Access list from one method to another

In my method loadData() I read and store data from a textfile with the following structure:

1946-01-12;07:00:00;-1.3;G
1946-01-12;13:00:00;0.3;G
1946-01-12;18:00:00;-2.8;G
1946-01-13;07:00:00;-6.2;G
1946-01-13;13:00:00;-4.7;G
1946-01-13;18:00:00;-4.3;G

I store date, time and temperature in the variables dateTime, Time and temperature respectively. I wonder how I can access these variables, for example dateTime in another method public List<String> missingValues(LocalDate dateFrom, LocalDate dateTo) {}? I want to create a new list in this new method with same values as in dateTime like this: List<LocalDate> list2 = Arrays.asList(dateTime); Is it possible?

public class WeatherDataHandler {

  public WeatherDataHandler(LocalDate dateTime,LocalTime Time, double temperature, String tag) {
  }

  private static List<WeatherDataHandler> weatherData = new ArrayList<>();

  public void loadData(String filePath) throws IOException {
    //Read all data
	List<String> fileData = Files.readAllLines(Paths.get("filePath"));
	System.out.println(fileData);
	    for(String str : fileData) {
        List<String> parsed = parseData(str);
        LocalDate dateTime = LocalDate.parse(parsed.get(0));
        LocalTime Time = LocalTime.parse(parsed.get(1));
        double temperature = Double.parseDouble(parsed.get(2));
        String tag = parsed.get(3);

        WeatherDataHandler weather = new WeatherDataHandler(dateTime, Time, temperature, tag);
        weatherData.add(weather);
        System.out.println(dateTime);}
	}

  private static List<String> parseData(String s) {
    return Arrays.asList(s.split(";"));

  }

  public List<String> missingValues(LocalDate dateFrom, LocalDate dateTo) {

    return null;
  }
}

As you've saved values to a static field called weatherData, you can simply access them by referring to weatherData field directly.

You create a new WeatherDataHandler object. However, you don't save the values passed to the constructor in that object. You might find it easier if you create a separate class to hold details of the Weather.

e.g. Class to hold one row from the file:

public class Weather {

    private LocalDate dateTime;
    private LocalTime time;
    private double temperature;
    private String tag;

    public Weather(LocalDate dateTime, LocalTime time, double temperature, String tag) {
        this.dateTime = dateTime;
        this.time = time;
        this.temperature = temperature;
        this.tag = tag;
    }

    public LocalDate getDateTime() {
        return dateTime;
    }

    public void setDateTime(LocalDate dateTime) {
        this.dateTime = dateTime;
    }

    public LocalTime getTime() {
        return time;
    }

    public void setTime(LocalTime time) {
        this.time = time;
    }

    public double getTemperature() {
        return temperature;
    }

    public void setTemperature(double temperature) {
        this.temperature = temperature;
    }

    public String getTag() {
        return tag;
    }

    public void setTag(String tag) {
        this.tag = tag;
    }
}

And changes to the WeatherDataHandler to use the Weather class:

public class WeatherDataHandler {

    // You probably don't need this to be static
    private List<Weather> weatherData = new ArrayList<>();

    public void loadData(String filePath) throws IOException {
        //Read all data
        List<String> fileData = Files.readAllLines(Paths.get(filePath));
        System.out.println(fileData);
        for(String str : fileData) {
            List<String> parsed = parseData(str);
            LocalDate dateTime = LocalDate.parse(parsed.get(0));
            LocalTime Time = LocalTime.parse(parsed.get(1));
            double temperature = Double.parseDouble(parsed.get(2));
            String tag = parsed.get(3);

            Weather weather = new Weather(dateTime, Time, temperature, tag);
            weatherData.add(weather);
            System.out.println(dateTime);}
    }

    // You probably don't need this to be static
    private List<String> parseData(String s) {
        return Arrays.asList(s.split(";"));

    }

    public List<String> missingValues(LocalDate dateFrom, LocalDate dateTo) {
        // access the weatherData directly
        List<String> values = new ArrayList<>();
        for (Weather weather : weatherData) {
            values.add(weather.getDateTime().toString());
        }
        return values;
    }
}