该程序第一次创建首选项,但之后它永远不会更改它们.我很感激帮助理解为什么.
这是调用xml的PreferencesScreen.
public class PreferencesScreen extends PreferenceFragment{
private final String TAG = "PreferencesScreen";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.d(TAG,"OnCreate");
addPreferencesFromResource(R.xml.prefs);
}
在首选项中,我有一个ListPreference和一个Preference,它调用一个活动来存储电子邮件.
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" >
<PreferenceCategory android:title="Information Collected">
<ListPreference
android:key="loggins"
android:title="Logs Stored"
android:summary="Choose the top kind of logs do you want to store."
android:dialogTitle="Choose Logs"
android:entries="@array/logs"
android:entryValues="@array/logsValues"/>
</PreferenceCategory>
<PreferenceCategory android:title="Email Configurations">
<Preference
android:key="pushing"
android:title="The Email Activity"
android:summary="Just push">
<intent android:action = "ADDING_EMAIL"/>
</Preference>
</PreferenceCategory>
</PreferenceScreen>
一切都在这里.问题出在所谓的……
public class AddingEmail extends ListActivity implements OnClickListener{
private Set<String> emails;
private EditText emailAdd;
SharedPreferences.Editor editor;
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.addingemail);
Button add = (Button) findViewById(R.id.add);
emailAdd = (EditText) findViewById(R.id.email);
prefs = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
editor = prefs.edit();
prefList = toArrayList(prefs.getStringSet("emailWrongs",null));
add.setOnClickListener(this);
}
public void onClick(View v) {
Set<String> list = prefs.getStringSet("emailWrongs",null);
String newEmail = emailAdd.getText().toString();
if (list==null){ //first time the preferences are called.
emails = new TreeSet<String>();
editor.putStringSet("emailWrongs",emails);
editor.apply();
}
if (newEmail != ""){
emails=prefs.getStringSet("emailWrongs",null);
emails.add(newEmail);
editor.putStringSet("emailWrongs",emails);
editor.apply();
}
}
}
关键是它总是存储第一次很好,但如果我在添加另一封电子邮件时,首选项不会改变.他们看起来好像改变了,因为如果我打印它们会显示我添加的所有电子邮件,但偏好文件不会改变(在文件资源管理器中检查它).如果我重新启动或关闭并再次打开,则首选项仅包含我添加的第一封电子邮件.
问题是,如果我回到并更改ListPreference的首选项,那么它甚至存储我添加的电子邮件的所有更改.
希望我很清楚,它有很多代码,因为我想要非常明确.
感谢您的帮助.
解决方法
经过一个多星期的寻找错误,我发现了它.
我认为这对很多遇到同样麻烦的人都有帮助.
我认为这对很多遇到同样麻烦的人都有帮助.
问题是,当我调用首选项来获取字符串集时,它只引用列表而不复制它.因此,我必须创建一个新列表并添加之前存储的所有元素,并添加新元素,然后使用编辑器更改新列表的首选项.
代码是这样的：
Set<String> list = prefs.getStringSet("emailWrongs",null);
Set<String> newList = new TreeSet<String>();
String newEmail = emailAdd.getText().toString();
if (newEmail != ""){
if (list != null){
for(String each: list){
newList.add(each);
}
}
newList.add(newEmail);
editor.putStringSet("emailWrongs",newList);
editor.apply();
}
