将元素存储在文本文件中并调用信息

Question

I'm creating a program that basically has information about elements (From the periodic table) such as the atomic mass, number and symbol. I want to store all the information about them in a text file, but am unsure of how to code it to call upon the information separately (And not just read the text file line by line).

This is the code I'm using for each element so far:

private Element(int atomicNumber, double atomicMass, String atomicSymbol, String atomicName) {
    this.atomicNumber = atomicNumber;
    this.atomicMass = atomicMass;
    this.atomicSymbol = atomicSymbol;
    this.atomicName = atomicName;
}

In the same file, I was creating an element like this:

Element H = new Element(1, 1.008, "H", "Hydrogen");

How could I, instead of having all 118 elements in the same file as the code, put them in a text file and read them from there?

I'm using methods such as getAtomicNumber() and getAtomicMass(), etc to call upon the information.

Thanks.

Answer 1

You have multiple choices, since you can add any structure in a text file. My recomendation would be XML or CSV format. A CSV is more easy to manage/edit, but the XML is more structured and read friendly. I'm go with a simple CSV.

Put in your file a line for each Element (that will be readed into your Element class), and each Element attribute (number, mass, symbol and name) separated by comma in a specific order, something like this:

1,1.008,H,Hydrogen
2,5.021,C,Carbon
etc..

Then, your code should read the file, line by line, create instances of your element class and maybe save it in a list. Something like this:

Your Element Class

public class Element {

    private int atomicNumber;
    private double atomicMass;
    private String atomicSymbol;
    private String atomicName;

    public Element(int atomicNumber, double atomicMass, String atomicSymbol, String atomicName) {
        this.atomicNumber = atomicNumber;
        this.atomicMass = atomicMass;
        this.atomicSymbol = atomicSymbol;
        this.atomicName = atomicName;
    }

    public double getAtomicMass() {
        return atomicMass;
    }

    public void setAtomicMass(double atomicMass) {
        this.atomicMass = atomicMass;
    }

    public String getAtomicSymbol() {
        return atomicSymbol;
    }

    public void setAtomicSymbol(String atomicSymbol) {
        this.atomicSymbol = atomicSymbol;
    }

    public String getAtomicName() {
        return atomicName;
    }

    public void setAtomicName(String atomicName) {
        this.atomicName = atomicName;
    }

    public int getAtomicNumber() {
        return atomicNumber;
    }

    public void setAtomicNumber(int atomicNumber) {
        this.atomicNumber = atomicNumber;
    }

    @Override
    public String toString() {
        return "atomicMass: " + atomicMass
            + " | atomicSymbol: " + atomicSymbol
            + " | atomicName: " + atomicName
            + " | atomicNumber: " + atomicNumber;
    }
}

Elements file reader

public class ElementsFileReader {

    public static List<Element> read(String filePath) throws IOException {
        FileReader fileReader = new FileReader(new File(filePath));

        BufferedReader br = new BufferedReader(fileReader);

        List<Element> elements = new ArrayList<>();
        String line = null;
        while ((line = br.readLine()) != null) {
            String[] lineParts = line.split(",");
            int atomicNumber = Integer.parseInt(lineParts[0]);
            double atomicMass = Double.parseDouble(lineParts[1]);
            String atomicSymbol = lineParts[2];
            String atomicName = lineParts[3];

            elements.add(new Element(atomicNumber, atomicMass, atomicSymbol, atomicName));
        }
        return elements;
    }
}

Your main application using ElementsFileReader and Element

public static void main(String[] args){
    String filePath = "the path to your text file";

    List<Element> elements;
    try {
        elements = ElementsFileReader.read(filePath);
    } catch(IOException e){
        System.err.println("Something gone wrong reading elements file...");
        e.printStackTrace();
        return;
    }

    for(Element element : elements){
        System.out.println(element);
        // do your stuff
    }
}

Careful with the parseInt and parseDouble method, I'm assuming the right format in your text file. Hope this can help you.

Answer 2

Write all the elements to a file in the same format (1,1.008,H,Hydrogen), read line by line and create a Pojo object for each line and write it to Map.

public Map readFile(String filePath) {
    Map<Integer, Element> elementsMap = new HashMap<>();
    Scanner s;
    try {
        s = new Scanner(new File(filePath));
        while (s.hasNextLine()){
            String[] properties = s.nextLine().split(",");
            Element element = new Element();
            element.setAtomicNumber(Integer.parseInt(properties[0]));
            element.setAtomicMass(Double.parseDouble(properties[1]));
            element.setAtomicSymbol(properties[2]);
            element.setAtomicName(properties[3]);

            elementsMap.put(element.getAtomicNumber(), element);
        }
        s.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    }   

    return elementsMap;
}

You can have the Map key as any other unique element property according to your convenience.