java - 如何从另一个类的方法中获取变量值

Question

我有一个名为 ReadFile 的类，它有一个 ReadFile 函数，然后调用另外两个返回元素和数字的方法。如何从 ReadFile 类获取这些值以便传递给主类中的方法？

public static void main(String[] args)  {

        List<Integer> numbers = new ArrayList<>();
        List<Integer> elements = new ArrayList<>();

        ReadFile numbersFile = new ReadFile();
        numbersFile.readFile();

        preSortedList(numbers, elements);

        System.out.println();
        sortedList(numbers, elements);

} 


public class ReadFile {


   public void readFile(){

        File folder = new File("/Users/Mary/NetBeansProjects/Testing/src/program/pkg4/Input");

        for (File file : folder.listFiles()) {
            try{
                FileReader fileReader = new FileReader(file);
                BufferedReader reader = new BufferedReader(fileReader);

                List<Integer> elements = getElements(reader);
                List<Integer> numbers = getNumbers(reader, elements);

                reader.close(); 
            }catch(IOException e){
                System.out.println("ERROR: There was a problem reading the file.\n" + e.getMessage());
            }  
        }
    }      

    public static List<Integer> getElements(BufferedReader reader) throws IOException{
        List<Integer> elements = new ArrayList<>();
        String numberOfElement = reader.readLine();
        elements.add(Integer.parseInt(numberOfElement));
        return elements;
    }

    public static List<Integer> getNumbers(BufferedReader reader, List elements) throws IOException{
        List<Integer> numbers = new ArrayList<>();
        String line = reader.readLine();                  
        for (String s : line.split("\\s+")) {                        
            numbers.add(Integer.parseInt(s));
        }    
        return numbers;
    } 
}

Answer 1

在你的ReadFile类中创建两个成员变量name elements和numbers，然后在你的main方法中创建ReadFile类的对象并使用getter获取其成员的值。

public class ReadFile {
    List<Integer> elements
    List<Integer> numbers

      //Constructors

     //create getter and setters here


    public void readFile(){

    File folder = new File("/Users/Mary/NetBeansProjects/Testing/src/program/pkg4/Input");

    for (File file : folder.listFiles()) {
        try{
            FileReader fileReader = new FileReader(file);
            BufferedReader reader = new BufferedReader(fileReader);

            elements = getElements(reader);
            numbers = getNumbers(reader, elements);

            reader.close(); 
        }catch(IOException e){
            System.out.println("ERROR: There was a problem reading the file.\n" + e.getMessage());
        }  
    }
}      

public static List<Integer> getElements(BufferedReader reader) throws IOException{
    List<Integer> elements = new ArrayList<>();
    String numberOfElement = reader.readLine();
    elements.add(Integer.parseInt(numberOfElement));
    return elements;
}

public static List<Integer> getNumbers(BufferedReader reader, List elements) throws IOException{
    List<Integer> numbers = new ArrayList<>();
    String line = reader.readLine();                  
    for (String s : line.split("\\s+")) {                        
        numbers.add(Integer.parseInt(s));
    }    
    return numbers;
} 

}

然后在你的主要方法中

public static void main(String[] args)  {

    ReadFile numbersFile = new ReadFile();
    numbersFile.readFile();

    preSortedList(numbersFile.getNumbers(), numbersFile.getElements);

    System.out.println();
    sortedList(numbersFile.getNumbers(), numbersFile.getElements);

}