android - 如何列出位于 sd 卡上的所有文件和文件夹

Question

我制作了一个程序，列出了位于 sd 卡上的所有文件和文件夹(f&f)。如果我触摸列表项之一(如果它是一个文件夹)然后列表显示位于该文件夹上的 faf。

这里是源代码

public class FileList extends ListActivity 
{
private File file;
private List<String> myList;

public void onCreate(Bundle savedInstanceState) 
{
    super.onCreate(savedInstanceState);

    myList = new ArrayList<String>();   

    String root_sd = Environment.getExternalStorageDirectory().toString();
    file = new File( root_sd + "/external_sd" ) ;       
    File list[] = file.listFiles();

    for( int i=0; i< list.length; i++)
    {
        myList.add( list[i].getName() );
    }

    setListAdapter(new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1, myList ));

}

protected void onListItemClick(ListView l, View v, int position, long id) 
{
    super.onListItemClick(l, v, position, id);

    File temp_file = new File( file, myList.get( position ) );  

    if( !temp_file.isFile())        
    {
        file = new File( file, myList.get( position ));
        File list[] = file.listFiles();

        myList.clear();

        for( int i=0; i< list.length; i++)
        {
            myList.add( list[i].getName() );
        }
        Toast.makeText(getApplicationContext(), file.toString(), Toast.LENGTH_LONG).show(); 
        setListAdapter(new ArrayAdapter<String>(this,
                android.R.layout.simple_list_item_1, myList ));

    }

}


@Override
public boolean dispatchKeyEvent(KeyEvent event) 
{
    if( KeyEvent.KEYCODE_BACK == event.getKeyCode())
    {
        String parent = file.getParent().toString();
        file = new File( parent ) ;         
        File list[] = file.listFiles();

        myList.clear();

        for( int i=0; i< list.length; i++)
        {
            myList.add( list[i].getName() );
        }
        Toast.makeText(getApplicationContext(), parent,          Toast.LENGTH_LONG).show(); 
        setListAdapter(new ArrayAdapter<String>(this,
                android.R.layout.simple_list_item_1, myList ));


    }

    return true;
}   

}

现在我有两个问题

1. 当我触摸“返回”按钮时，它会向后列出两步。说目前该列表在 "external_sd/Video/Bangla"下显示 f&f。按下后退按钮后，列表不在“external_sd/Video/”下显示f&f，而是在“external_sd/”下。

2. 有没有更好的解决方案来显示所有 f&f，如 java 中的 JFileChooser ？

Answer 1

似乎当您触摸 Back dispatchKeyEvent() 时会收到两次 KeyEvent KEYCODE_BACK，所以我建议您这样做:

public class FileList extends ListActivity 
{
private File file;
private List<String> myList;

public void onCreate(Bundle savedInstanceState) 
{
    super.onCreate(savedInstanceState);

    myList = new ArrayList<String>();   

    String root_sd = Environment.getExternalStorageDirectory().toString();
    file = new File( root_sd + "/external_sd" ) ;       
    File list[] = file.listFiles();

    for( int i=0; i< list.length; i++)
    {
            myList.add( list[i].getName() );
    }

    setListAdapter(new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1, myList ));

}

protected void onListItemClick(ListView l, View v, int position, long id) 
{
    super.onListItemClick(l, v, position, id);

    File temp_file = new File( file, myList.get( position ) );  

    if( !temp_file.isFile())        
    {
        file = new File( file, myList.get( position ));
        File list[] = file.listFiles();

        myList.clear();

        for( int i=0; i< list.length; i++)
        {
            myList.add( list[i].getName() );
        }
        Toast.makeText(getApplicationContext(), file.toString(), Toast.LENGTH_LONG).show(); 
        setListAdapter(new ArrayAdapter<String>(this,
                android.R.layout.simple_list_item_1, myList ));

    }

}


@Override
public void onBackPressed() {
            String parent = file.getParent().toString();
            file = new File( parent ) ;         
            File list[] = file.listFiles();

            myList.clear();

            for( int i=0; i< list.length; i++)
            {
                myList.add( list[i].getName() );
            }
            Toast.makeText(getApplicationContext(), parent,          Toast.LENGTH_LONG).show(); 
            setListAdapter(new ArrayAdapter<String>(this,
                    android.R.layout.simple_list_item_1, myList ));


    }