如何从文件中读取数字并在 java 中对它们执行操作？

Question

this is my file information:

mahdi aspanani 664 22.0 ali moghadasi 675 26.0

I want to read this information from file and count 22.0 + 26.0

how can I do this in java?

Answer 1

1. First, open your file with a Scanner instance.
2. Read each line.
3. Split on spaces
4. Convert the fourth token to a double.
5. Add it to sum.
6. Continue until no more lines.

        Scanner input;
        String myFileName = "......";
        try {
            input = new Scanner(new File(myFileName)); 
            double sum = 0;
            while (input.hasNextLine()) {
                String line = input.nextLine();
                String[] vals = line.split("\\s+");
                sum += Double.parseDouble(vals[3]);
            }
            System.out.println("sum = " + sum);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

Answer 2

Assuming you mean the content of the file is structured like this:

<string> <string> <int> <summand 1> <string> <string> <int> <summand 2>

and none of the strings contains spaces and both summands are doubles, you can do the following:

try(BufferedReader br=new BufferedReader(new FileReader(filename))){
    String[] split=br.readLine().split(" ");
    double result=Double.parseDouble(split[3])+Double.parseDouble(split[7]);
    //do with it whatever you want
}catch(IOException e){
     e.printStackTrace();//or do something else or don't catch it and add it to the signature
}

Don't forget to put the name ofthe file instead of filename .