

To run the code by entering the command from the terminal: java Arg "Your String"

PS D:\Java Programs> java Arg "Hello, You are on Tutorials Point"
Hello, You are on Tutorials Point

So far, we have seen how to get parameters from the user at runtime. Now, our next step is to find the number of arguments passed.

As mentioned before, to find the number of arguments passed by the user at runtime, we can use the length property of String[] args.

Example 2

This example illustrates how to use the length property to get the number of arguments.

public class Arg {
   public static void main(String []args) {
      // for each loop to print argument taken from terminal
      System.out.println("List of arguments passed by user: ");
      for(String arg : args) {  
	     System.out.print(arg);
      }
      System.out.println();
      // to print the length of argument
      System.out.println("Number of arguments passed by user: " + args.length);
   }
}

Output

PS D:\Java Programs> java Arg "Hello! how are you"
List of arguments passed by user: 
Hello! how are you
Number of arguments passed by user: 1

If we enclose the parameter in double quotes, it will be treated as a single parameter. Therefore, we get a result of 1.

Example 3

In the following examples, we will provide input without double quotes.

public class Arg {
   public static void main(String []args) {
      // for each loop to print argument taken from terminal
      System.out.println("List of arguments passed by user: ");
      for(String arg : args) {  
	     System.out.println(arg);
      }
      // to print the length of argument
      System.out.println("Number of arguments passed by user: " + args.length);
   }
}

Output

PS D:\Java Programs> java Arg Hello! how are you
List of arguments passed by user: 
Hello!
how
are
you

When we don't use double quotes, the parameters will be processed separately.

Example 4

The following example demonstrates how to use the length property to retrieve all parameters passed through the terminal.

public class Arg {
   public static void main(String []args) {
      // for loop to print argument taken from terminal
      System.out.println("List of arguments passed by user: ");
      for (int i = 0; i < args.length; i++) {
         System.out.println("Argument " + (i + 1) + ": " + args[i]);
      }
   }
}

Output

PS D:\Java Programs> java Arg Hello! how are you
List of arguments passed by user: 
Argument 1: Hello!
Argument 2: how
Argument 3: are
Argument 4: you 

in conclusion

In this article, we learned how to find the number of arguments provided by the runtime in Java using the length property of String[] args. We also discovered the use of String[] args, which allows the user to pass arguments from the terminal to the main() method.

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