从文件中添加一行数字，并将平均值存储到双向量中

Question

我需要使用双向量来存储学生的平均值。

正在读取的文件设置如下:

2  //num of students
60   //total possible score
John   //name
4 16 9 7 10  //scores

所以我需要将字符串转换为双精度类型，将该行的所有整型加起来，除以平均值，然后将平均值存储到双精度向量中。

到目前为止，我的代码是:

public static String line;
public static Scanner in = new Scanner(System.in);
public static void main(String[] args) {

    System.out.println("enter the name of your file");
    String filename = in.next();
    FileIn file = new FileIn(filename);
    String firstLine; // String to hold first line which is number of students total in file.
    String secondLine; //String to hold second line which is number of points available 

    ArrayList<String> students = new ArrayList<String>();  // holds the students names
    //reads first line of the file. sets that number as the number of students
    firstLine = file.read();
    int numStu = Integer.parseInt(firstLine);
    // Just to test that number is being read correctly.
    System.out.println(numStu + " Number of students");
    //reads the second line of the file. sets that number as the total possible points in a semester
    secondLine = file.read();
    int totalPoints = Integer.parseInt(secondLine);
    // Just to test that number is being read correctly.
    System.out.println(totalPoints + " Total possible points");

    double avg = 0;
    double[]vector = new double [numStu]; 
    readFile(students,numStu,file,vector, avg);
    System.out.println(students);
    System.out.println(vector);
}
//puts the names into an arraylist and scores into a double vector
public static void readFile(ArrayList<String> students,int numStu, FileIn file, double[]vector, double avg)
{
    for(int k=0; k<(numStu*2); k++)
    {
                    //odd numbers are the students
        if (k % 2 == 0)
            students.add(file.read());
        else
        {
            //code to read and add the numbers from one line together, and storing the added and averaged score
        }
    }
}

}

正如你所看到的，我错过了底部的部分，我将文件元素分配到双向量

我的FileIn类是这样的:

private String myFileName;
private BufferedReader myFile;
public FileIn(String filename)
{
    myFileName = filename;
    try
    {
        myFile = new BufferedReader(new FileReader(myFileName));
    }
    catch(Exception e)
    {
        e.printStackTrace();
    }
    finally{}
}
public String read()
{
    String myLine = new String();
    try
    {
        myLine = myFile.readLine();
    }
    catch(Exception e)
    {
        e.printStackTrace();
    }
    finally{}
    return myLine;
}

}

Answer 1

First!请阅读我在你的问题下的评论。学习如何用更聪明的方式提出要求，学习如何分而治之。

这不是对你问题的直接回答，因为我认为程序员应该能够自己解决它，并学会在你的问题中使用它。

完成下面这段代码，一旦你完成它，你就会知道你自己问题的答案了。

public class Foo {
  public static int main(String[] args) {
    String input = "10 15 20.5 70 40";
    // write code to convert the input string to doubles and sum them up
    double sum = ......;
    // answer should equals to 155.5
  }
}

提示:String.split()和Double.parseDouble()，并使用for循环