Java command line arguments example

Java command line arguments example

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Java command line arguments parser

Here is an example of a simple Java program that parses command-line arguments:

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Arrays;
public class CommandLineArgsParser {
public static void main(String[] args) {
// Get the class loader for this class
ClassLoader cl = getClass().getClassLoader();
// Get the method that handles command-line arguments
Method parseMethod = getMethod(cl, "parseArguments", String[].class);
if (parseMethod != null) {
try {
// Call the parseMethod with the command-line arguments
Object result = parseMethod.invoke(null, args);
// Print the result
System.out.println(result);
} catch (IllegalAccessException e) {
System.err.println("Error: " + e.getMessage());
} catch (InvocationTargetException e) {
System.err.println("Error: " + e.getTargetException().getMessage());
}
} else {
System.out.println("No parse method found!");
}
}
private static ClassLoader getClass() {
return CommandLineArgsParser.class.getClassLoader();
}
private static Method getMethod(ClassLoader cl, String name, Class<?>[] parameterTypes) {
try {
// Get the class that contains the method
Class<?> clazz = cl.loadClass("CommandLineArgsParser");
// Get the method using reflection
return clazz.getMethod(name, parameterTypes);
} catch (ClassNotFoundException e) {
System.err.println("Error: " + e.getMessage());
return null;
} catch (NoSuchMethodException e) {
System.err.println("Error: No such method found!");
return null;
}
}
public static Object parseArguments(String[] args) {
// Parse the command-line arguments here
for (String arg : args) {
System.out.println("Argument: " + arg);
}
return null; // Return some value or result
}
}

This program uses reflection to dynamically determine which method to call based on the class loader. The parseArguments method is responsible for parsing the command-line arguments. In this example, it simply prints each argument.

Here's how you can use this class:

   javac CommandLineArgsParser.java

   java CommandLineArgsParser one two three four

When you run this program, it will print each command-line argument:

Argument: one
Argument: two
Argument: three
Argument: four
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