我目前通过以下方式实现了SliderMenu及其自定义适配器： http://www.androidhive.info/2013/11/android-sliding-menu-using-navigation-drawer/
但是，我已将HomeFragment修改为有几个按钮，其中一个按钮创建一个自定义DialogBox。一旦出现Dialog，用户就会输入Project类的标题和描述，然后将其保存到HomeFragment中的ArrayList。此ArrayList中的对象使用此输入数据进行更新，但我的HomeFragment不显示输入数据。目前我正在尝试使用getFragmentManager（）... Transition ... replace..commit例程并尝试了许多其他不成功的方法，它给了我一个NullPointerException。我是Android开发的新手，但我想找出一种方法将这些数据传递给我的MainActivity，然后让它显示一个新的HomeFragment视图，除了显示输入的新数据。
以下是MainActivity：
//package and imports...etc.
public class MainActivity extends Activity {
private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
private ActionBarDrawerToggle mDrawerToggle;
private CharSequence mDrawerTitle;
private CharSequence mTitle;
private String[] navMenuTitles;
private TypedArray navMenuIcons;
private ArrayList<NavDrawerItem> navDrawerItems;
private NavDrawerListAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mTitle=mDrawerTitle=getTitle();
//load drawer menu items
navMenuTitles=getResources().getStringArray(R.array.nav_drawer_items);
//nav drawer icons from res
navMenuIcons=getResources().obtainTypedArray(R.array.nav_drawer_icons);
mDrawerLayout=(DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerList=(ListView) findViewById(R.id.list_slidermenu);
navDrawerItems=new ArrayList<NavDrawerItem>();
//adding nav drawer items to array
navDrawerItems.add(new NavDrawerItem(navMenuTitles[0], navMenuIcons.getResourceId(0, -1)));
navDrawerItems.add(new NavDrawerItem(navMenuTitles[1], navMenuIcons.getResourceId(1, -1)));
navDrawerItems.add(new NavDrawerItem(navMenuTitles[2], navMenuIcons.getResourceId(2, -1)));
navDrawerItems.add(new NavDrawerItem(navMenuTitles[3], navMenuIcons.getResourceId(3, -1)));
navDrawerItems.add(new NavDrawerItem(navMenuTitles[4], navMenuIcons.getResourceId(4, -1)));
navDrawerItems.add(new NavDrawerItem(navMenuTitles[5], navMenuIcons.getResourceId(5, -1)));
//RECYCLE
navMenuIcons.recycle();
//set the nav drawerlist adapter
adapter=new NavDrawerListAdapter(getApplicationContext(), navDrawerItems);
mDrawerList.setAdapter(adapter);
//enable action bar app
getActionBar().setDisplayHomeAsUpEnabled(true);
getActionBar().setHomeButtonEnabled(true);
mDrawerToggle=new ActionBarDrawerToggle(this, mDrawerLayout,
R.drawable.ic_drawer,//nav menu toggle icon
R.string.app_name,//nav drawer open - desc. for access
R.string.app_name//nav drawer close - desc. for access
){
public void onDrawerClosed(View view){
getActionBar().setTitle(mTitle);
invalidateOptionsMenu();
}
public void onDrawerOpened(View drawerView){
getActionBar().setTitle(mDrawerTitle);
invalidateOptionsMenu();
}
};
mDrawerLayout.setDrawerListener(mDrawerToggle);
if(savedInstanceState==null){
displayView(0);
}
mDrawerList.setOnItemClickListener(new SlideMenuClickListener());
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
MenuItem shareItem=(MenuItem) menu.findItem(R.id.action_share);
ShareActionProvider mShare = (ShareActionProvider) shareItem.getActionProvider();
Intent shareIntent = new Intent(Intent.ACTION_SEND);
shareIntent.setAction(Intent.ACTION_SEND);
shareIntent.setType("text/plain");
//shareIntent.putExtra(Intent.EXTRA_TEXT, "text to share");
mShare.setShareIntent(shareIntent);
return true;
}
public boolean onOptionsItemSelected(MenuItem item){
if(mDrawerToggle.onOptionsItemSelected(item)){
return true;
}
switch(item.getItemId()){
case R.id.action_settings:
return true;
default:
return super.onOptionsItemSelected(item);
}
}
//called when invalidateOptionsMenu() is triggered
@Override
public boolean onPrepareOptionsMenu(Menu menu){
boolean drawerOpen=mDrawerLayout.isDrawerOpen(mDrawerList);
menu.findItem(R.id.action_settings).setVisible(!drawerOpen);
return super.onPrepareOptionsMenu(menu);
}
@Override
public void setTitle(CharSequence title){
mTitle=title;
getActionBar().setTitle(mTitle);
}
//using ActionBarDrawerToggle: call during onPostCreate() + onConfigurationChanged()
@Override
protected void onPostCreate(Bundle savedInstanceState){
super.onPostCreate(savedInstanceState);
mDrawerToggle.syncState();
}
@Override
public void onConfigurationChanged(Configuration newConfig){
super.onConfigurationChanged(newConfig);
mDrawerToggle.onConfigurationChanged(newConfig);
}
private class SlideMenuClickListener implements ListView.OnItemClickListener {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id){
displayView(position);
}
}
private void displayView(int position){
Fragment fragment = null;
switch(position){
case 0:
fragment = new HomeFragment();
break;
case 1:
fragment = new ProjectsFragment();
break;
case 2:
fragment = new PhotosFragment();
break;
case 3:
fragment = new CommunityFragment();
break;
case 4:
fragment = new PagesFragment();
break;
case 5:
fragment = new InfoFragment();
break;
default:
break;
}
if(fragment != null){
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction().replace(R.id.frame_container, fragment).commit();
mDrawerList.setItemChecked(position, true);
mDrawerList.setSelection(position);
setTitle(navMenuTitles[position]);
mDrawerLayout.closeDrawer(mDrawerList);
} else{
Log.e("MainActivity", "Error in creating fragment");
}
}
}
这是HomeFragment代码：
//package and imports...etc.
public class HomeFragment扩展了Fragment {
public ArrayList<Project> PL;
public ArrayList<Button> DB;
public ArrayList<TextView> TL;
public ArrayList<TextView> DL;
public Adapter adp;
public View rootView;
public HomeFragment(){
PL=new ArrayList<Project>(3);
DB=new ArrayList();
TL=new ArrayList();
DL=new ArrayList();
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
rootView = inflater.inflate(R.layout.fragment_home, container, false);
final Button newProjectButton = (Button) rootView.findViewById(R.id.new_project_button);
DB.add((Button) rootView.findViewById(R.id.first_delete_button));
DB.add((Button) rootView.findViewById(R.id.second_delete_button));
DB.add((Button) rootView.findViewById(R.id.third_delete_button));
DB.add((Button) rootView.findViewById(R.id.fourth_delete_button));
TL.add((TextView) rootView.findViewById(R.id.first_tag_text));
TL.add((TextView) rootView.findViewById(R.id.second_tag_text));
TL.add((TextView) rootView.findViewById(R.id.third_tag_text));
TL.add((TextView) rootView.findViewById(R.id.fourth_tag_text));
DL.add((TextView) rootView.findViewById(R.id.first_desc_text));
DL.add((TextView) rootView.findViewById(R.id.second_desc_text));
DL.add((TextView) rootView.findViewById(R.id.third_desc_text));
DL.add((TextView) rootView.findViewById(R.id.fourth_desc_text));
newProjectButton.setOnClickListener(new View.OnClickListener(){
int i=0;
public void onClick(View v){
if(i<4){
PL.add(newProject(rootView));
upText(i, PL.get(i).getTitle(), PL.get(i).getDesc());
}
i++;
}
});
DB.get(0).setOnClickListener(new View.OnClickListener(){
public void onClick(View v){
int i=0;
Toast.makeText(getActivity(), "firstDelete: "+PL.get(0).getTitle(), Toast.LENGTH_LONG).show();
/* Do delete stuff here */
}
});
DB.get(1).setOnClickListener(new View.OnClickListener(){
public void onClick(View v){
int i=0;
Toast.makeText(getActivity(), "secondDelete: "+PL.get(1).getTitle(), Toast.LENGTH_LONG).show();
/* do delete stuff here */
}
});
DB.get(2).setOnClickListener(new View.OnClickListener(){
public void onClick(View v){
Toast.makeText(getActivity(), "thirdDelete"+PL.get(2).getTitle(), Toast.LENGTH_LONG).show();
int i=0;
/* do delete stuff here */
}
});
DB.get(3).setOnClickListener(new View.OnClickListener(){
public void onClick(View v){
Toast.makeText(getActivity(), "fourthDelete: "+PL.get(3).getTitle(), Toast.LENGTH_LONG).show();
int i =0;
/* do delete stuff here */
}
});
return rootView;
}
public void upText(int loc, String title, String desc){
TL.get(loc).setText(PL.get(loc).getTitle());
DL.get(loc).setText(PL.get(loc).getDesc());
Refresh();
}
protected void Refresh() {
Fragment f = new HomeFragment();
FragmentManager FM = getFragmentManager();
FM.beginTransaction().replace(this.getId(), f).commit();
}
public Project newProject(View view){
//create localized Project
final Project P=new Project();
//create DialogBox
final Dialog dialog = new Dialog(this.getActivity());
//modify features BEFORE setting content view
dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
dialog.setContentView(R.layout.project_dialog);
//Create EditBoxes for Dialog
final EditText titleEdit=(EditText) dialog.findViewById(R.id.dialog_title_text);
final EditText descEdit=(EditText) dialog.findViewById(R.id.dialog_description_text);
//define button's text
TextView text=(TextView) dialog.findViewById(R.id.dialog_button_create);
text.setText("Create");
Button createButton = (Button) dialog.findViewById(R.id.dialog_button_create);
// if button is clicked, close the custom dialog
createButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
P.setTitle(titleEdit.getText().toString());
P.setDesc(descEdit.getText().toString());
Toast.makeText(getActivity(), "Create button: "+P.getTitle(), Toast.LENGTH_LONG).show();
dialog.dismiss();
}
});
dialog.show();
return P;
}
}
修改
而不是使用：
Fragment f = new HomeFragment();
FragmentManager FM = getFragmentManager();
FM.beginTransaction().replace(this.getId(), f).commit();
我现在正在尝试使用：
ListView list = (ListView) getActivity().findViewById(R.id.list_slidermenu);
((BaseAdapter)list.getAdapter()).notifyDataSetChanged();
这不会给我一个NullPointerException，但不会更新列表。
答案 0 :(得分：1)
当您使用FragmentManager创建新事务时，您实际上是在抛弃现有片段，创建一个新片段，然后用现有片段替换新片段。当然，新的片段类不包含修改后的数据，因此会显示新的未修改数据。
看看这一行：
Fragment f = new HomeFragment();
你只是在创造一个全新的物体。
解除对话后，您根本不应执行任何片段事务，而只是更新现有片段的控件以反映新数据。