Question

I am having trouble making a StringTokenizer break up a few lines of text into separate tokens. The inputted text is

3
monkeys

But, the StringTokenizer is apparently interpreting this as “3monkeys”. I need it to be “3” and “monkeys”. Because of this, a NumberFormatException is being throw since I need to convert the string “3” into an integer.

This is the code I have so far.

    Scanner f = new Scanner( new FileInputStream("input.txt" )); // Yes, i have the actual input file path here, but I changed it for this question.
    PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("output.txt")));

    String temp = "";
    //String cString = "";

    while( f.hasNextLine() ) {
        String cString = f.nextLine();
        temp += cString;
    }
    StringTokenizer everythingTokens = new StringTokenizer( temp );
    String[] everything = new String[ everythingTokens.countTokens() ];

    for( int i = 0; i < everything.length; i++ ) {
        everything[ i ] = everythingTokens.nextToken();
    }

    int numberOfPeople = Integer.parseInt( everything[ 0 ] ); // Line where exception occurs.
    out.println( everything[ 0 ] );

The error message is this

Exception in thread "main" java.lang.NumberFormatException: For input string: "3monkeys"
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
at java.lang.Integer.parseInt(Integer.java:492)
at java.lang.Integer.parseInt(Integer.java:527)
at gift1.main(gift1.java:32)
Java Result: 1

Why is this happening and how can I fix it?

Answer 1

As you’re appending each line to a string via temp += cString, what you have is “3” + “monkeys”, which is “3monkeys”. You can solve this by adding a space after each line; temp += cString + " ".