在android中，如何在安装应用程序时创建共享首选项？

Question

Hi I'am new to android.
I want to create a shared preferences when the app is first installed and the insert some data.
The shared preference has to be used from all activities in the app.
I tried creating the shared preference in the onCreate() function of the first activity and inserted values into it.And edited the data from another activity.
But when I restart the app the shared preference changes to the data give in the onCreate().
Can somebody help me?

Answer 1

The way if you want to insert data once:

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    SharedPreferences preferences = getSharedPreferences("myPref", MODE_PRIVATE);
    boolean shouldInsertData = preferences.getBoolean("shouldInsertData", true);

    if(shouldInsertData){

        //insert your data into the preferences

        preferences.edit().putBoolean("shouldInsertData", false).apply();

    }

}

Answer 2

Share Preference is best way to store short information. but if you will create share preference from an active, it may create problem to access it from other activity. You should create a global common share preference from application so you can access it through out the android project, any where in any activity. I get reference from here - It is 4 step process.

Step 1 - create a java class file name as "myapp" and extend it by application.

---

public class MyApp extends Application {
private static Context context;
private String TAG ="myApp";
@Override
public void onCreate() {
    super.onCreate();
    context = getApplicationContext();
   // Log.e(TAG, "  myapp stater");
}

public static Context getContext(){
    return context;
}}

Step 2 - in android manifest file inside application tab add android:name=".myapp"

Step 3 - Create java class name as "SharePreferenceUtils" (note don't use name SharePreference.)

---

public class SharePreferenceUtils {

private static String PREFERENCE_NAME = "shopeasy-ecommerce";
private static SharePreferenceUtils sharePreferenceUtils;
private SharedPreferences sharedPreferences;

private SharePreferenceUtils(Context context){
    PREFERENCE_NAME = PREFERENCE_NAME + context.getPackageName();
    this.sharedPreferences = context.getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE);
}

public static SharePreferenceUtils getInstance(){
    if (sharePreferenceUtils == null){
         sharePreferenceUtils = new SharePreferenceUtils(SplashActivity.getContext());
    }
    return sharePreferenceUtils;
}

// login response user_id 1234
public void saveString(String key,  String Val ){
    SharedPreferences.Editor editor = sharedPreferences.edit();
    editor.putString(key, Val);
    editor.commit();
}

public String getString(String key, String defVal){
    return sharedPreferences.getString(key, defVal);
}


public String getString(String key){
    return sharedPreferences.getString(key, "");
}

public void saveInt(String key,  int Val ){
    SharedPreferences.Editor editor = sharedPreferences.edit();
    editor.putInt(key, Val);
    editor.commit();
}

public int getInteger(String key){ return sharedPreferences.getInt(key, 0 ); }

/**
 * Clear all values from this preference
 */
public void clear() {
    SharedPreferences.Editor editor = sharedPreferences.edit();
    editor.clear();
    editor.commit();
}

/**
 * Clear value of given key from this preference
 *
 * @param key name of the key whose value to be removed
 */
public void clearString(String key) {
    SharedPreferences.Editor editor = sharedPreferences.edit();
    editor.remove(key);
    editor.commit();
}}

Step 4 Call sharePreferenceUtil from activity SharePreferenceUtils.getInstance().saveString("Username", "username value here");

Now you can access sharepreference from any activity. Just call instance of sharepreference java class.