Echoing Command-Line Arguments
NON-NUMERIC
1.
class CommandLineExample{
2.
public static void main(String args[]){
3.
System.out.println("Your first argument is: "+args[0]);
4.
}
5.
}
1. compile by > javac CommandLineExample.java
2. run by > java CommandLineExample sonoo
Output: Your first argument is: sonoo
1. Public class A{
2. public static void main(String args[]){
3.
4. for(int i=0;i<args.length;i++)
5. System.out.println(args[i]);
6.
7. }
8. }
compile by > javac A.java
run by > java A bvcoe
NM 1 3 abc
Output: bvcoe
NM
1
3
abc
public class Echo {
public static void main (String[] args) {
for (String s: args) {
System.out.println(s);
}
}
}
The following example
shows how a user might run Echo. User input is in italics.
java Echo Drink Hot Java
Drink
Hot
Java
Note that the
application displays each word — Drink, Hot, and Java — on a line by itself. This is because the
space character separates command-line arguments. To have Drink, Hot, and Java interpreted as a
single argument, the user would join them by enclosing them within quotation
marks.
java Echo "Drink
Hot Java"
Drink Hot Java
Parsing Numeric Command-Line Arguments
If an application needs
to support a numeric command-line argument, it must convert a String argument
that represents a number, such as "34", to a numeric value. Here is a
code snippet that converts a command-line argument to an int:
int firstArg;
if (args.length > 0)
{
try {
firstArg = Integer.parseInt(args[0]);
} catch (NumberFormatException e) {
System.err.println("Argument"
+ args[0] + " must be an integer.");
System.exit(1);
}
}
parseInt throws a NumberFormatException if the format of args[0] isn't
valid. All of the Number classes — Integer, Float, Double,
and so on — have parseXXX methods that convert a String representing
a number to an object of their type.
