从另一个类访问数组列表元素

Question

I have a main class which has an ArrayList . This ArrayList has a set of values stored via iteration. I need to use this ArrayList (fileList & directoryList) value in another class. How can I achieve this? I do not want to move the ArrayList into another class.

package com.filehandler;

import java.io.File;
import java.util.ArrayList;
import java.util.List;

public class FileFinder {

    public static void main(String[] args) {
        // TODO Auto-generated method stub


        int directoryCount = 0;

        /* Declare Lists for Files & Directories */
        List<String> fileList = new ArrayList<String>();
        List<String> directoryList = new ArrayList<String>();

        // enter code here

        /* Set file location */

        File myFolder = new File("O:\\The Ultimate Book Shelf\\Technical");
        File[] myFileList = myFolder.listFiles();

        /* Iterate the folder to get the details of Files & Folders */

        for (int count = 0; count < myFileList.length; count++) {
            if (myFileList[count].isFile()) {
                // System.out.println("File " + myFileList[count].getName());
                fileList.add(myFileList[count].getName());

            } else if (myFileList[count].isDirectory()) {
                directoryCount++;
                // System.out.println("Directory " +
                // myFileList[count].getName());
                directoryList.add(myFileList[count].getName());
            } else {
                System.out
                        .println("There are no files or directories in the mentioned path. Please verify the folder location.");
            }
        }
        System.out.println("Total Files : "
                + (myFileList.length - directoryCount));
        System.out.println("Total Directories :" + directoryCount);
        System.out.println(fileList);
        System.out.println(directoryList);

    }    
}

Answer 1

Your other class can either accept two ArrayLists in its own constructor or as parameters for a specific method, depending on what you are trying to do. By passing them as parameters you will actually pass a reference to the ArrayLists you created in you main function, therefore the other class will be able to read the values inside.

Answer 2

It depends how would the array be used in the second class. You have the following options.

1. To use the array in a method in the second class.
2. To use the array as a member in the second class.
3. To use the array as a static member in the second class.

For 1, you can simply pass the array to the method. For 2, you can pass the array to a constructor and initialize the member variables in the class. For 3, you can set like SecondClass.fileList = myFileList;