About the error control

Question

public static void main(String[] args) {
          if(args.length == 0) {
               System.out.println("Usage: java ChargenClient host [port]");
               return;
Above is a prt of my nio program at client side...
while i try to connect to server side, it keep failed and showing the msg of Usage: java ChargenClient host [port]..
i would like to know what the means by the control method of
if(args.length == 0)...
and what to do to avoid the args.length keep equal to 0??
i am quite new in java...so please somebody help me out.

Answer 1

public static void main(String[] args) {
          if(args.length == 0) {
System.out.println("Usage: java ChargenClient host
ost [port]");
               return;
Above is a prt of my nio program at client side...
while i try to connect to server side, it keep failed
and showing the msg of Usage: java ChargenClient host
[port]..
i would like to know what the means by the control
method of
if(args.length == 0)...
and what to do to avoid the args.length keep equal to
0??
args is an array of Strings that hold the command line arguments which get passed by the one who's running the application.
Compile the following code:public class Main {  
    public static void main(String[] args) {
        System.out.println("You provided "+args.length+" arguments.");
        for(int i = 0; i < args.length; i++) {
            System.out.println((i+1)+" = "+args);
Now run it from the command prompt like this:java -cp . Main some command line arguments ...