ListView仅在重新启动应用程序时更新条目(ListView updates the entry only when the application is restarted again)

 在这个应用程序中，我有一个listview和一个sqlitedatabase 。 有一个floating action button ，在单击时会显示一个dialog box其中包含两个edittext一个用于名称，另一个用于编号。 问题是，在单击dialog box的add选项后，条目未显示在listview 。 但是当activity被销毁并且在activity上再次调用onCreate ，将显示该条目。 
 
 我尝试使用adapter.notifyDataSetChanged()但它不起作用。 代码如下所示： 
 
 码 
 
public class DetailsActivity extends AppCompatActivity {

private DatabaseManager manager;
private ListView listView;
private SimpleCursorAdapter adapter;

final String[] from=new String[] {UserDatabase.NAME,UserDatabase.NUMBER};

final int[] to=new int[] {R.id.nameDisplay,R.id.phoneDisplay};


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_details);

    manager = new DatabaseManager(getApplicationContext());
    manager.open();
    Cursor cursor=manager.fetch();

    listView = (ListView) findViewById(R.id.listViewId);
    listView.setEmptyView(findViewById(R.id.empty));

    adapter = new SimpleCursorAdapter(getApplicationContext(),
            R.layout.row_item, cursor, from, to, 0);
    adapter.notifyDataSetChanged();

    listView.setAdapter(adapter);

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            final AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(DetailsActivity.this);
            LayoutInflater inflater = DetailsActivity.this.getLayoutInflater();
            final View dialogView = inflater.inflate(R.layout.custom_dialog, null);
            dialogBuilder.setView(dialogView);
            final EditText name = (EditText) dialogView.findViewById(R.id.dialogEditNmID);
            final EditText phone = (EditText) dialogView.findViewById(R.id.dialogEditPhID);

            dialogBuilder.setTitle("Add Details");
            dialogBuilder.setPositiveButton("Add", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    if (!TextUtils.isEmpty(name.getText().toString()) &&
                            !TextUtils.isEmpty(phone.getText().toString())) {
                        /*adapter.notifyDataSetChanged();
                        manager.insert(name.getText().toString(), phone.getText().toString());
                        Toast.makeText(getApplicationContext(),
                                "Added " + name.getText().toString(), Toast.LENGTH_SHORT).show();*/
                        insertData(name.getText().toString(),phone.getText().toString());
                    } else {
                        Toast.makeText(getApplicationContext(),
                                "Empty field(s)", Toast.LENGTH_SHORT).show();
                    }

                }
            });

            dialogBuilder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    dialog.dismiss();
                }
            });

            AlertDialog b = dialogBuilder.create();
            b.show();
            //  listView.setAdapter(adapter);
            //adapter.notifyDataSetChanged();
        }
    });
}

public void insertData(String fname,String phnumber){
    manager.insert(fname,phnumber);
    listView.setAdapter(adapter);
    adapter.notifyDataSetChanged();
}
}
 
 一些陈述被评论，因为我试图得到所需的结果，但无法得到它。 

In this application, I have a listview and a sqlitedatabase. There is a floating action button which on clicking displays a dialog box containing two edittext one for name and another for number. The problem is that the after clicking on the add option of the dialog box the entry is not shown on the listview. But when the activity is destroyed and onCreate is called again on the activity , the entry is shown. 
 
I tried using adapter.notifyDataSetChanged() but it doesn't work. The code is shown below :
 
Code
 
public class DetailsActivity extends AppCompatActivity {

private DatabaseManager manager;
private ListView listView;
private SimpleCursorAdapter adapter;

final String[] from=new String[] {UserDatabase.NAME,UserDatabase.NUMBER};

final int[] to=new int[] {R.id.nameDisplay,R.id.phoneDisplay};


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_details);

    manager = new DatabaseManager(getApplicationContext());
    manager.open();
    Cursor cursor=manager.fetch();

    listView = (ListView) findViewById(R.id.listViewId);
    listView.setEmptyView(findViewById(R.id.empty));

    adapter = new SimpleCursorAdapter(getApplicationContext(),
            R.layout.row_item, cursor, from, to, 0);
    adapter.notifyDataSetChanged();

    listView.setAdapter(adapter);

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            final AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(DetailsActivity.this);
            LayoutInflater inflater = DetailsActivity.this.getLayoutInflater();
            final View dialogView = inflater.inflate(R.layout.custom_dialog, null);
            dialogBuilder.setView(dialogView);
            final EditText name = (EditText) dialogView.findViewById(R.id.dialogEditNmID);
            final EditText phone = (EditText) dialogView.findViewById(R.id.dialogEditPhID);

            dialogBuilder.setTitle("Add Details");
            dialogBuilder.setPositiveButton("Add", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    if (!TextUtils.isEmpty(name.getText().toString()) &&
                            !TextUtils.isEmpty(phone.getText().toString())) {
                        /*adapter.notifyDataSetChanged();
                        manager.insert(name.getText().toString(), phone.getText().toString());
                        Toast.makeText(getApplicationContext(),
                                "Added " + name.getText().toString(), Toast.LENGTH_SHORT).show();*/
                        insertData(name.getText().toString(),phone.getText().toString());
                    } else {
                        Toast.makeText(getApplicationContext(),
                                "Empty field(s)", Toast.LENGTH_SHORT).show();
                    }

                }
            });

            dialogBuilder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    dialog.dismiss();
                }
            });

            AlertDialog b = dialogBuilder.create();
            b.show();
            //  listView.setAdapter(adapter);
            //adapter.notifyDataSetChanged();
        }
    });
}

public void insertData(String fname,String phnumber){
    manager.insert(fname,phnumber);
    listView.setAdapter(adapter);
    adapter.notifyDataSetChanged();
}
}
 
Some of the statements are commented because I tried to get the desired result but couldn't get it.

原文：https://stackoverflow.com/questions/46791482