无法使用“共享首选项”存储数据

Question

即使我从应用程序退出，我希望应用程序存储数据。这就是我希望我的应用程序如何工作的方式。假设有3个活动，Main，A，B和C.主要用于显示，A是编辑值的菜单，B和C是编辑界面。在转到B进行编辑之后，它将返回到A，如果我去C编辑其他内容，我的B数据将不会进行任何更改。但我无法做到，我面临的问题是它总是自动删除其他数据。请帮助，谢谢。

主

package com.example.suntracking;
import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends Activity implements View.OnClickListener{

TextView aziangle,elevation,numberof,rightasc,decli,hourangle,solartime,showinlat,showinlong;
Button editting;
Long latval,longval;
String show1,show2;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    initialize();
    loadSavedpreferences();
}




private void loadSavedpreferences() {
    // TODO Auto-generated method stub
    SharedPreferences savedata=PreferenceManager.getDefaultSharedPreferences(this);
    show1=savedata.getString("show1",null);
    latval=savedata.getLong("latitudevalue", 0);
    showinlat.setText("Latitude is : " + latval + ", " + show1);
}




private void initialize() {
    // TODO Auto-generated method stub
    aziangle=(TextView)findViewById(R.id.tvAziAngle);
    elevation=(TextView)findViewById(R.id.tvElevation);
    numberof=(TextView)findViewById(R.id.tvNumberof);
    rightasc=(TextView)findViewById(R.id.tvRightAsc);
    decli=(TextView)findViewById(R.id.tvDecli);
    hourangle=(TextView)findViewById(R.id.tvHourAngle);
    solartime=(TextView)findViewById(R.id.tvSolarTime);
    showinlat=(TextView)findViewById(R.id.tvShowInLat);
    showinlong=(TextView)findViewById(R.id.tvShowInLong);
    editting=(Button)findViewById(R.id.bedit);
    editting.setOnClickListener(this);
    }

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public void onClick(View v) {
    // TODO Auto-generated method stub
    Intent e=new Intent(MainActivity.this, Parameterlist.class);
    savePreferences("show1",show1);
    savePreferences("latval",latval);
    startActivityForResult(e,0);
}


private void savePreferences(String string, Long latval2) {
    // TODO Auto-generated method stub
       SharedPreferences savedata = getApplicationContext().getSharedPreferences(
               "savealldata", MODE_PRIVATE);
    Editor editor=savedata.edit();
    editor.putLong("latval", latval);
    editor.commit();
}




private void savePreferences(String string, String show1) {
    // TODO Auto-generated method stub
       SharedPreferences savedata = getApplicationContext().getSharedPreferences(
               "savealldata", MODE_PRIVATE);
    Editor editor=savedata.edit();
    editor.putString("show1", show1);
    editor.commit();
}




@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    // TODO Auto-generated method stub
    super.onActivityResult(requestCode, resultCode, data);
    if(resultCode==RESULT_OK){
    loadSavedpreferences();
    Bundle getanswer=data.getExtras();
    show1=getanswer.getString("showloc1");
    latval=getanswer.getLong("anslatitudevalue");
    showinlat.setText("Latitude is : " + latval + ", " + show1);
    show2=getanswer.getString("longiloc");
    longval=getanswer.getLong("anslongitudevalue");
    showinlong.setText("Latitude is : " + longval + ", " + show2);
    savePreferences("show1",show1);
    savePreferences("latval",latval);
    }
}

} 菜单

    package com.example.suntracking;
    import android.app.Activity;
    import android.app.ListActivity;
    import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class Parameterlist extends ListActivity{


    String selection[]={"Latitude","Longitude","TimeZone","DaylightSavingTime","OffsetParameters"};

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setListAdapter(new ArrayAdapter<String>(Parameterlist.this, android.R.layout.simple_list_item_1, selection));

    }
    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        // TODO Auto-generated method stub
        super.onListItemClick(l, v, position, id);
        String choosen= selection[position];
        try{
            Class ourclass = Class.forName("com.example.suntracking." + choosen);
            Intent ourintent=new Intent(Parameterlist.this,ourclass);
            startActivityForResult(ourintent,0);
        }catch(ClassNotFoundException e){
            e.printStackTrace();
        }
    }
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        // TODO Auto-generated method stub
        super.onActivityResult(requestCode, resultCode, data);
        if(resultCode==RESULT_OK){
            Bundle ans=data.getExtras();
            Intent ansall=new Intent();
            ansall.putExtras(ans);
            setResult(RESULT_OK,ansall);
            finish();
        }

    }


}

活动B

    package com.example.suntracking;

import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioGroup;
import android.widget.RadioGroup.OnCheckedChangeListener;

public class Latitude extends Activity implements OnClickListener,OnCheckedChangeListener{

    EditText latitudein;
    Button savelatitude;
    RadioGroup nschoose;
    String latitudeloc,temp;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.latitude);
        initialize();

    }

    private void initialize() {
        // TODO Auto-generated method stub
        latitudein=(EditText)findViewById(R.id.etLatitude);
        savelatitude=(Button)findViewById(R.id.bSaveLatitude);
        nschoose=(RadioGroup)findViewById(R.id.rgChoicelatitude);
        savelatitude.setOnClickListener(this);
        nschoose.setOnCheckedChangeListener(this);
    }

    @Override
    public void onCheckedChanged(RadioGroup arg0, int arg1) {
        // TODO Auto-generated method stub
        switch(arg1){
        case R.id.rbNorth:
            latitudeloc="North";
            break;
        case R.id.rbSouth:
            latitudeloc="South";
            break;
        }

    }

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        temp = latitudein.getText().toString();
        try{
            Intent backtomain1=new Intent();
            Bundle answerlat=new Bundle();
            answerlat.putString("showloc1", latitudeloc);
            Long intlatitudevalue=Long.parseLong(temp);
            answerlat.putLong("anslatitudevalue", intlatitudevalue);
            backtomain1.putExtras(answerlat);
            setResult(RESULT_OK,backtomain1);
            finish();
        }catch (NumberFormatException e){
            e.printStackTrace();
        }


    }

}

活动C

    package com.example.suntracking;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioGroup;
import android.widget.RadioGroup.OnCheckedChangeListener;

public class Longitude extends Activity implements OnClickListener,OnCheckedChangeListener{

    EditText longitudein;
    RadioGroup longitudechoice;
    Button savelongitude;
    String longitudeloc,temp;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.longitude);
        initialize();
    }

    private void initialize() {
        // TODO Auto-generated method stub
        longitudein=(EditText)findViewById(R.id.etLongitude);
        longitudechoice=(RadioGroup)findViewById(R.id.rgChoicelongitude);
        savelongitude=(Button)findViewById(R.id.bSaveLongitude);
        savelongitude.setOnClickListener(this);
        longitudechoice.setOnCheckedChangeListener(this);

    }

    @Override
    public void onCheckedChanged(RadioGroup group, int checkedId) {
        // TODO Auto-generated method stub
        switch(checkedId){
        case R.id.rbEast:
            longitudeloc="East";
            break;
        case R.id.rbWest:
            longitudeloc="West";
            break;
        }
    }

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        temp = longitudein.getText().toString();
        try{
            Bundle anslong=new Bundle();
            anslong.putString("longiloc", longitudeloc);
            Long intlongitudevalue=Long.parseLong(temp);
            anslong.putLong("anslongitudevalue", intlongitudevalue);
            Intent backtomain2=new Intent();
            backtomain2.putExtras(anslong);
            setResult(RESULT_OK,backtomain2);
            finish();
        }catch (NumberFormatException e){
            e.printStackTrace();
        }
    }

}

---

我尝试通过使用SharedPreferences使其变得简单。这是代码。现在我有另一个问题是它保存了初始数据，但即使我输入新数据也不会做任何更改。所以我认为我没有在mainactivity中取出它，我该怎么做才能将它从SharedPreferences中取出来。

主要

   package com.example.suntracking;

import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends Activity implements View.OnClickListener{

    TextView aziangle,elevation,numberof,rightasc,decli,hourangle,solartime,showinlat,showinlong;
    Button editting;
    Long latval,longval;
    String show1,show2;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initialize();
        loadSavedpreferences();
    }




    private void loadSavedpreferences() {
        // TODO Auto-generated method stub
        SharedPreferences savedata= getSharedPreferences("savealldata",0);
        show1=savedata.getString("show1",null);
        latval=savedata.getLong("latval", 0);
        showinlat.setText("Latitude is : " + latval + ", " + show1);
    }




    private void initialize() {
        // TODO Auto-generated method stub
        aziangle=(TextView)findViewById(R.id.tvAziAngle);
        elevation=(TextView)findViewById(R.id.tvElevation);
        numberof=(TextView)findViewById(R.id.tvNumberof);
        rightasc=(TextView)findViewById(R.id.tvRightAsc);
        decli=(TextView)findViewById(R.id.tvDecli);
        hourangle=(TextView)findViewById(R.id.tvHourAngle);
        solartime=(TextView)findViewById(R.id.tvSolarTime);
        showinlat=(TextView)findViewById(R.id.tvShowInLat);
        showinlong=(TextView)findViewById(R.id.tvShowInLong);
        editting=(Button)findViewById(R.id.bedit);
        editting.setOnClickListener(this);
        }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        savePreferences();
        Intent e=new Intent(MainActivity.this, Parameterlist.class);
        savePreferences();
        startActivity(e);
    }


    private void savePreferences() {
        // TODO Auto-generated method stub
        SharedPreferences savedata = getSharedPreferences("savealldata",0);
        Editor editor=savedata.edit();
        editor.putLong("latval", latval);
        editor.putString("show1", show1);
        editor.commit();
    }

菜单

    package com.example.suntracking;

import android.app.Activity;
import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class Parameterlist extends ListActivity{


    String selection[]={"Latitude","Longitude","TimeZone","DaylightSavingTime","OffsetParameters"};

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setListAdapter(new ArrayAdapter<String>(Parameterlist.this, android.R.layout.simple_list_item_1, selection));

    }
    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        // TODO Auto-generated method stub
        super.onListItemClick(l, v, position, id);
        String choosen= selection[position];
        try{
            Class ourclass = Class.forName("com.example.suntracking." + choosen);
            Intent ourintent=new Intent(Parameterlist.this,ourclass);
            startActivity(ourintent);
            finish();
        }catch(ClassNotFoundException e){
            e.printStackTrace();
        }
    }

ACT B

    package com.example.suntracking;

import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioGroup;
import android.widget.RadioGroup.OnCheckedChangeListener;

public class Latitude extends Activity implements OnClickListener,OnCheckedChangeListener{

    EditText latitudein;
    Button savelatitude;
    RadioGroup nschoose;
    String latitudeloc,temp;
    Long intlatitudevalue;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.latitude);
        initialize();

    }

    private void initialize() {
        // TODO Auto-generated method stub
        latitudein=(EditText)findViewById(R.id.etLatitude);
        savelatitude=(Button)findViewById(R.id.bSaveLatitude);
        nschoose=(RadioGroup)findViewById(R.id.rgChoicelatitude);
        savelatitude.setOnClickListener(this);
        nschoose.setOnCheckedChangeListener(this);
    }

    @Override
    public void onCheckedChanged(RadioGroup arg0, int arg1) {
        // TODO Auto-generated method stub
        switch(arg1){
        case R.id.rbNorth:
            latitudeloc="North";
            break;
        case R.id.rbSouth:
            latitudeloc="South";
            break;
        }

    }

    @Override
    public void onClick(View v) {
        temp = latitudein.getText().toString();
        try{
        intlatitudevalue=Long.parseLong(temp);
    savePreferences();
            finish();
        }catch (NumberFormatException e){
            e.printStackTrace();
        }


    }

    private void savePreferences() {
        // TODO Auto-generated method stub
        SharedPreferences savedata = getSharedPreferences("savealldata",0);
        Editor editor=savedata.edit();
        editor.putLong("latval", intlatitudevalue);
        editor.putString("show1", latitudeloc);
        editor.commit();
    }

编辑：我通过强制重启应用程序找到了解决方案。任何其他方法??

Answer 1

问题在于PreferenceManager.getDefaultSharedPreferences(...)的召唤。

特别是，您将通过调用检索SharedPreferences对象，该对象未命名为“savealldata”，但名为[$YourPackageName]_preferences。

因此，您应该使用相同的名称确保SharedPreferences。

参见：$ android-sdk \ sources \ android-18 \ android \ preference \ PreferenceManager.java