我有一个偏好活动,该活动的language
为ListPreference
,显示可用的语言列表。我可以在调用onCreate时填充列表,但是我想在用户单击它时填充列表。
this is the java code
:
public class SettingsActivity extends PreferenceActivity implements OnPreferenceClickListener {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
try {
addPreferencesFromResource(R.xml.settings);
} catch (Exception e) {
}
}
@Override
public boolean onPreferenceClick(Preference preference) {
if((preference instanceof ListPreference) && (preference.getKey().equals("language"))){
ListPreference lp = (ListPreference)preference;
CharSequence[] entries = { "English", "French" };
CharSequence[] entryValues = {"1" , "2"};
lp.setEntries(entries);
lp.setDefaultValue("1");
lp.setEntryValues(entryValues);
return true;
}
return false;
}
}
这是settings.xml
(首选项):
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen
xmlns:android="http://schemas.android.com/apk/res/android">
<PreferenceCategory android:title="General Settings">
<CheckBoxPreference android:key="enabled" android:title="Application Status" android:summary="Enable or disable the application" />
<ListPreference
android:key="language"
android:title="Language"
android:dialogTitle="Application language"
android:summary="Select the Application language"
/>
</PreferenceCategory>
</PreferenceScreen>
我搜索了但没有找到结果!每当我单击该列表时,都会发生异常。
由于出现异常,因为未初始化ListPreference对象-您需要在XML中设置entries
和entryValues
属性,或者在onCreate()
中以编程方式进行设置。
如果初始化初始ListPreference对象后,如果需要动态更改列表中的项目,则需要将OnPreferenceClickListener
直接附加到ListPreference对象。使用您在XML中指定的密钥来获取首选项的句柄。
由于填充entries
和entryValues
数组的代码必须同时在onCreate()
和onPreferenceClick
中运行,因此有必要将其提取为单独的方法-setListPreferenceData()
,以避免复制。
public class SettingsActivity extends PreferenceActivity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
try {
addPreferencesFromResource(R.xml.settings);
} catch (Exception e) {
}
final ListPreference listPreference = (ListPreference) findPreference("language");
// THIS IS REQUIRED IF YOU DON'T HAVE 'entries' and 'entryValues' in your XML
setListPreferenceData(listPreference);
listPreference.setOnPreferenceClickListener(new OnPreferenceClickListener() {
@Override
public boolean onPreferenceClick(Preference preference) {
setListPreferenceData(listPreference);
return false;
}
});
}
protected static void setListPreferenceData(ListPreference lp) {
CharSequence[] entries = { "English", "French" };
CharSequence[] entryValues = {"1" , "2"};
lp.setEntries(entries);
lp.setDefaultValue("1");
lp.setEntryValues(entryValues);
}
}
使用[PreferenceFragment&JAVA设置键,而不是https://stackoverflow.com/a/13828912/1815624中显示的PreferenceFragmentity&XML,此答案基于:
如果想要的是在初始化初始ListPreference对象之后能够动态更改列表中的项目,则需要将OnPreferenceClickListener
直接附加到ListPreference对象。使用具有在JAVA源文件中指定的(作为CUSTOM_LIST
)的键来获取首选项的句柄。
由于填充entries
和entryValues
数组的代码必须同时在onCreate()
和onPreferenceClick
中运行,因此有必要将其提取到单独的方法中-setListPreferenceData()
以免重复。
/**
* This fragment shows data and sync preferences only. It is used when the
* activity is showing a two-pane settings UI.
*/
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public static class myCustomPreferenceFragment extends PreferenceFragment {
final private String CUSTOM_LIST= "custom_list";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.pref_custom_frag);
PreferenceCategory targetCategory = (PreferenceCategory) findPreference("CUSTOM_FRAG");
final ListPreference lp = setListPreferenceData((ListPreference) findPreference(CUSTOM_LIST), getActivity());
lp.setOnPreferenceClickListener(new Preference.OnPreferenceClickListener() {
@Override
public boolean onPreferenceClick(Preference preference) {
setListPreferenceData(lp, getActivity());
return false;
}
});
setHasOptionsMenu(true);
targetCategory.addPreference(lp);
bindPreferenceSummaryToValue(targetCategory);
bindPreferenceSummaryToValue(lp);
}
protected ListPreference setListPreferenceData(ListPreference lp, Activity mActivity) {
CharSequence[] entries = { "One", "Two", "Three" };
CharSequence[] entryValues = { "1", "2", "3" };
if(lp == null)
lp = new ListPreference(mActivity);
lp.setEntries(entries);
lp.setDefaultValue("1");
lp.setEntryValues(entryValues);
lp.setTitle("Number Of blahs");
lp.setSummary(lp.getEntry());
lp.setDialogTitle("Number of Blah objects");
lp.setKey(CUSTOM_LIST);
return lp;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == android.R.id.home) {
startActivity(new Intent(getActivity(), SettingsActivity.class));
return true;
}
return super.onOptionsItemSelected(item);
}
}
XML布局:
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
<PreferenceCategory
android:key="CUSTOM_FRAG"
android:title="Some Options">
</PreferenceCategory>
</PreferenceScreen>
我解决了扩展ListPreference的问题。这很简单。
public class DListPref extends ListPreference
{
public interface LoadingListener
{
void setData(ListPreference lp);
}
LoadingListener TheLL;
public void setLoadingListener(LoadingListener l)
{
TheLL = l;
}
@Override
protected void onPrepareDialogBuilder(AlertDialog.Builder builder)
{
if(TheLL!=null)
{
TheLL.setData(this);
}
super.onPrepareDialogBuilder(builder);
}
//Do not mind the rest of this class, as they are auto-generated boilerplate code.
public DListPref(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes)
{
super(context, attrs, defStyleAttr, defStyleRes);
}
public DListPref(Context context, AttributeSet attrs, int defStyleAttr)
{
super(context, attrs, defStyleAttr);
}
public DListPref(Context context, AttributeSet attrs)
{
super(context, attrs);
}
public DListPref(Context context)
{
super(context);
}
}
然后我只是将名称更改为XML中的类。
<my.company.DListPref
android:defaultValue="-1"
android:key="damn"
android:title="vegetables"/>
然后我只是在onCreate上进行了此操作。
DListPref lp = (DListPref) findPreference("damn");
lp.setLoadingListener(new DListPref.LoadingListener()
{
@Override
public void setData(ListPreference lp)
{
lp.setEntries(new String[]{"doge", "wow"});
lp.setEntryValues(new String[] {"1", "2"});
lp.setDefaultValue("1");
}
});
立即工作。实际上,我从未想到过会如此轻松。