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我已经有这个问题好几天了。当我设置我的数据时，我的共享偏好似乎不起作用。用户从main开始，显示“oncreate”，然后进入设置页面（自动设置数据的地方（暂时）），当他们返回主Activity时，数据似乎不想过来. 我正在使用 joda Time 库，并且正在尝试计算两个日期之间的时间差。

Main：（onCreate代码和onResume代码相同）

public class MainActivity extends Activity {

    TextView tv; 
    Button set;

    //CONST
    final static long MILLIS_IN_DAY = 86400000;
    final static long MILLIS_IN_HOUR = 3600000;
    final static long MILLIS_IN_MINUTE = 60000;
    long day, hour, minute;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tv = (TextView) findViewById(R.id.textViewx);
        set = (Button) findViewById(R.id.setting);
        tv.setText("ONCREATE!");

        //LOAD DATA
        SharedPreferences prefs = getPreferences(MODE_PRIVATE);
        long loadedTime = prefs.getLong("quitDate", 0); //Load Settings Data
        boolean test = prefs.getBoolean("test", false);

        //get Comparison Data
        DateTime newDate = new DateTime();
        long updateTime = newDate.getMillis();
        long diffInMillis =  (updateTime-loadedTime);

        //Calculate
        minute = (diffInMillis/MILLIS_IN_MINUTE)%60;
        hour = (diffInMillis/MILLIS_IN_HOUR)%24;
        day = (diffInMillis/MILLIS_IN_DAY);

        tv.setText(""+Long.toString(loadedTime));
        if(test==true){
            tv.setText("" + "\nDay|Hour|Minute: " + Long.toString(day) +":" + Long.toString(hour) + ":" + Long.toString(minute));   
        }


        set.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                Intent x = new Intent(MainActivity.this, Settings.class);
                startActivity(x);

            }
        });

设置：

import org.joda.time.DateTime;
import android.content.SharedPreferences;

public class Settings extends Activity implements View.OnClickListener {
    Button bAbout,bSettings,bFacebook;
    //(5000);
            final long MILLIS_IN_DAY = 86400000;
            final long MILLIS_IN_HOUR = 3600000;
            final long MILLIS_IN_MINUTE = 60000;
    //Variables
    long loadedTime;
    int packs;
    float cost;
    long day, hour, minute, second;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setTitle("Settings");
        setContentView(R.layout.activity_settings);
        setUpButtons();

        DateTime d1 = new DateTime(2013,9,11,0,0);

        long today = d1.getMillis();        

        //SAVE DATA
        SharedPreferences.Editor editor = getPreferences(MODE_PRIVATE).edit();
         editor.putLong("quitDate", today);
         editor.putBoolean("test", true);
         editor.commit();

        minute = (today/MILLIS_IN_MINUTE)%60;
        hour = (today/MILLIS_IN_HOUR)%24;
        day = (today/MILLIS_IN_DAY);

        TextView tv = (TextView) findViewById(R.id.TEMPDATE);
        TextView tv2 = (TextView) findViewById(R.id.todayis);
    tv2.setText("Today is: " + Long.toString(today));

    }
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1 回答 1

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您正在使用每个活动专用的首选项。这意味着您有两组首选项：一组用于 MainActivity，一组用于设置。

这是相关的文档片段：

Activity 持久状态通过 getPreferences(int) 方法进行管理，允许您检索和修改与 Activity 关联的一组名称/值对。要使用跨多个应用程序组件（活动、接收器、服务、提供者）共享的首选项，您可以使用底层 Context.getSharedPreferences() 方法来检索存储在特定名称下的首选项对象

http://developer.android.com/reference/android/app/Activity.html#getPreferences(int)

您可以使用类似的东西getSharedPreferences("MY_PREFERENCES", MODE_PRIVATE)或只是调用PreferenceManager.getDefaultSharedPreferences(Context context)来获取默认的共享首选项集。

于 2013-09-12T19:34:37.173 回答