Throw Exception in this code

in the following code converts Binary String into Decimal number
i want to throw NumberFormatException if the string isnt binary
how can i do that ?

Code:

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public class Exercise8_8 {
  public static void main(String[] args) {
    // Prompt the user to enter a string
    java.util.Scanner input = new java.util.Scanner(System.in);
    System.out.print("Enter a binary number string: ");
    String s = input.nextLine();
    System.out.println("The decimal value is " + parseBinary(s));
  }

  public static int parseBinary(String binaryString) {
    int value = binaryString.charAt(0) - '0';
    for (int i = 1; i < binaryString.length(); i++) {
      value = value * 2 + binaryString.charAt(i) - '0';
    }

    return value;
  }
}

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Thanks...

You can use Try Catch

yes i know
how can i do that?
thanks for reply.

You can find out how to do this from the tutorials. Please have a look here: Exceptions Tutorial

thanks all for reply
i under stand the concept but i steal cant use it
and this code is home work
so i want to do it before tomorrow
thanks again

Quote:

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Originally Posted by eng_hyzoom

thanks all for reply
i under stand the concept but i steal cant use it
and this code is home work
so i want to do it before tomorrow
thanks again

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If you detect a situation where you want to throw that exception, simply throw it:

Code:

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throw new NumberFormatException("you goofed!");

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... and let anything else catch it and do with it what it wants.

kind regards,

Jos

thanks very much Jos
this method parseBinary

Code:

---

public static int parseBinary(String binaryString) {
    int value = binaryString.charAt(0) - '0';
    for (int i = 1; i < binaryString.length(); i++) {
      value = value * 2 + binaryString.charAt(i) - '0';
    }

---

it used to convert binary String into binary
i want to put exception if user enter String not binary String
i dont know where i put this exception i tried put it was error
this is my trial there are 5 errors

Code:

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public static int parseBinary(String binaryString) {
          try{
                  int value = binaryString.charAt(0) - '0';
                      for (int i = 1; i < binaryString.length(); i++) {
      value = value * 2 + binaryString.charAt(i) - '0';
          }
            catch(Exception ex){
                  System.out.println("Exception");
          }
    }
    return value;
  }

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Can you please use code tags nest time.

What you mean by there are 5 errors?

What you have to do is, if you comes with an error return a value that you can handle in the invoked method, main in your case.

Quote:

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Originally Posted by eng_hyzoom

thanks very much Jos
this method parseBinary

Code:

---

public static int parseBinary(String binaryString) {
    int value = binaryString.charAt(0) - '0';
    for (int i = 1; i < binaryString.length(); i++) {
      value = value * 2 + binaryString.charAt(i) - '0';
    }

---

it used to convert binary String into binary
i want to put exception if user enter String not binary String

---

Your value 'binaryString.charAt(i) - '0'' needs to be a value 0 or 1; if it isn't simply throw that exception just as I showed you in my previous reply:

Code:

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int v= binaryString.charAt(i) - '0';
if (v < 0 || v > 1)
  throw new NumberFormatException("you goofed!");

---

kind regards,

Jos