Shared preferences in Android doesn't save when i switch activity or close app

问题

I checked similar questionsions and noting seems to work. I can't figure out what seems to be the problem. Value goes to 0 after every app restart or activity switch.

//just parts of code from activity1
            SharedPreferences pref;
            SharedPreferences.Editor editor;
// On create....
            pref = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
            editor = pref.edit();
            max=pref.getInt("mxtime", 0);

//If something>something...
            editor.putInt("mxtime", max);
            editor.commit();

In the first part i declare SharedPreferences in main Activity. I save it in "max" int and its always 0 on startup since if empty value is 0. On second activity I have a button, where on click it should empty the value from SharedPreferences.

Activity 2:

public class settings extends AppCompatActivity {
private Button myButton;
private Button myButton2;
private Button myButton3;
//sharedPrefs
SharedPreferences pref;
SharedPreferences.Editor editor;

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

    pref = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
    editor = pref.edit();
    myButton = (Button) findViewById(R.id.button3);
    myButton2 = (Button) findViewById(R.id.button4);
    myButton3 = (Button) findViewById(R.id.button5);

    myButton.setOnClickListener(new View.OnClickListener(){
        public void onClick(View v) {
            Intent i = new Intent(getApplicationContext(),MainActivity.class);
            startActivity(i);


        }
    });
    myButton2.setOnClickListener(new View.OnClickListener(){
        public void onClick(View v) {
            //sharedPrefs
            editor.remove("mxtime");
            editor.commit();


        }
    });
}

}

回答1:

Try to use SharedPreferences like this:

 SharedPreferences preferences = getApplicationContext().getSharedPreferences("loginPref", MODE_PRIVATE);
 SharedPreferences.Editor editor = preferences.edit();

回答2:

Activity 1:

SharedPreferences sp = getSharedPreferences("YourSharedPreference", Activity.MODE_PRIVATE);
SharedPreferences.Editor editor = sp.edit();
int DEFAULT_VALUE = 0;
editor.putInt("VARIABLE_KEY", DEFAULT_VALUE);

//If something > something..

int VALUE_TO_PASS = <your value here>;
editor.putInt("VARIABLE_KEY", VALUE_TO_PASS);

// Before screen shift

editor.commit();

...........................................

Activity 2:

SharedPreferences sp = getSharedPreferences("YourSharedPreference", Activity.MODE_PRIVATE);
int DEFAULT_FALLBACK_VALUE = 0;  //When value is not received, show this

int VALUE_PASSED = sp.getInt("VARIABLE_KEY", DEFAULT_FALLBACK_VALUE);

// On button click:

int DEFAULT_VALUE = 0;
editor.putInt("VARIABLE_KEY", DEFAULT_VALUE);
editor.commit();

来源：https://stackoverflow.com/questions/36541997/shared-preferences-in-android-doesnt-save-when-i-switch-activity-or-close-app

标签

java

android

android-sharedpreferences