StringIndexOutOfBounceException

Code :

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public class Sample {
 
    private static Scanner sc = new Scanner(System.in);
 
    public static void main(String[] args) {       
 
        String str;
 
        System.out.print("Enter: ");
        str = sc.nextLine();
 
        int x = 0;
 
        if ((str == null) || (str.equals("") || (str.equals(" ")))) {
 
            System.out.println("Invalid");
        }
 
        int sz = str.length();
 
        for (int i = 0; i < sz; i++) {
 
            x = i;
        }
 
        if (Character.isDigit(str.charAt(x)) == false) {
 
            System.out.println("Its Not A Number.");
        }
        else if (Character.isDigit(str.charAt(x)) == true) {
 
            System.out.println("Its A Number.");
        }  
    }
}

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this program is for checking if the input string or char is a number or not..

what i want is if the enterd value is " "(which is whitespace) and "" (which is empty) the program wont respond a StringOfIndexOutOfBounce... the compiler is pointing to this part

Code :

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   if (Character.isDigit(str.charAt(x)) == false) {

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i dont know how to get out of this mess..
please correct my mistakes coz i've only done this program a while ago which was sir Json gave me , and i applied the simple logic ofthis in one of my programs.

What input string do you use when you get this exception?

// Json

... If you want to check for a negative number, just use parseInt(), and catch the exception.

Code :

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     try
     {
          if (Integer.parseInt(someStr) < 0)
          {
               System.out.println("Negative number!");
          }
          else
          {
               System.out.println("Positive number!");
          }
     }
     Catch(Exception e)
     {
          System.out.println("You didn't enter a number :(");
     }

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Thats not good practise though, exceptions are sloooow :(

// Json

check your code, the maximum value for charAt() is str.length()-1, your x value is str.length()

:P The performance difference here is negligible. However, yes. Exceptions are generally bad practice (like goto's, though exceptions are slightly more useful and not quite as bad programming practice).

Quote:

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Thats not good practise though, exceptions are sloooow

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whaa!!! getting confuse here... exceptions are what? bad practice? so my my logic is right? i want to remove the exception by adjusting the logic of that code?

Quote:

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What input string do you use when you get this exception?

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i just want to input a white space or a blank String

Code :

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" "

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or

Code :

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""

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i want to remove that exception






and chris.. yes i adjusted the length of the string as you have taught me about String measurement (length()) but nothing happens... i tried to minus 1 the length.. it still outofbounds....




please help...



this is as simple as this...

1.) if the input string is null.. then i will make an output

Code :

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ERROR

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2.) if the input string is whitespace (" ") even greater than 1 whitespace (" ") then the output must be

Code :

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 EMPTY STRING. [ERROR]

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3.) last and for most, i want to remove that exception..


something a bit hard is poping in my mind.. do i have to catch that exception?

guys i've already solved a frament of my problem.

regarding with whitespaces (blank spaces) ,,

the only thing is the

Code :

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""

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empty string... its not null right? because im declaring double qoute
meaning that theres an empty string.. but i dont know how to get that index(i tried length() - 1)

still out of bounds...

and still the same.. want to remove that exception

Code :

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StringIndexOutOfBounds

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