Command Line Arguments In Java With Examples | Tutorials

Command line arguments is a methodology which user will give inputs through the console using commands. Whatever the concept that you preferred to learn in java , we are highly recommended to go through the examples. In reality , theoretical carries a just 20% of the subject , practically carries a lot more than 80%. Fewer technical words ! More Examples !

Table Of Contents # 1 :

Command Line Arguments – Def, Syntax, Examples

In fact command line arguments are using just for a subject purpose and may be it is used in advance java core system in order to build the applications, just an expectation. Since , there may be a lot of ways to execute the program.

But , it is necessary that you need to know as a newbie about command line arguments.What are command line arguments?

The console is an interface between the user and program.

When a user enters the inputs on the console using commands, we sending the input as an argument to the main method in java that’s why in public static void main() we creating a string array to store values which work at executing time.

> In simple words , it’s just an another form of method that was used back in 2000’s year where scanner function was not introduced.

After all that a new JDK was updated further by a scanner function was implemented in order to solve the problems much more confidently.

The main difference here it has when passing the command line inputs as arguments. The inputs were directly written with the execution file command.

Thereby the function-calls the value directly from the main method ( string args[]). For instance , command line arguments are executed and compiles as follows :

• Compile method : Javac filename.java
• Execution method : java class name arguments

 

Example Code : 1 ( # Without command line arguments # Check output )

Output #1 :

Example code # 2 : With command line arguments : 

Output # 2 :

// Here Command line Arguments are 10,20 and these values are stored as an array and those values were sent to the main function. In order to get that values, we are using the method called ” string args[] ” as a formal argument. 

Example code# 3 : Another Example same as like # Example # 2 :

Output #3 :

Example code # 4 : (Sample Error Program )

Output : 

So you get an idea how to take command line arguments in java.

What Is Parse Method ?

# Syntax for a command line arguments for the conversion of a string into a number( 0,1,2,3,…N) ” Parse Method “. From the following example, you will likely to learn how to pass the command line arguments as inputs with examples. Have a look.

# PARSE #

PARSE : It is a method which take a string(input) as an argument and convert in other formats as like :

• Integer
• Float
• Double

THE TYPES OF PARSE METHODS :

• parseInt();
• parseDouble();
• parseFloat();

THE FUNCTIONS OF PARSE METHODS :

• ParseInt(); – It is a member function in Integer Class;
• ParseDouble(); – It is a member function in Double Class;
• ParseFloat(); – It is a member function in Float Class;

 

HOW TO PASS COMMAND LINE ARGUMENTS IN JAVA WITH EXAMPLES :

Every parse method has the same syntax but the difference is changes when the data variables changes and methodology. The conversion of a given string input can convert into different formats , as a programmer it’s all up to you which one to use according to program Int, Double , Float ( Double and Float are equal )

>> Example : ( Parse Int )

      Syntax:Integer.parseInt(String s);

Example1: String s=”156″; //156 is not a number it is string;
System.out.println(s+1); //output:1561 :”156″+1=1561 string concatenation.

int x=Integer.parseInt(“156”);
System.out.println(x+1); //output:157 :156+1=157

>> Example : ( Parse Double )

      Syntax:Double.parseDouble(String s);

Example : 2

String s=”156.5″; //156.5 is not a number it is a string;
System.out.println(s+1); //output:1561 :”156.5″+1=156.51 string concetation

double x=Double.parseDouble(“156.5”);
System.out.println(x+1); //output:157.5:156.5+1=157.5

// Double Function is as same as Float // The main difference is , where double is 8-Bytes and float is 4- Bytes. It’s all up to you which one to choose.

 Below are the examples in order to convert the given string (integer) as an integer , or double , float.

 // Conversion of String into Integer Without Parse Method // Check Out The Output //

Example program# 1 : ( Without Parse ) 

Output : 

Error : When the user is given a number , the system won’t understand that it was a number instead of, it considers it has a string. If we suppose to add anything to that it become concatenation ex :args[0]+1=”10″+1=101

In order to get rid of that error , we are using a method called parse .Check out how the program works with the help of parse method :

Example program # 2:  ( With Parse ) : 

Output : 

// That’s How the Parse method works //.

If you have any doubts related to command line arguments , do comment here. We will help you out.