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我创建了一个ArrayListwith custom ArrayAdater。每个都ListItem包含 aCheckBox和 a TextView

TextView 包含目录的名称,而 CheckBox 指示是否应扫描该目录。

我正在维护一个ArrayList存储所有已检查目录名称的目录。ListView 中有一些buttons向下。

最初,当我选中/取消选中应用程序时,ArrayList 工作正常并在其中添加/删除元素。

但是当我按下任何按钮时,ArrayList 会冻结并且不会添加/删除元素。

下面的代码:(对不起,长度)

MainActivity 类:

public class MainActivity extends ListActivity implements OnClickListener {

    Button done, cancel, selectAll, back;
    ListView listView;
    ArrayAdapter<Directory> adapter;
    List<Directory> list;
    ArrayList<String> checkedList;
    private final static String ROOT = "/";
    private String currentDir; // Used at the time of back button press

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        try {
            setContentView(R.layout.main);
            checkedList = new ArrayList<String>();
            done = (Button) findViewById(R.id.bDone);
            back = (Button) findViewById(R.id.bBack);
            cancel = (Button) findViewById(R.id.bCancel);
            selectAll = (Button) findViewById(R.id.bSelAll);
            done.setOnClickListener(this);
            back.setOnClickListener(this);
            cancel.setOnClickListener(this);

            currentDir = ROOT;
            new AsyncHandler(this, ROOT).execute();
        } catch (Exception e) {
            Toast.makeText(this, e.toString(), Toast.LENGTH_SHORT).show();
        }
    }

    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        // super.onListItemClick(l, v, position, id);
        try {
            Directory d = list.get(position);
            File f = d.getFile();
            if (f.isDirectory() && f.canRead()) {
                // Updating View on List TextView item click
                currentDir = f.getAbsolutePath();
                new AsyncHandler(this, f.getAbsolutePath()).execute();
            } else {
                Toast.makeText(this, f.getName() + " NOT READABLE",
                        Toast.LENGTH_SHORT).show();
            }
        } catch (Exception e) {
            Toast.makeText(this, e.toString(), Toast.LENGTH_SHORT).show();
        }
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
        case R.id.bDone:
            ArrayList<String> localCheckedList = checkedList;
            checkedList = filterCheckedList();
            String allCkecdDirs = "";
            for (int i = 0; i < checkedList.size(); i++) {
                allCkecdDirs = allCkecdDirs + "\n" + checkedList.get(i);
            }
            Toast.makeText(this, allCkecdDirs, Toast.LENGTH_LONG).show();
            break;
        case R.id.bBack:
            if(!currentDir.equals(ROOT)){
                /*
                 * here backtracking current directory one step
                 * if current die = /mnt/sdcard/music
                 * so now it will be /mnt/sdcard
                 * this is because if Back button is pressed, 
                 * in ElementAdapter while rendering elements 
                 * the currentDir will become /mnt/sdcard/music/music  
                 */
                currentDir = new File(currentDir).getParent();  
                new AsyncHandler(this, currentDir).execute();
            }else{
                Toast.makeText(this, "Listing already at Root Folder", Toast.LENGTH_LONG).show();
            }
            break;
        case R.id.bCancel:
            this.finish();
            break;
        }
    }

    private ArrayList<String> filterCheckedList() {
        /*
         * Removing duplicates
         */
        HashSet hs = new HashSet();
        hs.addAll(checkedList);
        checkedList.clear();
        checkedList.addAll(hs);

        /*
         * Deleting sub-folders if their parent folder has already been added in
         * the list
         */
        Collections.sort(checkedList);
        ArrayList<String> filteredList = new ArrayList<String>();
        for (int i = 0; i < checkedList.size(); i++) {
            File current = new File(checkedList.get(i));
            File parent = current;
            while ((parent = parent.getParentFile()) != null) {
                if (checkedList.contains(parent.getAbsolutePath())) {
                    current = parent;
                }
            }
            if (current != null
                    && !filteredList.contains(current.getAbsolutePath())) {
                filteredList.add(current.getAbsolutePath());
            }
        }
        checkedList = filteredList;
        return checkedList;
    }

    public class AsyncHandler extends AsyncTask {

        Context context;
        String currentFolder;
        private List<Directory> prevList;

        public AsyncHandler(Context c, String currentFolder) {
            this.context = c;
            this.currentFolder = currentFolder;
        }

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
        }

        @Override
        protected Object doInBackground(Object... arg0) {
            getList();
            return null;
        }

        @Override
        protected void onPostExecute(Object result) {
            /*
             * Checking if list does not contain any directory. If it does not
             * then the previous view's list is treated as current list and
             * rendered again.
             */
            if (list.size() == 0) {
                Toast.makeText(context, "No Sub Directory", Toast.LENGTH_SHORT)
                        .show();
                list = prevList;
            }
            setListAdapter(new ElementAdapter(context, list, checkedList, currentDir));
        }

        private void getList() {
            prevList = list;
            list = new ArrayList<Directory>();
            File root = new File(currentFolder);
            File[] files = root.listFiles();
            for (File f : files) {
                if (f.isDirectory() && !f.isHidden() && f.canRead()) {
                    list.add(new Directory(f, f.getName()));
                }
            }
        }
    }
}

数组适配器类:

public class ElementAdapter extends ArrayAdapter {
    private Context context;
    private List<Directory> list;
    ArrayList<String> checkedList;
    public final String fileName = "AudioSessionFile";
    SharedPreferences sharedAudioPrefrences;
    private static String currentDir;   // This will be appended at the time when
                                        // chcing if the checkbox is aready
                                        // checked or not

    public ElementAdapter(Context c, List<Directory> list,
            ArrayList checkedList, String currentDir) {
        super(c, R.layout.row, list);
        this.context = c;
        sharedAudioPrefrences = c.getSharedPreferences(fileName,
                Context.MODE_PRIVATE);
        this.list = list;
        this.checkedList = checkedList;
        this.currentDir = currentDir;
    }

    static class ViewHolder {
        protected TextView textView;
        protected CheckBox checkBox;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder = null;
        View view = convertView;
        if (view == null) {
            LayoutInflater inflator = (LayoutInflater) context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            view = inflator.inflate(R.layout.row, null);
            viewHolder = new ViewHolder();
            viewHolder.textView = (TextView) view.findViewById(R.id.tvElement);
            viewHolder.checkBox = (CheckBox) view.findViewById(R.id.checkBox1);
            viewHolder.checkBox
                    .setOnCheckedChangeListener(new OnCheckedChangeListener() {

                        @Override
                        public void onCheckedChanged(CompoundButton buttonView,
                                boolean isChecked) {
                            int getPosition = (Integer) buttonView.getTag();
                            list.get(getPosition).setSelected(
                                    buttonView.isChecked());

                            /*
                             * Code to check if checkbox is checked on
                             * unchecked. If checked then, the corresponding
                             * entry is made in the HashMap (which contains the
                             * state of directories to be scanned)
                             */
                            if (isChecked
                                    && !checkedList.contains(list
                                            .get(getPosition).getFile()
                                            .getAbsolutePath())) {
                                /*
                                 * Here we can also put condition &&
                                 * !checkedList
                                 * .contains(list.get(getPosition).getFile
                                 * ().getParent()) to avoid creating unnecessary
                                 * entries
                                 */
                                checkedList.add(list.get(getPosition).getFile()
                                        .getAbsolutePath());
                            } else if (!isChecked
                                    && checkedList.contains(list
                                            .get(getPosition).getFile()
                                            .getAbsolutePath())) {
                                checkedList.remove(list.get(getPosition)
                                        .getFile().getAbsolutePath());
                            }
                        }
                    });
            view.setTag(viewHolder);
            view.setTag(R.id.tvElement, viewHolder.textView);
            view.setTag(R.id.checkBox1, viewHolder.checkBox);
        } else {
            viewHolder = (ViewHolder) view.getTag();
        }
        viewHolder.checkBox.setTag(position);
        viewHolder.textView.setText(list.get(position).getName());
        viewHolder.checkBox.setChecked(list.get(position).isSelected());

        /*
         * checking if the directory is already selected earlier by the user
         */
        String absPath = currentDir + "/" +  viewHolder.textView.getText();
        if (checkedList != null
                && checkedList.contains(absPath)) {
            viewHolder.checkBox.setChecked(true);
        }

        return view;
    }
}

虽然代码确实进入了 ElementAdapter 中的 onCheckedChangeListener,但是当流返回到 Activity 类时,列表保持原样。

4

1 回答 1

0

尝试在语句notifyDataSetChanged() 之后添加。setListAdapter(new ElementAdapter(context, list, checkedList, currentDir))

例如:

   ElementAdapter myAdpt = new ElementAdapter(context, list, checkedList, currentDir)
   setListAdapter(myAdpt);
   myAdpt.notifyDataSetChanged();
于 2012-07-14T18:34:15.023 回答