What Are Java Command Line Arguments?<\/h3>\n
The command-line arguments in Java allow the programmers to pass the arguments during the execution of a program. The users can pass the arguments during the execution by passing the command-line arguments inside the main() method.<\/p>\n
A command-line argument is nothing but the information that we pass after typing the name of the Java program during the program execution. These arguments get stored as Strings in a String array that is passed to the main() function.<\/p>\n
We can use these command-line arguments as input in our Java program.<\/p>\n
Java Command-line arguments Example with its working<\/h4>\n
Suppose there is a java program and we compile it. During the execution of the program, we pass the command as \u201cjava MyProgram Techvidvan Java Tutorial\u201d. Here the java command is used to run the Java program in which the main function is present and,<\/p>\n
MyProgram is the name of the java file that we need to run. JVM considers the input after the program name as command-line arguments. That is, in our input command, \u201cTechvidvan Java Tutorial\u201d is considered as command-line arguments in the form of a String array.<\/p>\n
We need to pass the arguments as space-separated values. We can pass both strings and primitive data types(int, double, float, char, etc) as command-line arguments. These arguments convert into a string array and provided to the main() function as a string array argument.<\/p>\n
Internally, JVM wraps up these command-line arguments into the args[ ] array that we pass into the main() function. We can check these arguments using args.length method.<\/p>\n
JVM stores the first command-line argument at args[0], the second at args[1], third at args[2], and so on.<\/p>\n
Let\u2019s learn how to use command-line arguments in our Java program.<\/p>\n
Java code to understand the command-line arguments<\/h5>\n
To understand the command-line argument we will create a file named CommandLine.java and write the following code to display all the arguments that we will pass through the command-line:<\/p>\n
\/\/Display all command-line arguments.\nclass CommandLine\n{\n public static void main(String args[ ])\n {\n System.out.println(\u201cThe command-line arguments are:\\n\u201d);\n for (int x = 0; x < args.length; x++)\n System.out.println(\"args[\" + x + \"]: \" + args[ x ]);\n }\n}\n<\/pre>\nSteps to run the above program<\/strong><\/p>\nTo compile and run a java program in command prompt, follow the steps written below.<\/p>\n
\n- Save the program as CommandLine.java<\/li>\n
- Open the command prompt window and compile the program- javac CommandLine.java<\/li>\n
- After a successful compilation of the program, run the following command by writing the arguments- java CommandLine argument-list<\/li>\n
- For example – java CommandLine TechVidvan Java Tutorial<\/li>\n
- Press Enter and you will get the desired output.<\/li>\n<\/ul>\n
After performing the above steps, we will get the following output:<\/p>\n
Output:<\/strong><\/p>\n![\"Command](\"https:\/\/techvidvan.com\/tutorials\/wp-content\/uploads\/sites\/2\/2020\/04\/Screenshot-from-2020-03-11-15-53-36.png\")
<\/a><\/p>\nExample of command-line argument in java that prints only one argument<\/h4>\n
We can also display a single argument in the command prompt. Following code shows this example:<\/p>\n
\/\/Display one command-line argument.\nclass CommandLine\n{\n public static void main(String args[ ])\n {\n String name = args[3];\n System.out.println(\"The name of the user is: \" +name);\n }\n}\n<\/pre>\nOutput:<\/strong><\/p>\n![\"Command](\"https:\/\/techvidvan.com\/tutorials\/wp-content\/uploads\/sites\/2\/2020\/04\/Screenshot-from-2020-03-11-15-48-24.png\")
<\/a><\/p>\nHow to Pass Numeric Command-Line Arguments in Java?<\/h4>\n
The main() method of a Java program only accepts the data with the string type arguments. Therefore, we can never pass numeric arguments through the command line.<\/p>\n
If we pass them, they are converted int string and we can\u2019t use them as numbers and can\u2019t perform any numeric operations with them.<\/p>\n
But, we can convert these string(numeric) arguments into numeric values. Let\u2019s see an example to understand it.<\/p>\n
public class NumericArguments\n{\n public static void main(String[] args)\n {\n \/\/ convert into integer type\n int number1 = Integer.parseInt(args[0]);\n System.out.println(\"First Number: \" +number1);\n\n int number2 = Integer.parseInt(args[1]);\n System.out.println(\"Second Number: \" +number2);\n int result = number1 + number2;\n System.out.println(\"Addition of two numbers is: \" +result);\n }\n}\n<\/pre>\nOutput:<\/strong><\/p>\n![\"Passing](\"https:\/\/techvidvan.com\/tutorials\/wp-content\/uploads\/sites\/2\/2020\/04\/Screenshot-from-2020-03-11-16-14-47.png\")
<\/a><\/p>\nIn the above program, we used the parseInt() method of the Integer class to convert the string argument into an integer.<\/p>\n
Similarly, we can use the parseDouble() to convert the string into a double value and parseFloat() method to convert the string into a float value.<\/p>\n
How to Pass Command Line Arguments in Eclipse IDE<\/h4>\n
We can also pass command-line arguments in Eclipse IDE using Run Configurations.<\/p>\n
Step 1<\/h4>\n
Open the Java program in Eclipse<\/p>\n
![\"Open](\"https:\/\/techvidvan.com\/tutorials\/wp-content\/uploads\/sites\/2\/2020\/04\/Screenshot-from-2020-03-11-16-46-05.png\")
<\/a><\/p>\nStep 2<\/h4>\n
From the editor, right-click and choose “Run As” option. Inside it, select the “Run Configurations\u2026 option”. After choosing Run Configurations, you will see following screen:<\/p>\n
![\"Run](\"https:\/\/techvidvan.com\/tutorials\/wp-content\/uploads\/sites\/2\/2020\/04\/Screenshot-from-2020-03-11-16-49-50.png\")
<\/a><\/p>\nStep 3<\/h4>\n
In the pop-up window, click on the Arguments tab. Then provide the command line argument value in the “Program Arguments” text box.<\/p>\n
![\"Java](\"https:\/\/techvidvan.com\/tutorials\/wp-content\/uploads\/sites\/2\/2020\/04\/Screenshot-from-2020-03-11-16-51-18.png\")
<\/a><\/p>\nStep 4<\/h4>\n
Click on the Run button<\/p>\n
When you will click on the Run button, you will get the following output:<\/p>\n