java—将switch方法应用于删除手机内存中文件的listview

bttbmeg0 于 2021-07-09 发布在 Java

关注(0)|答案(2)|浏览(270)

我有一个listview，它显示存储在手机内部存储器中的文件列表（不带文件扩展名）。那我就要实施 OnItemLongClickListener 允许用户删除文件。 OnItemLongClickListener 使用“switch”语句。
因为每次删除一个文件时，列表视图中项目的位置都会改变，所以我想实现一个规则，检查文件名是否与相关文件匹配，无论在案例0、案例1等中是否移动文件名。
需要说明的是：
初始列表视图：

switch          Listview items         related file to delete
    case 0;               A                          A.map
    case 1;               B                          B.map
    case 2;               C                          C.map
    case 3;               D                          D.map

删除b后的listview：

switch          Listview items         related file to delete
    case 0;               A                          A.map
    case 1;               C                          C.map
    case 2;               D

现在，如果之前我在案例1中写了一个删除b.map的规则，它可以正常工作。但现在c项的规则与案例1相同，规则不匹配。
因为我是android新手，我不知道如何解决这个问题。
有人能帮我吗？
这就是活动

public class MainActivity extends Activity {

ListView lv;
ArrayAdapter<String> adapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    lv = (ListView) findViewById(R.id.listView1);

    File dir = new File(Environment.getExternalStorageDirectory().getPath() + "/osmdroid/tiles/");
    File[] filelist = dir.listFiles();
    String[] theNamesOfFiles = new String[filelist.length];
    for (int i = 0; i < theNamesOfFiles.length; i++) {

        String temp = filelist[i].getName();
       theNamesOfFiles[i] = temp.substring(0, temp.lastIndexOf('.'));

    }
    Arrays.sort(theNamesOfFiles);
    adapter = new ArrayAdapter<String>(this, R.layout.list_row, theNamesOfFiles);

    lv.setAdapter(adapter);

    lv.setOnItemLongClickListener(new OnItemLongClickListener() {
        // setting onItemLongClickListener and passing the position to the function
                  @Override
        public boolean onItemLongClick(AdapterView<?> arg0, View arg1,
                int position, long arg3) {

                      switch(position){

                      case 0:{

                          }

                      break;

                      case 1:{

                          }
                          break;

                      case 2:{    

                          }
                          break;

                      case 3:{

                          }
                          break;

                      case 4:{

                          }

                          break;
                      }
            return true;
        }
    });
}

public void doDeleteFile(int position){

    File fileToDelete = new File(Environment.getExternalStorageDirectory().getPath() + "/osmdroid/tiles/", "A.map");

    if(!fileToDelete.isDirectory()){

        try{
            if(fileToDelete.delete()){  

                System.out.println("File delete operation success");
            }

            else{
                System.out.println("File delete operation failed");
            }
        }catch(Exception ex){
            System.out.println("Exception :"+ex.getMessage());
        }

    }else{

        System.out.println("It is  not a file");

    }

}

}

Java android ListView

来源：https://stackoverflow.com/questions/22326081/adapt-switch-method-to-a-listview-that-delete-files-in-internal-memory-of-the-ph

2条答案

按热度按时间

zysjyyx41#

我会这样做：
首先，我将有一个关于项目的数据结构。

public class MyFile {
    File file;
    String fileName;

    public MyFile(File file)
    {
        this.file = file;
        this.fileName = file.getName();
        fileName = fileName.substring(0, fileName.lastIndexOf('.'));
    }

    @Override
    public String toString() {
        return this.fileName;
    }
}
``` `toString()` 方法很重要。该方法在 `ListView` 在 `ArrayAdapter` .
然后我会像这样初始化适配器。

adapter = new ArrayAdapter(this, R.layout.list_row, arrayOfMyFileObjects);

最后在 `onItemLongClick()` 函数可以得到相应的myfile对象，如下所示

MyFile item = adapter.getItem(position);

然后您可以使用 `deleteFile(item.file);` 我认为下面的代码应该可以做到这一点。

public class MainActivity extends Activity {

ListView lv;
ArrayAdapter adapter;

public void list() {

lv = (ListView) findViewById(R.id.listView1);

File dir = new File(Environment.getExternalStorageDirectory().getPath()
        + "/osmdroid/tiles/");
File[] filelist = dir.listFiles();
ArrayList<MyFile> theNamesOfFiles = new ArrayList<MyFile>();
for (File temp : filelist) {
    theNamesOfFiles.add(new MyFile(temp));
}
Collections.sort(theNamesOfFiles, new Comparator<MyFile>() {

    @Override
    public int compare(MyFile lhs, MyFile rhs) {
        return lhs.toString().compareToIgnoreCase(rhs.toString());
    }
});
adapter = new ArrayAdapter<MyFile>(this, R.layout.list_row,
        theNamesOfFiles);

lv.setAdapter(adapter);

}

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_base);

list();

lv.setOnItemLongClickListener(new OnItemLongClickListener() {
    // setting onItemLongClickListener and passing the position to the
    // function
    @Override
    public boolean onItemLongClick(AdapterView<?> arg0, View arg1,
            int position, long arg3) {

        doDeleteFile(adapter.getItem(position).file);

        return true;
    }
});

}

public void doDeleteFile(File fileToDelete) {
if (!fileToDelete.isDirectory()) {

    try {
        if (fileToDelete.delete()) {

            System.out.println("File delete operation success");
        }

        else {
            System.out.println("File delete operation failed");
        }
    } catch (Exception ex) {
        System.out.println("Exception :" + ex.getMessage());
    }

} else {

    System.out.println("It is  not a file");

}

}

public class MyFile {
File file;
String fileName;

public MyFile(File file)
{
    this.file = file;
    this.fileName = file.getName();
    fileName = fileName.substring(0, fileName.lastIndexOf('.'));
}

@Override
public String toString() {
    return this.fileName;
}

}

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ggazkfy82#

删除项目时，也将其从数组中删除，然后在更新数组项目后在适配器上调用notifydatasetchange（）
不需要查名字。你可以按职位来做

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