Java
In this tutorial we will learn about command line arguments in Java programming language.
Since the beginning of this tutorial series we have been writing the main method like the following.
main
class NameOfTheClass { public static void main(String[] args) { // some code... } }
Note! The parameter list of the main method is String[] args.
String[] args
So, we have a variable args which is an array of String.
args
When, we run our program we can pass some arguments to our code from the command line and it will be saved in this args variable which we can later use in our code.
java cmdLine command_list
Where, cmdLine is the name of the class and command_list is the list of arguments passed to the class.
cmdLine
command_list
Note! The first command line argument is stored at index 0, the second one is stored at index 1 and so on.
Note! All command line arguments are passed as string.
class Example { public static void main(String[] args) { // total number of arguments passed int len = args.length; System.out.println("Total number of arguments: " + len); } }
Output:
$ javac Example.java $ java Example Total number of arguments: 0 $ java Example Hello World Total number of arguments: 2 $ java Example My name is Yusuf Shakeel Total number of arguments: 5
class Example { public static void main(String[] args) { // total number of arguments passed int len = args.length; System.out.println("Total number of arguments: " + len); System.out.println("Arguments:"); for(int i = 0; i < len; i++) { System.out.println("Index: " + i + " Arg: " + args[i]); } } }
$ javac Example.java $ java Example My name is Yusuf Shakeel Total number of arguments: 5 Arguments: Index: 0 Arg: My Index: 1 Arg: name Index: 2 Arg: is Index: 3 Arg: Yusuf Index: 4 Arg: Shakeel
For this we will use the equals method provided by the String class.
equals
class Example { public static void main(String[] args) { // total number of arguments passed int len = args.length; // check strings provided if (len < 2) { System.out.println("Two strings required."); } else { // check if provided strings are equal if (args[0].equals(args[1])) { System.out.println("Strings are equal."); } else { System.out.println("Strings are not equal."); } } } }
$ javac Example.java $ java Example Two strings required. $ java Example Hello Two strings required. $ java Example Hello World Strings are not equal. $ java Example Hello hello Strings are not equal. $ java Example Hello Hello Strings are equal.