Kann nicht in der Lage sharedpreference

Question

hier mit Favoritenliste hinzufügen wird der Fehler

Prozess: com.example.sonu.travelfreak, PID: 15374 java.lang.NullPointerException bei com.example.sonu. travelfreak.PlaceView $ 1.onClick (PlaceView.java:42) bei android.view.View.performClick (View.java:4438) bei android.widget.CompoundButton.performClick (CompoundButton.java:100) bei android.view .View $ PerformClick.run (View.java:18422) bei android.os.Handler .handleCallback (Handler.java:733) bei android.os.Handler.dispatchMessage (Handler.java:95) bei android.os.Looper.loop (Looper.java:136) bei android.app.ActivityThread.main (ActivityThread.java:5001) bei java.lang.reflect.Method.invokeNative (native Methode) bei java.lang.reflect.Method.invoke (Method.java:515) bei com.android.internal.os. ZygoteInit $ MethodAndArgsCaller.run (ZygoteInit.java:785) bei com.android.internal.os.ZygoteInit.main (ZygoteInit.java:601) bei dalvik.system.NativeStart.main (native Methode)

Klasse, die

Favoriten hinzufügen

public class PlaceView extends AppCompatActivity{ 
TextView textView1; 
TextView textView2; 
ToggleButton toggleButton; 
SharedPreference sharedPreference; 
@Override 
protected void onCreate(final Bundle savedInstanceState) { 

    super.onCreate(savedInstanceState); 
    setContentView(R.layout.place_view); 

    textView1= (TextView) findViewById(R.id.textViewActivity); 
    textView2= (TextView) findViewById(R.id.detail); 
    Intent intent=getIntent(); 
    final Bundle bundle=intent.getExtras(); 
    textView1.setText(bundle.getString("Activity")); 
    textView2.setText(bundle.getString("Detail")); 
    toggleButton= (ToggleButton) findViewById(R.id.toggleButton1); 

    toggleButton.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      if(toggleButton.isChecked()){ 
       Log.d("check",bundle.getString("position name")); 
       Toast.makeText(getApplicationContext(), 
         "Added as favorites", 
         Toast.LENGTH_SHORT).show(); 
       sharedPreference.addFavorite(getApplicationContext(),bundle.getString("position name")); 

     } 
      else{ 

       } 

      } 


    }); 

} 

}

Klasse, die

public class fav_info { 
String string; 
public String getname(){ 
    return string; 
} 
public void setname(String name){ 
    this.string=name; 
}} 

sharedpreference Klasse für jede Zeile von recyclerview Wert gesetzt, fügen Sie handhaben, entfernen, speichern Favoriten

import android.content.Context; 
import android.content.SharedPreferences; 
import android.content.SharedPreferences.Editor; 
import com.google.gson.Gson; 
import java.util.ArrayList; 
import java.util.Arrays; 
import java.util.List; 
public class SharedPreference { 
public static final String PREFS_NAME = "PRODUCT_APP"; 
public static final String FAVORITES = "Product_Favorite"; 

public SharedPreference() { 
    super(); 
} 


public void saveFavorites(Context context, List<fav_info> favorites) { 
    SharedPreferences settings; 
    Editor editor; 

    settings = context.getSharedPreferences(PREFS_NAME, 
      Context.MODE_PRIVATE); 
    editor = settings.edit(); 

    Gson gson = new Gson(); 
    String jsonFavorites = gson.toJson(favorites); 

    editor.putString(FAVORITES, jsonFavorites); 

    editor.commit(); 
} 

public void addFavorite(Context context, String string) { 
    fav_info fi=new fav_info(); 
    fi.setname(string); 
    List<fav_info> favorites = getFavorites(context); 
    if (favorites == null) 
     favorites = new ArrayList<fav_info>(); 
    favorites.add(fi); 
    saveFavorites(context, favorites); 
} 

public void removeFavorite(Context context, fav_info fav_info) { 
    ArrayList<fav_info> favorites = getFavorites(context); 
    if (favorites != null) { 
     favorites.remove(fav_info); 
     saveFavorites(context, favorites); 
    } 
} 

public ArrayList<fav_info> getFavorites(Context context) { 
    SharedPreferences settings; 
    List<fav_info> favorites; 

    settings = context.getSharedPreferences(PREFS_NAME, 
      Context.MODE_PRIVATE); 

    if (settings.contains(FAVORITES)) { 
     String jsonFavorites = settings.getString(FAVORITES, null); 
     Gson gson = new Gson(); 
     fav_info[] favoriteItems = gson.fromJson(jsonFavorites, 
       fav_info[].class); 

     favorites = Arrays.asList(favoriteItems); 
     favorites = new ArrayList<fav_info>(favorites); 
    } else 
     return null; 

    return (ArrayList<fav_info>) favorites; 
}} 

Answer 1

Sie haben die SharedPreference Klasse instanziiert, bevor Sie es

so diese Zeile hinzufügen, bevor Zugriff auf sharedPreference Objekt,

SharedPreference sharedPreference = new SharedPreference(); 

Objekt ist Ich glaube, Sie diese Zeile hinzufügen vergessen ..

Hinweis: in Ihrem Code Sie SharedPreference als Klassenattribut deklariert haben, so würde folgende Zeile in Ordnung sein,

sharedPreference = new SharedPreference(); 

Dank