java storing output from file into an array

问题

I have a question on how to store output from a file into an array. In my case, I am trying to store all the date in a file into an array. For the way that I did it, the compiler complains "not a statement". How can I fix this? Any help will be greatly appreciated. Below is my code (the line of error is preceded by backslashes):

double token[] = new double[9];

            File filename = new File("/Users/timothylee/gravity1.txt");

            Scanner inFile = new Scanner(filename);

            while(inFile.hasNext()){
               //////////////// token[] = inFile.nextDouble();
                System.out.println(token);
            }
            inFile.close();

If needed, here is the file:

gravity1.txt:
      3.70
      8.87
      9.79
      3.70
      24.78
      10.44
      8.86
      11.13
      0.61

回答1:

double token[] = new double[9];

int i = 0;
while(inFile.hasNext()){
    token[i] = inFile.nextDouble();
    System.out.println(token);
    i++;
}
inFile.close();

This is assuming the file only has 9 lines.

回答2:

        ArrayList<Double> token = new ArrayList<Double>();

        File filename = new File("/Users/timothylee/gravity1.txt");

        Scanner inFile = new Scanner(filename);

        while(inFile.hasNext()){
            token.add(inFile.nextDouble());
        }
        inFile.close();
        System.out.println(Arrays.toString(token));

Just use an ArrayList, dont make your life harder as it is. ;) This also makes it way more flexible, as it doesnt matter how many data/lines are in your file.

回答3:

You are not assigning anything to your token array, which is why you are getting the "not a statement" error. You need to tell Java where to put the next double like this:

double token[] = new double[9];
File filename = new File("/Users/timothylee/gravity1.txt");

        Scanner inFile = new Scanner(filename);
        int i = 0;
        while(inFile.hasNext()){
           token[i] = inFile.nextDouble();
            System.out.println(token);
           i++;
        }
        inFile.close();

回答4:

This would be simpler in Java 8 with map. Here is the Java 7 version:

    File filename = new File("/Users/timothylee/gravity1.txt");

    List<Double> doubleList = new ArrayList<Double>();
    try (BufferedReader reader = new BufferedReader(new FileReader(file))) {
        String line;
        while ((line = reader.readLine()) != null) {
            doubleList.add(Double.parseDouble(line))
        }
    }

    double[] doubles = new double[doubleList.size()];
    for (int i = 0; i < doubleList.size(); i++) {
        doubles[i] = doubleList.get(i);
    }

来源：https://stackoverflow.com/questions/20549272/java-storing-output-from-file-into-an-array