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Thread: reading string in from text file

  1. #1
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    Default reading string in from text file

    Hey Guys... im getting an error could you help?

     

    Exception in thread "main" java.lang.NumberFormatException: For input string: "bogus"
    at java.lang.NumberFormatException.forInputString(Num berFormatException.java:48)
    at java.lang.Integer.parseInt(Integer.java:449)
    at java.lang.Integer.parseInt(Integer.java:499)
    at lab10.main(lab10.java:47)




    Heres my .txt file
    100
    200
    bogus
    300
    150
    weasel
    400
    600
    250
    3.5
    800
    50
    500
    450
    600
    550


    import java.util.*;
    import java.io.*;
    public class lab10
    {
     
    	public static void main(String [] args)
    	{
    		Scanner inScan;
    		Scanner fScan = null;
    		inScan = new Scanner (System.in);
    		String nextItem;
    		int nextInt = 0;
    		int i = 0;
     
     
    		int [] A = new int [5];
     
    		boolean check = true; 
     
    	while (check = true){
    	      System.out.println("Please enter the file to read from: ");
    		  String fName = inScan.nextLine();
     
     
     
     
     
     
    		try {
     
     
    			fScan = new Scanner (new File(fName));
     
    			while (fScan.hasNextLine())
    			{
     
    				nextItem = fScan.nextLine(); // Stores first number into nextItem
     
     
    				// nextLine READS STRINGS
    	// something going on here.... ^ v reason for this
     
    				// TAKES String and makes it INT!  
    				nextInt = Integer.parseInt(nextItem);
     
     
     
     
     
     
    				A[i] = nextInt; // array 
     
     
     
     
     
    			    i++;  // increments the counter 
     
     
     
     
    			   // System.out.println( " is not an integer -- ignored");
     
                }
     
     
     
     
     
     
     
    			System.out.println("Here are your " + i + " items:");
    			for (int j = 0; j < i; j++)
    			{
    				System.out.println(A[j] + " ");
     
    			}
     
     
     
    		} catch (FileNotFoundException e) {
     
    			System.out.println("Your file is invalid ");
     
     
     
     
     
    		}
     
     
     
    	}// end while
     
     
    	}
     
    }


  2. #2
    Senile Half-Wit Freaky Chris's Avatar
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    Default Re: reading string in from text file

    You are trying to convert each line of the file into an integer,
    nextInt = Integer.parseInt(nextItem);

    So when you hit a text string containing non numeric characters you are going to have a problem. The method parseInt() throws an exception NumberFormatException when it tries to parse a string that contains non numeric data, you need to find a way of handling this. Either use a try/catch block to catch the exception and deal with it appropriately or parse the strings yousrself beforehand to check if they are inetegers or not.

    Integer (Java Platform SE 6)

    Chris
    chris[at]javaprogrammingforums[dot]com

    Prifysgol Bangor University, North Wales

  3. #3
    mmm.. coffee JavaPF's Avatar
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    Default Re: reading string in from text file

    Hello basketball8533.

    Welcome to the Java Programming Forums.

    The clue is in the exception. java.lang.NumberFormatException: For input string: "bogus"

    The String "bogus" in the txt file is causing the issue because you are adding the values to an integer array.
    You cannot add Strings to an integer array.

    I notice there is also a double value in the txt file.
    Please use [highlight=Java] code [/highlight] tags when posting your code.
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    mmm.. coffee JavaPF's Avatar
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    Default Re: reading string in from text file

    Quote Originally Posted by Freaky Chris View Post
    You are trying to convert each line of the file into an integer,
    nextInt = Integer.parseInt(nextItem);

    So when you hit a text string containing non numeric characters you are going to have a problem. The method parseInt() throws an exception NumberFormatException when it tries to parse a string that contains non numeric data, you need to find a way of handling this. Either use a try/catch block to catch the exception and deal with it appropriately or parse the strings yousrself beforehand to check if they are inetegers or not.

    Integer (Java Platform SE 6)

    Chris
    Ah you just beat me to it!
    Please use [highlight=Java] code [/highlight] tags when posting your code.
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  5. #5
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    Default Re: reading string in from text file

    nextItem = fScan.nextLine(); // Stores first number into nextItem


    // nextLine READS STRINGS
    // something going on here.... ^ v reason for this

    // TAKES String and makes it INT!
    nextInt = Integer.parseInt(nextItem);

    You could just have

    int x = fScan.nextInt();

    However, bogus is a String.

    How can you turn it into an int?

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