Question

I recently start studying JAVA, and I find this code:

public class Dublicate{
   public static void main(String[] args){
      int r=0;
      for(int i=0;i<(args[0]).length();i++){
         char ch=args[0].CharAt(i);
         r=r*10+ch-'0';
      }
      System.out.println(r);
    }
} 

I don’t really confident that this code will work properly, I don’t confident in
args[0], but this code don’t what to compile:

Dublicate.java:6: cannot find symbol  
symbol  : method CharAt(int)  
location: class java.lang.String  
            char ch=a.CharAt(i);  
                     ^  
1 error

How I can solve this problem?

P.S. Also if I write:

int i=4;
String a = "argsas";
char ch=a.CharAt(i); 

I also get Error:

Dublicate.java:5: cannot find symbol  
symbol  : method CharAt(int)  
location: class java.lang.String  
             char ch=a.CharAt(i);  
                      ^  
1 error  

Update:
Yeah, lovercase works thank you all!!!

Answer 1

It’s “charAt” – lower case. .NET starts method with upper case as a convention; Java uses lower case. If you found this code somewhere, it’s a bad choice.

public class Dublicate{
    public static void main(String[] args){
        if (args.length > 0) {
           int r=0;
           for (int i = 0; i < args[0].length(); ++i) { 
                char ch=args[0].charAt(i);
                r=r*10+ch-'0';
            }
            System.out.println(r);
        }
    }
}