如何从 ArrayList 中获取重复值? [英] How can I get duplicated values from ArrayList?

问题描述

这是我的代码:

import java.io.File;导入 java.io.FileNotFoundException;导入 java.io.PrintWriter;导入 java.util.ArrayList;导入 java.util.Collections;导入 java.util.Iterator;公共类比较文件 {比较文件(){}布尔检查 = 假；整数计数 = 0;/** 此方法返回一个文件类型变量* 变量路径 - 此参数采用指定根目录中的路径* 它也是一个私有方法，应该在类对象的帮助下调用他*/公共文件查找(文件路径)抛出 FileNotFoundException {PrintWriter writer = new PrintWriter("D:/Photos/name.txt");ArrayList缓冲区 = 新的 ArrayList();/** 让我们创建文件数组* 必须在哪里找到所有文件* 我们使用 File[]，并命名为 'files'* 变量文件采用找到的文件列表* 在 listFiles 方法的帮助下，* 返回文件和目录列表*/File[] 文件 = path.listFiles();//System.out.println(files.toString());尝试 {/** 我们应该使用 for each 循环* 在这个循环中，我们将创建文件类型变量 'file'* 然后我们将对变量文件中的每个表达式进行迭代*/对于(文件文件:文件){//打印所有找到的文件和目录//如果文件或目录存在如果(文件.isDirectory()){//递归返回文件和目录查找(文件)；}别的 {buffer.add(file.getName());System.out.println(文件);}}}捕获(异常 e){System.out.print("错误");}最后{如果(作家！= null)writer.close();}/*迭代器<字符串>i = buffer.iterator();while(i.hasNext()) {System.out.println(i.next());}*/返回路径；}public static void main(String[] args) 抛出 FileNotFoundException {File mainFile = new File("D:/Photos/");CompareFile main = new CompareFile();main.find(mainFile);}}

如果我使用排序，排序后，结果不好，因为来自目录照片"的第一行，和目录Photos/sub"中目录的第二行让我们看看屏幕:我想你明白)

http://s10.postimg.org/7hcw83z9x/image.png

解决方案

您需要跟踪您在树中的位置，将 find 方法更改为采用路径:

public File find(File path, string path="") 抛出 FileNotFoundException

递归调用find方法时:find(file, path + file.getName() + "/")

然后当你添加到列表中时，使用buffer.add(path + file.getName());

There is my code:

import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;


public class CompareFile {

    CompareFile() {}

    boolean check = false;
    int count = 0;

    /*
     * this method return a File type variable
     * variable path - this parameter takes a path in specified root
     * also it's a private method and he should be called with help by class object
     */
    public File find(File path) throws FileNotFoundException {
        PrintWriter writer = new PrintWriter("D:/Photos/name.txt");

        ArrayList<String> buffer = new ArrayList<String>();

        /*
         * let's create array of files
         * where must be all found files
         * We use File[], and named 'files'
         * variable files takes on list of found files
         * with help by listFiles method, that
         * return list of files and directories
         */
        File[] files = path.listFiles();
        //System.out.println(files.toString());

        try {       
            /*
             * we'll ought use the for each loop
             * in this loop we'll create File type variable 'file'
             * then we'll do iterating for each expression from variable files
             */
            for (File file : files) {
                //print all found files and directories

               //if file or directory exists
                if (file.isDirectory()) {

                    //recursively return file and directory
                    find(file);
                } 
                else {
                        buffer.add(file.getName());
                            System.out.println(file);
                }
            }
        }
        catch (Exception e)  {
            System.out.print("Error");
        }
        finally{
            if ( writer != null ) 
                writer.close();
        }


       /*
            Iterator<String> i = buffer.iterator();
                while(i.hasNext()) {
                    System.out.println(i.next());
                }*/

        return path;
    }

    public static void main(String[] args) throws FileNotFoundException  {
        File mainFile = new File("D:/Photos/");

        CompareFile main = new CompareFile();
        main.find(mainFile);
    }
}

If I use sort, after sorting, the result bad, because first row from dir "Photos", and second row from directory in directory "Photos/sub" Let's look at the screen: I think you understand)

http://s10.postimg.org/7hcw83z9x/image.png

解决方案

You'll need to keep track of where you are in the tree, change the find method to take a path:

public File find(File path, string path="") throws FileNotFoundException

When you call the find method recursively: find(file, path + file.getName() + "/")

Then when you add to the list, use buffer.add(path + file.getName());

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