Question

我正在制作一个Android应用程序，需要将SD卡上特定目录中的所有项目显示到列表视图中。我已经去过几个教程，但似乎没有人给我任何帮助。我已设法添加和删除我的SD卡和列表视图中的内容。但我需要将目录中的项目（文件）显示在listview上。我正在使用动态列表视图。请提前帮助和谢谢！这是我到目前为止使用的代码，我需要阅读onCreate方法中的项目。

public class NotesActivity extends ListActivity implements OnClickListener {
/** Called when the activity is first created. */
List<String> myList = new ArrayList<String>();
EditText AddItemToListViewEditText;
Button AddItemToListView, AddItemToListViewButton, CancelButton, DeleteButton,CancelButton2, DeleteAllButton;
LinearLayout AddItemToListViewLinearLayout, DeleteItemFromListViewLinearLayout, DeleteAllItemsFromListViewLinearLayout;
public int DeleteIndexNumber;
public String NameOfSaveItemToSdCard = "";
public String NameOfDeleteItemFromSdCard = "";
public int DeleteIndexNumber2;
  static final String[] COUNTRIES = new String[] {
      "Matte på A1 med Ole", "Engelsk på klasserommet", "Film på A1 etter friminuttet"
      };
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.notes);
    setListAdapter((ListAdapter) new ArrayAdapter<String>(this, R.layout.list_item, COUNTRIES));
    setListAdapter((ListAdapter) new ArrayAdapter<String>(this, R.layout.list_item, myList));

    ListView lv = getListView();
    lv.setTextFilterEnabled(true);

    lv.setOnItemClickListener(new OnItemClickListener() {
      public void onItemClick(AdapterView<?> parent, View view,
          int position, long id) {
        // When clicked, show a toast with the TextView text
        Toast.makeText(getApplicationContext(), "Note: " + ((TextView) view).getText(),
            Toast.LENGTH_SHORT).show();
        DeleteIndexNumber = position;
        DeleteIndexNumber2 = position;
        NameOfDeleteItemFromSdCard = myList.get(position);
        DeleteItemFromListViewLinearLayout = (LinearLayout)findViewById(R.id.DeleteItemFromListViewLinearLayout);
        DeleteItemFromListViewLinearLayout.setVisibility(View.VISIBLE);
  }
    });
  }
@Override
public boolean onCreateOptionsMenu(Menu meny) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.listviewmenubuttons, meny);
    return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch(item.getItemId()) {
    case R.id.AddItemToListView:
        AddItemToListViewButton = (Button)findViewById(R.id.AddItemToListViewButton);
        CancelButton = (Button)findViewById(R.id.CancelButton);
        DeleteButton = (Button)findViewById(R.id.DeleteButton);
        CancelButton.setOnClickListener(this);
        DeleteButton.setOnClickListener(this);
        AddItemToListViewLinearLayout = (LinearLayout)findViewById(R.id.AddItemToListViewLinearLayout);
        AddItemToListViewButton.setOnClickListener(this);
        AddItemToListViewLinearLayout.setVisibility(View.VISIBLE);
        break;
    case R.id.DeleteAllNotes:
        DeleteAllItemsFromListViewLinearLayout = (LinearLayout)findViewById(R.id.DeleteAllItemsFromListViewLinearLayout);
        DeleteAllItemsFromListViewLinearLayout.setVisibility(View.VISIBLE);
        CancelButton2 = (Button)findViewById(R.id.CancelButton2);
        DeleteAllButton = (Button)findViewById(R.id.DeleteAllButton);
        CancelButton2.setOnClickListener(this);
        DeleteAllButton.setOnClickListener(this);
        break;
        }
    return true;
}
public void onClick(View src) {
    switch(src.getId()) {
    case R.id.AddItemToListViewButton:
        AddItemToListViewEditText = (EditText)findViewById(R.id.AddItemToListViewEditText);
        myList.add(AddItemToListViewEditText.getText().toString());
        NameOfSaveItemToSdCard = AddItemToListViewEditText.getText().toString();
        ((ArrayAdapter)getListView().getAdapter()).notifyDataSetChanged(); 
        AddItemToListViewEditText.setText("");
        AddItemToListViewEditText.clearFocus();
        InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
        imm.toggleSoftInput (InputMethodManager.SHOW_FORCED, InputMethodManager.RESULT_HIDDEN);
        imm.toggleSoftInput(InputMethodManager.SHOW_FORCED, 0);
        AddItemToListViewLinearLayout.setVisibility(View.GONE);
        //Check if directory exists
        checkIfDirectoryExist();
        break;
    case R.id.CancelButton:
        DeleteItemFromListViewLinearLayout = (LinearLayout)findViewById(R.id.DeleteItemFromListViewLinearLayout);
        DeleteItemFromListViewLinearLayout.setVisibility(View.INVISIBLE);
        break;
    case R.id.DeleteButton:
        myList.remove(DeleteIndexNumber);
        ((ArrayAdapter)getListView().getAdapter()).notifyDataSetChanged();
        File f = new File(Environment.getExternalStorageDirectory() + "/SchoolAppNotes/" + NameOfDeleteItemFromSdCard);
        if(f.exists()) {
            boolean deleted = f.delete();
        }
        DeleteItemFromListViewLinearLayout = (LinearLayout)findViewById(R.id.DeleteItemFromListViewLinearLayout);
        DeleteItemFromListViewLinearLayout.setVisibility(View.INVISIBLE);
        break;
    case R.id.DeleteAllButton:
        myList.removeAll(myList);
        ((ArrayAdapter)getListView().getAdapter()).notifyDataSetChanged();
        DeleteAllItemsFromListViewLinearLayout = (LinearLayout)findViewById(R.id.DeleteAllItemsFromListViewLinearLayout);
        DeleteAllItemsFromListViewLinearLayout.setVisibility(View.INVISIBLE);
        break;
    case R.id.CancelButton2:
        DeleteAllItemsFromListViewLinearLayout = (LinearLayout)findViewById(R.id.DeleteAllItemsFromListViewLinearLayout);
        DeleteAllItemsFromListViewLinearLayout.setVisibility(View.INVISIBLE);
        break;
    }
}
private void checkIfDirectoryExist() {
    // TODO Auto-generated method stub
    File f = new File(Environment.getExternalStorageDirectory() + "/SchoolAppNotes");
    if(f.exists()) {
        try {
            OutputStream output = new FileOutputStream(Environment.getExternalStorageDirectory()
                     + "/SchoolAppNotes/" + NameOfSaveItemToSdCard);
            Toast.makeText(getApplicationContext(), "File created:-)",
                    Toast.LENGTH_SHORT).show();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            Toast.makeText(getApplicationContext(), "We failed to create the file",
                    Toast.LENGTH_SHORT).show();
            e.printStackTrace();
        }
    }
    else {
        //Create directory
        File folder = new File(Environment.getExternalStorageDirectory() + "/SchoolAppNotes");
        boolean success = false;
        if(!folder.exists())
        {
            success = folder.mkdir();
        }         
        if (!success) 
        { 
            // Do something on success
//Writing file...(It doesn't work)
        }
        else 
        {
            // Do something else on failure 
        }
        checkIfDirectoryExist();
    }
}
}

Answer 1

我假设myList应该保存你目录中的文件名？看起来你从未实例化它。

要做到这一点，您需要获取文件名列表并在将其用于制作适配器之前将其加载到那里。

所以在.setAdapter（）调用之前添加类似的东西：

File mFile = new File(Environment.getExternalStorageDirectory() + "yourDirectory");
myList = mFile.list();

如果正确填充阵列，你应该好好去。

P.S。 File.list() docs

编辑：

哎呀，没注意到myList上的类型。请改用

myList = Arrays.asList(mFile.list());

在android中读取目录到listview的项目

1 个答案: