我无法从android中的片段读取活动中的数据库信息

Question

I'm beginner in android programmation but and I have difficulty to read sqlite database information in activity from fragment.

That is my Fragment activity:

package cm.mavis.easylife.les_fragment;

import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.v4.app.Fragment;
import android.support.v7.app.AlertDialog;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import cm.mavis.easylife.ChoixRecherche;
import cm.mavis.easylife.DataHelper;
import cm.mavis.easylife.LectureInfos;
import cm.mavis.easylife.R;

public class FragmentRecherche extends Fragment {
String[] liste;
protected Cursor cursor;
DataHelper dbcenter;
ListView  listview;
public static Context fragmentRecherche;


public static FragmentRecherche newInstance() {
    FragmentRecherche fragment = new FragmentRecherche();
    return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);


}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_recherche, container, false);

    FloatingActionButton floatingActionButton = rootView.findViewById(R.id.fab);
    floatingActionButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Intent intent = new Intent(getContext(), ChoixRecherche.class);
            startActivity(intent);
        }
    });


    listview = rootView.findViewById(R.id.liste_recherche);

    fragmentRecherche = getActivity();
    dbcenter = new DataHelper(getActivity());
    RefreshList();


    return rootView;
}

public void RefreshList() {
SQLiteDatabase database = dbcenter.getReadableDatabase();
cursor = database.rawQuery("select * from cni_perdu", null);
liste = new String[cursor.getCount()];
cursor.moveToFirst();

for (int cc = 0; cc < cursor.getCount(); cc++){
    cursor.moveToPosition(cc);
    liste[cc] = cursor.getString(1);
}

listview.setAdapter(new ArrayAdapter(getActivity(), android.R.layout.simple_list_item_1, liste));
listview.setSelected(true);

listview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
    @Override
    public void onItemClick(AdapterView arg0, View arg1, int arg2, long arg3) {

        final String selection = liste[arg2];
        final CharSequence[] dialogitem = {"Voir", "Suprimer"};

        AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
        builder.setTitle("Option");
        builder.setIcon(R.drawable.mes_voyage);
        builder.setItems(dialogitem, new DialogInterface.OnClickListener(){
            public void onClick(DialogInterface dialog, int item){
                switch (item){
                    case 0:

                        Intent intent = new Intent(getActivity(), LectureInfos.class);
                        intent.putExtra("", selection);
                        startActivity(intent);
                        RefreshList();
                        break;

                    case 1:
                        SQLiteDatabase database = dbcenter.getWritableDatabase();
                        database.execSQL("delete from cni_perdu where prenom = '" + selection + "'");
                        dbcenter.close();
                        RefreshList();
                        break;
                }
            }
        });
        builder.create().show();
    }
});
    ((ArrayAdapter)listview.getAdapter()).notifyDataSetInvalidated();

}
@Override
}

  int id = item.getItemId();

    if (id == R.id.action_settings) {
     return super.onOptionsItemSelected(item);
  }
}

And that is my activity:

package cm.mavis.easylife;

import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.TextView;

public class LectureInfos extends AppCompatActivity {
DataHelper dataHelper;
protected Cursor cursor;
TextView textView1, textView2, textView3, textView4;

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

    dataHelper = new DataHelper(this);
    textView1 = (TextView) findViewById(R.id.textview1);
    textView2 = (TextView) findViewById(R.id.textview2);
    textView3 = (TextView) findViewById(R.id.textview3);
    textView4 = (TextView) findViewById(R.id.textview4);

    SQLiteDatabase database = dataHelper.getReadableDatabase();
    cursor = database.rawQuery("SELECT * FROM cni_perdu where nom = '" +
            getIntent().getStringExtra("nom") + "'", null);
    cursor.moveToFirst();

    if (cursor.getCount() > 0) {
        cursor.moveToPosition(0);
        textView1.setText(cursor.getString(1));
        textView2.setText(cursor.getString(2));
        textView3.setText(cursor.getString(3));
        textView4.setText(cursor.getString(4));
    }
  }
}

When I execute my app, I have this result

But I want to obtain this result:

Please help me!

edit: excuse me if I duplicate one topic but after a many searching I don't find a positive result. Also excuse me if my English is poor I'm a French-speaking;

Cordially!

---

UPDATE

that is the code of my database

package cm.mavis.easylife;


import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;


public class DataHelper extends SQLiteOpenHelper{
private static final String DATABASE_NAME = "piece_perdu.db";
private static final  int DATABASE_VERSION = 3;
public DataHelper(Context context){
    super(context, DATABASE_NAME,null,DATABASE_VERSION);
}


public void onCreate(SQLiteDatabase database){
    String sql = "create table if not exit cni_perdu(nom text null, prenom text null, ville text null, quartier text null);";
    Log.d("Data", "onCreate: "+sql);
    database.execSQL(sql);
}

@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2){

}
}

Answer 1

 Intent intent = new Intent(getActivity(), LectureInfos.class);
                    intent.putExtra("nom", selection);
                    startActivity(intent);
                    RefreshList();
                    break;

you didnt pass the putExtra Argument Name.

Try

 intent.putExtra("nom", selection);

And in your DBHelper Class

public void onCreate(SQLiteDatabase database){
    String sql = "create table if not exists  cni_perdu(nom text null, prenom text null, ville text null, quartier text null);";
    Log.d("Data", "onCreate: "+sql);
    database.execSQL(sql);
}

Your syntax is wrong .you wrote " exit " instead of " exists "

Answer 2

Change your intent.putExtra("", selection); to intent.putExtra("nom", selection); in FragmentRecherche class

Remember

intent.putExtra() always be in the form of key value pair. If you want to get data from intent you have to use the same key in getIntent().getStringExtra() which you have passed in intent.putExtra()

For Example -:

sending extras with intent from Activity one

Intent intent = new Intent(Main.this, Second.class);
                    intent.putExtra("foo", message);
                    startActivity(intent);

getting extras from intent in Second Activity

String msg  = getIntent().getStringExtra("foo");

Now, Your code must be to your FragmentRecherche

 Intent intent = new Intent(getActivity(), LectureInfos.class);
                    intent.putExtra("nom", selection);
                    startActivity(intent);
                    RefreshList();
                    break;