我正在编写一个用于浏览文件系统的 DialogFragment，它现在非常好用。我刚遇到一个问题。
文件显示在 ListView 中，当用户选择文件时，此事件将发送到通过 OnFileSelectedListener-Interface 调用 Fragment 的 Activity。这对文件来说很好，但是将目录名称发送到活动，然后销毁并重新创建片段，当所有应该发生的事情是片段应该显示一个新目录时，感觉是错误的。它也使整个 Fragment 消失然后重新出现，这不是很流畅。
此外，每个使用 Fragment 的 Activity 都必须使用重新创建 Fragment 的逻辑，这与“不要重复自己”相去甚远。
所以，简而言之，有没有办法在 Fragment 中更改 Listview？不幸的是，多次调用 AlertDialog.Builder 是行不通的。
这是我的 DialogFragment。我希望可以发布整个内容：
package de.fusionsystems.firmenlaufmonitor;
import java.io.File;
import java.util.ArrayList;
import java.util.Arrays;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.app.DialogFragment;
import android.content.Context;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;
public class FileChooserFragment extends DialogFragment {
private OnFileSelectedListener mCallback;
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
return createDialog();
}
private AlertDialog createDialog(){
// Create the AlertDialog object and return it
SharedPreferences options = PreferenceManager.getDefaultSharedPreferences(getActivity());
ArrayList<File> files = getFilesInDir(options.getString("BaseDir", ""));
ArrayList<ListEntry> fileEntries = new ArrayList<ListEntry>();
if (!isBaseDir(options.getString("BaseDir", ""))){
fileEntries.add(new ListEntry("..", getResources().getDrawable( R.drawable.ic_folder)));
}
for (File file : files){
if (file.isDirectory()){
fileEntries.add(new ListEntry(file.getName(),getResources().getDrawable(R.drawable.ic_folder)));
}else{
if (file.getName().endsWith(".kml")){
fileEntries.add(new ListEntry(file.getName(),getResources().getDrawable( R.drawable.ic_file)));
}
}
}
final FileAdapter adapter = new FileAdapter(getActivity(), fileEntries);
OnClickListener clickListener = new OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
String path;
SharedPreferences options = PreferenceManager.getDefaultSharedPreferences(getActivity());
if (adapter.getItem(which).name.equals("..")){
//navigate back
path = options.getString("BaseDir", "/");
path=path.substring(0, path.length());
path=path.substring(0,path.lastIndexOf("/"));
path = !path.equals("")?path:("/");
}else {
path = options.getString("BaseDir", "");
path += ((path.equals("/"))?(""):("/"))+adapter.getItem(which).name;
}
Log.d("Path", path);
Editor editor = options.edit();
File dirTest = new File(path);
if (dirTest.isDirectory()){
editor.putString("BaseDir", path);
editor.commit();
//mCallback.onFileSelected("");
//createDialog();
//*******************DO THE RIGHT THING HERE***********************
}else{
mCallback.onFileSelected(path);
}
}
};
// Use the Builder class for convenient dialog construction
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setAdapter(adapter, clickListener)
.setNegativeButton("Abbrechen", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dismiss();
}
});
builder.setTitle("Datei wählen");
return builder.create();
}
private ArrayList<File> getFilesInDir(String dir) {
File folder = new File(dir);
if (!folder.exists()){
folder = new File("/");
if (!folder.exists()){
Log.e("FileBrowser","Something's really fishy");
}
}
ArrayList<File> fileList = new ArrayList<File>(Arrays.asList(folder.listFiles()));
return fileList;
}
private boolean isBaseDir(String dir) {
File folder = new File(dir);
if (!folder.exists()){
folder = new File("/");
if (!folder.exists()){
Log.e("FileBrowser","Something's really fishy");
}
}
File baseDir = new File("/");
if (folder.equals(baseDir)){
return true;
}else{
return false;
}
}
// Container Activity must implement this interface
public interface OnFileSelectedListener {
public void onFileSelected(String file);
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
// This makes sure that the container activity has implemented
// the callback interface. If not, it throws an exception
try {
mCallback = (OnFileSelectedListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnHeadlineSelectedListener");
}
}
class ListEntry {
public String name;
public Drawable item ;
public ListEntry(String name, Drawable item) {
this.name = name;
this.item = item;
}
}
class FileAdapter extends ArrayAdapter<ListEntry>{
public FileAdapter(Context context, ArrayList<ListEntry> fileEntry) {
super(context, R.layout.filechooser_list_item,fileEntry);
}
@Override
public View getView(int position, View convertView, ViewGroup parent){
ListEntry entry = getItem(position);
// Check if an existing view is being reused, otherwise inflate the view
if (convertView == null) {
convertView = LayoutInflater.from(getContext()).inflate(R.layout.filechooser_list_item, parent, false);
}
// Lookup view for data population
TextView filechooserEntry = (TextView) convertView.findViewById(R.id.filechooser_entry);
// Populate the data into the template view using the data object
filechooserEntry.setText(entry.name);
filechooserEntry.setCompoundDrawablesWithIntrinsicBounds(entry.item, null, null, null);
// Return the completed view to render on screen
return convertView;
}
}
}