android - 使用确认对话框删除 ListView 中的项目

Question

我目前正在制作一个“联系人”应用程序作为我的 Android 主题的最终项目。当我单击列表中的项目时，它应该显示 this使用选项编辑和删除。单击删除按钮后，应显示 this confirmation单击确定后如何从 ListView 中删除项目？这是我的代码。

MainActivtity.java

public class MainActivity extends AppCompatActivity {
    ImageButton floatButton;
    private ContactsAdapter mContactsAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    floatButton = (ImageButton) findViewById(R.id.imagebutton);
    floatButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Toast.makeText(getApplicationContext(),
                    "Add New Contact", Toast.LENGTH_LONG).show();
           addContact();

        }
    });
    mContactsAdapter = new ContactsAdapter();
    ListView listNote = (ListView)findViewById(R.id.listView);
    listNote.setAdapter(mContactsAdapter);
    listNote.setLongClickable(true);


    listNote.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
        @Override
        public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
           mContactsAdapter.deleteContact(position);
            return true;
        }
    });


    listNote.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int whichItem, long id) {


            Contacts tempContact = mContactsAdapter.getItem(whichItem);

            DialogShowContact dialog = new DialogShowContact();
            dialog.sendContactSelected(tempContact);
            dialog.show(getFragmentManager(), "");
            Toast.makeText(getApplicationContext(),
                    "Item clicked", Toast.LENGTH_LONG).show();

        }
    });

}
public void createNewContact(Contacts n) {
    mContactsAdapter.addContact(n);
}
public void editNewContact(Contacts n) {
    mContactsAdapter.addContact(n);
}

public void addContact() {
    DialogNewContact dialog = new DialogNewContact();
    dialog.show(getFragmentManager(), "");

}

public void editContact() {
    DialogEditContact dialog = new DialogEditContact();
    dialog.show(getFragmentManager(), "");

}


public void deleteContact() {
    DialogDeleteContact dialog = new DialogDeleteContact();
    dialog.show(getFragmentManager(), "");

}

ContactsAdapter.java

public class ContactsAdapter extends BaseAdapter{
    private JSONSerializer mSerializer;

    List<Contacts> contactsList = new ArrayList<Contacts>();
    public ContactsAdapter(){
        mSerializer = new JSONSerializer("NotetoSelf.json",MainActivity.this.getApplicationContext());

        try{
            contactsList= mSerializer.load();
        }catch (Exception e) {
            contactsList = new ArrayList<Contacts>();
            Log.e("Error loading notes: ", "", e);
        }}
    public void addContact(Contacts c){
        contactsList.add(c);
        saveContacts();
        notifyDataSetChanged();
    }

    public void deleteContact(int c){
        contactsList.remove(c);
        saveContacts();
        notifyDataSetChanged();
    }



    public void saveContacts(){
        try{
            mSerializer.save(contactsList);
        }catch (Exception e){
            Log.e("Error Saving notes: ","",e);
        }
    }
    public int getCount() {
        return contactsList.size();
    }

    public Contacts getItem(int whichItem) {
        return contactsList.get(whichItem);
    }


    public long getItemId(int whichItem) {
        return whichItem;
    }

    public View getView(int whichItem, View view, ViewGroup viewGroup){
        if(view == null){
            LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            view = inflater.inflate(R.layout.list_item, viewGroup, false);
        }

        //Grab a referece to all our TextView and ImageView Widgets
        TextView txtName = (TextView) view.findViewById(R.id.lName);
        TextView txtNum = (TextView) view.findViewById(R.id.lNum);

        Contacts tempContacts = contactsList.get(whichItem);

        txtName.setText(tempContacts.getmName());
        txtNum.setText(tempContacts.getmNum());
        return view;

    }




  }


}

Contacts.java

public class Contacts {
    private String mName;
    private String mNum;

public static final String JSON_NAME = "name";
private static final String JSON_NUM = "num";

public Contacts(JSONObject jo) throws JSONException {
    mName = jo.getString(JSON_NAME);
    mNum = jo.getString(JSON_NUM);
}

public Contacts(){

}

public JSONObject convertToJSON() throws JSONException{
    JSONObject jo = new JSONObject();

    jo.put(JSON_NAME,mName);
    jo.put(JSON_NUM,mNum);
    return jo;
}

public String getmName() {
    return mName;
}

public void setmName(String mName) {
    this.mName = mName;
}

public String getmNum() {
    return mNum;
}

public void setmNum(String mNum) {
    this.mNum = mNum;


  }

}

JSONserializer.java

public class JSONSerializer {

    private String mFilename;
    private Context mContext;


public JSONSerializer(String fn, Context con)
{
    mFilename = fn;
    mContext = con;
}

public void save (List<Contacts> contacts) throws IOException, JSONException
{
    //Make an array in JSON format
    JSONArray jArray = new JSONArray();

    //And load it with the notes
    for (Contacts c : contacts)
        jArray.put(c.convertToJSON());

    //Now write it to the private disk space of our app
    Writer writer = null;
    try
    {
        OutputStream out = mContext.openFileOutput(mFilename,mContext.MODE_PRIVATE);
        writer = new OutputStreamWriter(out);
        writer.write(jArray.toString());
    }
    finally
    {
        if(writer != null)
        {
            writer.close();
        }
    }
}



public ArrayList<Contacts> load() throws IOException, JSONException
{
    ArrayList<Contacts> contactsList = new ArrayList<Contacts>();
    BufferedReader reader = null;
    try
    {
        InputStream in = mContext.openFileInput(mFilename);
        reader = new BufferedReader(new InputStreamReader(in));
        StringBuilder jsonString = new StringBuilder();
        String line = null;

        while((line = reader.readLine()) != null)
        {
            jsonString.append(line);
        }
        JSONArray jArray = (JSONArray) new JSONTokener(jsonString.toString()).nextValue();
        for(int i = 0; i < jArray.length(); i++)
        {
            contactsList.add(new Contacts(jArray.getJSONObject(i)));
        }
    }
    catch(FileNotFoundException e)
    {

    }
    finally {
        if(reader!=null)
            reader.close();
    }
    return contactsList;
}


}//--------->end of JSONserializer

DialogShowContact.java

public class DialogShowContact extends DialogFragment {
    private MainActivity.ContactsAdapter mContactsAdapter;
    private Contacts mContact;
    @Override
public Dialog onCreateDialog(Bundle savedInstanceState){
    AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());

    LayoutInflater inflater = getActivity().getLayoutInflater();
    View dialogView = inflater.inflate(R.layout.view_contact, null);

    TextView txtTitle = (TextView) dialogView.findViewById(R.id.vName);
    TextView txtDescription = (TextView) dialogView.findViewById(R.id.vNum);

    txtTitle.setText(mContact.getmName());
    txtDescription.setText(mContact.getmNum());


    Button btnEdit = (Button)dialogView.findViewById(R.id.vEdit);
    Button btnDelete = (Button)dialogView.findViewById(R.id.vDelete);
    builder.setView(dialogView).setMessage("Contact");

    btnEdit.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
          //  dismiss();

            DialogEditContact myDialog = new DialogEditContact();
            myDialog.show(getFragmentManager(), "123");
        }
    });

    btnDelete.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        DeleteConfirmation myDialog = new DeleteConfirmation();
         myDialog.show(getFragmentManager(), "123");
          // MainActivity a = new MainActivity();
            //mContactsAdapter.deleteContact();



        }
    });
    return builder.create();
}

//Receive a note from the MainActivity
public void sendContactSelected(Contacts contactsSelected){
    mContact=contactsSelected;
}
}

DeleteConfirmation.java

public class DeleteConfirmation extends DialogFragment {

    private MainActivity.ContactsAdapter mContactsAdapter;
public Dialog onCreateDialog (Bundle savedInstanceState){
    //Use Builder class because this dialog has a simple Ui
    AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());

    //Dialog will have Make a selection as the title

    builder.setMessage("Delete Contact?")

    //An ok button that does nothing

    .setPositiveButton("OK", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int id) {
            //(HOW TO CALL THE DELETE OR DO DELETING AFTER CLICKING OK???
        }
    })

            // A "Cancel" button that does nothing

    .setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int id) {


        }
    });


    //Create the object and return it
    return builder.create();



    }//End onCreateDialog
}

Answer 1

单击确定后如何从 ListView 中删除项目？

• 听 OK Action
• 当用户单击“确定”时，从列表中删除联系人，然后调用

listNote.getAdapter.notifyDataSetChanged;

您的问题是如何获取dialogFragment中ContactsAdapter的引用？您应该调用 getActivity() 并转换为 MainActivtity。然后你应该为你的mContactsAdapter设置一个getter，最后调用你的deleteContact方法，它会通知数据改变