Question

我正在尝试制作一个像游戏一样的世界创造者的东西，我正在使用共享偏好来存储阵列等。但有一个问题。我试图从另一个类更新它，所以我使用静态变量来做到这一点。但是当我使用列表视图返回原始类时，我发现没有更新任何内容。有任何想法吗？这是代码。哦，logcat没有出错。

ListView类。

package you.don't.need-to-know;

import android.app.ListActivity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;


public class WorldMenu extends  ListActivity{
public static SharedPreferences prefs = null;
static String splitter;
String[] worldList;
@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    prefs = PreferenceManager.getDefaultSharedPreferences(this);
    splitter =  "Create World," + prefs.getString("worldString", "");
    worldList = splitter.split(",");
    setListAdapter(new ArrayAdapter<String>(WorldMenu.this,
    android.R.layout.simple_list_item_1, worldList));


}
@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
    // TODO Auto-generated method stub
    super.onListItemClick(l, v, position, id);
    if(position == 0){
        Intent openWorldNamer = new                                           
 Intent("you.don't.need-to-know");
        startActivity(openWorldNamer);
    }

}


}

更新程序：

package you.don't.need-to-know;

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

public class WorldCreator extends Activity{
EditText worldNameEditor;
Button saver;
static String updater;
@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_worldcreator);
    worldNameEditor = (EditText) findViewById(R.id.editText1);
    saver = (Button) findViewById(R.id.button1);
    updater = worldNameEditor.getText().toString() + ",";
    saver.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            Editor editor = WorldMenu.prefs.edit();
            editor.putString("worldString", updater);
            editor.commit();
            Intent openListWorld = new
 Intent("you.don't.need.to-know");
            startActivity(openListWorld);
        }
    });
}
@Override
protected void onPause() {
    // TODO Auto-generated method stub
    super.onPause();

}

}

编辑：新代码更新，更接近修复。更新程序和列表活动

更新

 import android.app.Activity;

 import android.content.Intent;

 import android.content.SharedPreferences;

 import android.content.SharedPreferences.Editor;

 import android.content.SharedPreferences.OnSharedPreferenceChangeListener;

 import android.os.Bundle;

 import android.preference.PreferenceManager;

 import android.view.View;

 import android.widget.Button;

 import android.widget.EditText;


public class WorldCreator extends Activity{
EditText worldNameEditor;
Button saver;
SharedPreferences prefs;
OnSharedPreferenceChangeListener listener;
String updater;
Editor editor;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_worldcreator);
    prefs = PreferenceManager.getDefaultSharedPreferences(this);
    worldNameEditor = (EditText) findViewById(R.id.hello);
    saver = (Button) findViewById(R.id.button1);
    updater = worldNameEditor.getText().toString() + ",";

saver.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        listener = new SharedPreferences.OnSharedPreferenceChangeListener()  
{
            public void onSharedPreferenceChanged(SharedPreferences      
  prefs, String key) {
                editor = prefs.edit();
                editor.putString("worldString", updater);   
                editor.commit();
              }
            };

            prefs.registerOnSharedPreferenceChangeListener(listener);
            Intent openListWorld = new                                    
 Intent("");
            startActivity(openListWorld);

    }});

    }
    @Override
    protected void onPause() {
        // TODO Auto-generated method stub
        super.onPause();





    }





@Override
protected void onResume() {
    // TODO Auto-generated method stub
    super.onResume();

}
}

列出活动：

import android.app.ListActivity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;


public class WorldMenu extends  ListActivity{
SharedPreferences prefs = null;
String splitter;
String[] worldList;
@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);

}

@Override
protected void onResume() {
    // TODO Auto-generated method stub
    super.onResume();
    prefs = PreferenceManager.getDefaultSharedPreferences(this);
    splitter =  "Create World," + prefs.getString("worldString", "hello");
    worldList = splitter.split(",");
    setListAdapter(new ArrayAdapter<String>(WorldMenu.this,          
 android.R.layout.simple_list_item_1, worldList));
}

@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
    // TODO Auto-generated method stub
    super.onListItemClick(l, v, position, id);
    if(position == 0){
        Intent openWorldNamer = new                                          
Intent("");
        startActivity(openWorldNamer);
    }

}

@Override
protected void onPause() {
    // TODO Auto-generated method stub
    super.onPause();
    finish();
}


}

Answer 1

看起来您不会监视共享首选项中的更改。见：

http://developer.android.com/reference/android/content/SharedPreferences.OnSharedPreferenceChangeListener.html

final SharedPreferences.OnSharedPreferenceChangeListener listener = new SharedPreferences.OnSharedPreferenceChangeListener() {
public void onSharedPreferenceChanged(SharedPreferences prefs, String key) {
    // update your listview.
  }
};

prefs.registerOnSharedPreferenceChangeListener(listener);

所以当你得到那个回调时，它会告诉你改变了哪个键。然后，您可以更新listview的适配器以获取新内容并在适配器中调用onDataSetChanged（）。

或者，您可以将适配器设置代码移动到onResume（）函数中。这将使您的活动恢复时，您检查共享首选项的状态并设置适配器。但是请注意，如果用户向下滚动列表一段距离并且您在简历中再次调用setAdapter（），它们将丢失其滚动位置。

编辑：

尝试：

更新程序（这不需要启动新活动，这可以完成（））：

import android.app.Activity;

 import android.content.Intent;

 import android.content.SharedPreferences;

 import android.content.SharedPreferences.Editor;

 import android.content.SharedPreferences.OnSharedPreferenceChangeListener;

 import android.os.Bundle;

 import android.preference.PreferenceManager;

 import android.view.View;

 import android.widget.Button;

 import android.widget.EditText;


public class WorldCreator extends Activity{
EditText worldNameEditor;
Button saver;
SharedPreferences prefs;
OnSharedPreferenceChangeListener listener;
String updater;
Editor editor;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_worldcreator);
    prefs = PreferenceManager.getDefaultSharedPreferences(this);
    worldNameEditor = (EditText) findViewById(R.id.hello);
    saver = (Button) findViewById(R.id.button1);
    updater = worldNameEditor.getText().toString() + ",";

saver.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
           editor = prefs.edit();
           editor.putString("worldString", updater);   
           editor.commit();
           finish();
    }});

    }

的ListView：

import android.app.ListActivity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;


public class WorldMenu extends  ListActivity{
SharedPreferences prefs = null;
String splitter;
String[] worldList;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    prefs = PreferenceManager.getDefaultSharedPreferences(this);
final SharedPreferences.OnSharedPreferenceChangeListener listener = new SharedPreferences.OnSharedPreferenceChangeListener() {
public void onSharedPreferenceChanged(SharedPreferences prefs, String key) {
    // update your listview.
  }
};

prefs.registerOnSharedPreferenceChangeListener(listener);

}

@Override
protected void onResume() {
    // TODO Auto-generated method stub
    super.onResume();

    splitter =  "Create World," + prefs.getString("worldString", "hello");
    worldList = splitter.split(",");
    setListAdapter(new ArrayAdapter<String>(WorldMenu.this,          
 android.R.layout.simple_list_item_1, worldList));
}

@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
    // TODO Auto-generated method stub
    super.onListItemClick(l, v, position, id);
    if(position == 0){
        Intent openWorldNamer = new                                          
Intent("");
        startActivity(openWorldNamer);
    }

}
}

Answer 2

Prefrences在活动级别定义。我会得到我的赏金。

调用getActivity（）以获取调用者活动，然后使用它来获取prefrences。如果您希望结构通过接口发回结果。实现界面并使用界面查找活动。 Eclipse会为您创建存根。

这是完整的类，只更改prefrence save，并立即将结果发送回调用类。它使用getActivity（），因此这两个类共享相同的prefrence。它通过接口回调。

来自我的应用程序com.gosylvester.bestrides

    package com.gosylvester.bestrides;

import com.google.android.gms.maps.GoogleMap;

import android.support.v4.app.DialogFragment;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.RadioGroup.OnCheckedChangeListener;
import android.content.Context;
import android.content.SharedPreferences;
import android.os.Bundle;

//...

public class MapSettings extends DialogFragment implements

    OnCheckedChangeListener {

public static final String MAP_TYPE = "com.gosylvester.bestrides.settings.maptype";
private int _mapType = -1;
BestRidesSettingsDialogListener activity;
SharedPreferences sharedpref;

public interface BestRidesSettingsDialogListener {
    void onMapSettingsChange(int mapType);
}

public MapSettings() {
}

@Override
public void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

    // the activity may be null if this is called without implementing the
    // BestRidesSettingsDialogListener (The settings object saves the
    // setting so the
    // call back may not be needed.

    activity = (BestRidesSettingsDialogListener) getActivity();

    getDialog().setTitle(R.string.app_name);
    View view = inflater.inflate(R.layout.activity_map_settings, container);
    RadioGroup rg = (RadioGroup) view.findViewById(R.id.radioGroup1);
    // initialize to the shared preferences value
    rg.clearCheck();
    sharedpref = getActivity().getPreferences(Context.MODE_PRIVATE);
    int x = sharedpref.getInt(MAP_TYPE, GoogleMap.MAP_TYPE_NORMAL);
    RadioButton rb = null;

    switch (x) {
    case GoogleMap.MAP_TYPE_HYBRID:
        rb = (RadioButton) view.findViewById(R.id.RDOHybrid);
        rb.setChecked(true);
        break;
    case GoogleMap.MAP_TYPE_NORMAL:
        rb = (RadioButton) view.findViewById(R.id.RDORoad);
        rb.setChecked(true);
        break;
    case GoogleMap.MAP_TYPE_SATELLITE:
        rb = (RadioButton) view.findViewById(R.id.RDOSatelite);
        rb.setChecked(true);
        break;
    case GoogleMap.MAP_TYPE_TERRAIN:
        rb = (RadioButton) view.findViewById(R.id.RDOTerrain);
        rb.setChecked(true);
        break;
    }
    // set the listener after setting up
    rg.setOnCheckedChangeListener(this);
    return view;
}

public int getMapType() {
    return _mapType;
}

public void setMapType(int mapType) {
    this._mapType = mapType;
}

@Override
public void onCheckedChanged(RadioGroup rg, int checkId) {
    // TODO Auto-generated method stub
    int mapType = 0;
    switch (checkId) {
    case R.id.RDORoad:
        mapType = GoogleMap.MAP_TYPE_NORMAL;
        break;
    case R.id.RDOHybrid:
        mapType = GoogleMap.MAP_TYPE_HYBRID;
        break;
    case R.id.RDOSatelite:
        mapType = GoogleMap.MAP_TYPE_SATELLITE;
        break;
    case R.id.RDOTerrain:
        mapType = GoogleMap.MAP_TYPE_TERRAIN;
        break;
    }
    // run the activity onchange
    // if the activity is null there is no listener to take action on the
    // settings
    if (activity != null) {
        activity.onMapSettingsChange(mapType);
    }

    // save the settings
    if (sharedpref == null) {
        sharedpref = getActivity().getPreferences(Context.MODE_PRIVATE);
    }
    sharedpref.edit().putInt(MAP_TYPE, mapType).commit();
}

}

/ *这是另一个类* /

的snipet

public class KmlReader extends FragmentActivity implements
        BestRidesSettingsDialogListener {

...

mMap.setMapType(sharedPref.getInt(
                com.gosylvester.bestrides.MapSettings.MAP_TYPE,
                GoogleMap.MAP_TYPE_NORMAL));

...

@Override
public void onMapSettingsChange(int mapType) {
    // TODO Auto-generated method stub
    if (mMap != null) {
        mMap.setMapType(mapType);
    }
}

祝你好运

Answer 3

如果所有类都在同一个进程中，则共享首选项应用于多个类。您不必明确地使用静态。只需在两个类中使用相同的共享首选项。

Answer 4

当你回到原来的类时，它不保证onCreate mothod的原始类可以执行，就像其他答案所说，你可以将代码放入onResume方法，或者在startActivity（intent）之后添加方法finish（）完成当前活动

共享首选项不会更新

4 个答案: