想要从文本文件中随机选择单词，而不是从文本文件中打印所有内容

Question

I want the compiler to randomly choose a word from text instead of printing everything from a text file. Right now the code below is printing everything from the text file. I think there is something wrong with my getWord method because when I call the getWord method from the main function I get an error .

public class TextFile {

        protected static Scanner file;
        protected static List<String> words;


        public TextFile(){
            words = openFile();
        }

        private List<String> openFile() {

            //List<String> wordList = new ArrayList<String>();

                try {
                    file = new Scanner(new File("words.txt"));

                } catch (FileNotFoundException e) {
                    System.out.println("File Not Found");
                } catch (Exception e) {
                    System.out.println("IOEXCEPTION");
                }

                return words;
        }

        public void readFile() throws FileNotFoundException {

            //ArrayList<String> wordList = new ArrayList<String>();

            while(file.hasNext()){
                String a = file.nextLine();
                //Collections.shuffle(words);
                //String pickWord = words.get(1);
                //String[] a = 
                System.out.println(a);
            }
        }

        public void closeFile() {
            file.close();
        }

        public String getWord() {

            Random r = new Random(words.size());
            String randomWord = words.get(r.nextInt());
            //System.out.println(randomWord);

            return randomWord;
        }

        public static void main(String[] args) throws FileNotFoundException {

            try {

                TextFile file = new TextFile();

                file.openFile();
                file.readFile();

                file.closeFile();

            } catch (Exception e) {
                System.out.println("IOEXCEPTION");
            }
        }
    }

Answer 1

in the openfile method you are retuning a "word" variable which is null assign value to the variable

the error is coming from the {getword();} because you are accessing properties of a null variable its a error

     public List<String> readFile() throws FileNotFoundException {
       while(file.hasNext()){
            String a = file.nextLine();
            words.add(a);
            System.out.println(a);
        }
       return words;
    }

inside the open file method at the return statement line call "return readfile();" and try ur code\\

no need to call readfile method inside the main method

Answer 2

You are getting exception while calling getWord method as it throws IndexOutOfBoundsException at line String randomWord = words.get(r.nextInt()); .

PFB correction to getWord method:

public String getWord() {
    //You can use any approach..Random or Collections
    //Random r = new Random();      
    //String randomWord = words.get(r.nextInt(words.size()));

    Collections.shuffle(words);
    String randomWord = words.get(1);

    return randomWord;
}

Again you should populate words field correctly:

public void readFile() throws FileNotFoundException {

    words = new ArrayList<String>();

    while (file.hasNext())
        words.add(file.nextLine());
}

Answer 3

Try this. You don't need to use the getWord() method in the main. Also, create a constructor for the class:

public TextFile() {
}

Your openFile() method doesn't need to return string.

    private void openFile() {


          try {
                file = new Scanner(new File("words.txt"));

            } catch (FileNotFoundException e) {
                System.out.println("File Not Found");
            } catch (Exception e) {
                System.out.println("IOEXCEPTION");
            }
}

Here is your readFile() method: 1)Read file 2)Split a line of words into each word and put it in array 3)Then, random word

public void readFile() throws FileNotFoundException {

    //  List<String> wordList = new ArrayList<String>();


        while(file.hasNext()){


            String line = file.nextLine(); //read file one line at a time

            String[] parseWords = line.split(" "); //Parse what you read


            int index = new Random().nextInt(parseWords.length);

            String randW = parseWords[index];
            System.out.println(randW);

        }
    }

In your main method:

TextFile file1 = new TextFile ();

file1.openFile();
file1.readFile();
file1.closeFile();