Android 中的共享首选项在我切换 activity 或关闭应用程序时未保存

Question

我检查了类似的问题并指出似乎有效。我无法弄清楚似乎是什么问题。每次应用重新启动或 activity 切换后，值变为 0。

//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();

在第一部分中，我在主 Activity 中声明了 SharedPreferences。我将它保存在 "max" int 中，它在启动时始终为 0，因为如果空值为 0。在第二个 activity 我有一个按钮，点击它应该清空 SharedPreferences 中的值。

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();


        }
    });
}

}

Answer 1

尝试像这样使用 SharedPreferences：

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

Answer 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();

Android 中的共享首选项在我切换 activity 或关闭应用程序时未保存

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

java

android

android-sharedpreferences