java - 显示列表数组中的文件名差异 (Java)

Question

我正在尝试比较文件，我的解决方案适用于其中包含少量文件(例如 10 个)的文件夹，但不适用于包含超过 200 个文件名的文件夹。我的代码的最后一部分返回 NULL 或 Results = [ ] 通常文本文件名称位于此处，显示两个文件夹之间的差异，感谢任何帮助。问题出在我的代码的最后一部分

package nameCompare;

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


// https://stackoverflow.com/questions/19662384/comparing-file-names
// http://www.javaprogrammingforums.com/java-programming-tutorials/3-java-program-can-list-all-files-given-directory.html

public class fileNameCompare {

    public static void main(String[] args) {
                             // first directory path here
        String path1 = "C:/Users/Jonathan/Desktop/ADP/MagMediaAfter";
        //String path1 = "C:/Users/Jonathan/Desktop/FolderA";

        // second directory path here
        String path2 = "C:/Users/Jonathan/Desktop/ADP/MagMediaAfter";
        //String path2 = "C:/Users/Jonathan/Desktop/FolderB";


        File folder1 = new File(path1);
        int fileCount = folder1.list().length;

        File folder2 = new File(path2);
        int fileCountTwo = folder2.list().length;


        File[] listOfFiles1 = folder1.listFiles();
        File[] listOfFiles2 = folder2.listFiles();

        //we'll need these to store the file names as Strings
        ArrayList<String> BeforeMM = new ArrayList<String>();
        ArrayList<String> AfterMM = new ArrayList<String>();

        //get file names from directory
        for (int i = 0; i < listOfFiles1.length; i++)
        {
            if (listOfFiles1[i].isFile())
            {
                BeforeMM.add(listOfFiles1[i].getName());//wow
            }
        }

        for (int i = 0; i < listOfFiles2.length; i++)
        {
            if (listOfFiles2[i].isFile())
            {
                AfterMM.add(listOfFiles2[i].getName());//seriously wow
            }
        }

            // Number of Files in each Folder or Directory
            System.out.println("Files in FolderA / BeforeMM ----> " + fileCount );
            System.out.println("Files in FolderB / AfterMM -----> " + fileCountTwo );
            System.out.println("------------------------------------");

            System.out.println( "Size/Number of Array Elements BeforeMM -----> "+BeforeMM.size() );
            System.out.println( "Size/Number of Array Elements AfterMM  -----> "+AfterMM.size() );
            System.out.println("------------------------------------");

            System.out.println("Before Media Folder Conatins----> " + BeforeMM );
            System.out.println("After Media Folder  Conatins----> " + AfterMM );
            System.out.println("------------------------------------");
            //this is where problems start
            List<String> result = AfterMM.stream().filter(elem -> !BeforeMM.contains(elem)).collect(Collectors.toList());
            System.out.println("Result: File(s) present in After BUT NOT BeforeMM folder:\n" + result);
            // Result equals Test2.txt

            /*// Remove all elements in BeforeFolder from AfterFolder
            BeforeMM.removeAll(AfterMM); 
            // Show results
            System.out.println("Result: " + AfterMM);
            */




    }




}

Answer 1

我们可以对您的代码进行许多改进和简化，首先您可以使用 System.getProperty("user.home") 构建您的路径。和 File(String, String) 构造函数。接下来，您可以使用流收集文件列表。然后你可以使用removeAll构建您的最终版List 。就像，

File desktop = new File(System.getProperty("user.home"), "Desktop");
File adp = new File(desktop, "ADP");
File folder1 = new File(adp, "MagMediaBefore");
File folder2 = new File(adp, "MagMediaAfter");
List<String> beforeMM = Stream.of(folder1.listFiles()) //
        .filter(File::isFile).map(File::getName) //
        .collect(Collectors.toList());
List<String> afterMM = Stream.of(folder2.listFiles()) //
        .filter(File::isFile).map(File::getName) //
        .collect(Collectors.toList());

// Number of Files in each Folder or Directory
System.out.println("Files in FolderA / BeforeMM ----> " //
        + beforeMM.size());
System.out.println("Files in FolderB / AfterMM -----> " //
        + afterMM.size());
System.out.println("------------------------------------");

System.out.println("Before Media Folder Conatins----> " //
        + beforeMM);
System.out.println("After Media Folder  Conatins----> " //
        + afterMM);
System.out.println("------------------------------------");
List<String> result = new ArrayList<>(afterMM);
result.removeAll(beforeMM);
System.out.println("Result: File(s) present in After BUT NOT " //
        + "BeforeMM folder: " + result);

请注意，您当前正在阅读 folder1 中的同一文件夹 和 folder2 。另外，请遵循 Java 变量命名约定( beforeMM 和 afterMM ，你的看起来像类名)。