notifyDataSetChanged() doesn't update ListView after the adapter being notified

Question

I'm trying to make a file explorer in android and for that i have a layout with a listview (Code below).

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="500dp"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <TextView
        android:id="@+id/tvfileExplorer"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/fileExplorer"
        android:textAppearance="?android:attr/textAppearanceLarge" />
    <LinearLayout 
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal" 
        android:layout_gravity="center_horizontal">
        <Button
            android:id="@+id/bRoot"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="@dimen/margins"
            android:layout_weight=".33"
            android:text="@string/root" />
        <Button
            android:id="@+id/bOk"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="@dimen/margins"
            android:text="@string/ok" 
            android:layout_weight=".33"/>
        <Button
            android:id="@+id/bCancel"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="@dimen/margins"
            android:text="@string/cancel"
            android:layout_weight=".33" />
    </LinearLayout>    
    <ListView
        android:id="@+id/lvFileList"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="@dimen/margins" 
        android:choiceMode="multipleChoice">
    </ListView>
</LinearLayout>

After i add all the files and folders to a list i make an notifyDataSetChanged() to the list adapter. But the listview doesn't update. You can see bellow the code of the activity.

public class FileExplorer extends Activity{ 
    private File currentDirectory = new File("/");
    private List<String> directoryEntries = new ArrayList<String>();
    private ArrayAdapter<String> lvFileExplorerListAdapter;
    private Activity mActivity;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.file_explorer);        
        mActivity = this;

        lvFileExplorerListAdapter = new ArrayAdapter<String>(mActivity, android.R.layout.simple_list_item_multiple_choice, directoryEntries);

        ListView lvFileExplorerList = (ListView)findViewById(R.id.lvFileList);

        lvFileExplorerList.setAdapter(lvFileExplorerListAdapter);        

        Button bCancel = (Button)findViewById(R.id.bCancel);
        bCancel.setOnClickListener(new OnClickListener() {          
        @Override
        public void onClick(View v) {       
            finish();
        }
    });

        Button bRoot = (Button)findViewById(R.id.bRoot);
        bRoot.setOnClickListener(new OnClickListener() {            
        @Override
        public void onClick(View v) {
            browseToRoot();
        }
    });

        browseToRoot();
    }

    private void browseToRoot() {
        browseTo(new File("/"));    
    }       

    private void browseTo(final File aDirectory){
    if (aDirectory.isDirectory()){
            this.currentDirectory = aDirectory;
            fill(aDirectory.listFiles());
        }
    }

    private void fill(File[] files) {
    directoryEntries.clear();

    if(this.currentDirectory.getParent() != null)
        directoryEntries.add(getString(R.string.upOneLevel));

    int currentPathStringLenght = this.currentDirectory.getAbsolutePath().length();
    for (File file : files){                     
            directoryEntries.add(file.getAbsolutePath().substring(currentPathStringLenght));
    } 

    lvFileExplorerListAdapter.notifyDataSetChanged();
    }
}

Its important to say that the list have the values that she should have.

Any suggestion? Thanks

Answer 1

I figured out my problem...

On the layout i have the linearlayout that contains the buttons. Like you can see above i have a *match_parent* that was being drawable above the list. I changed it to wrap_content and all is ok.

Thanks for the help guys!

Answer 2

The problem is here:

directoryEntries.add(file.getAbsolutePath().substring(currentPathStringLenght));

you are adding items to directoryEntries while the adapter keeps its own copy of the data. Try to replace that line with:

lvFileExplorerListAdapter.add(file.getAbsolutePath().substring(currentPathStringLenght)) ; 

Whenever you need to change the list items you have to operate directly on the adapter.

Answer 3

您是否尝试过notifyDatasetChanged后视图无效？

lvFileExplorerList.invalidate();