安卓：更新列表preference与在preferenceChangeListener [英] Android: update ListPreference with OnPreferenceChangeListener

问题描述

下面是我的preferences.xml

Here's my preferences.xml

<?xml version="1.0" encoding="utf-8"?>

<ListPreference
    android:key="KEY_1"
    android:title="Title"
    android:summary="Summary"
    android:dialogTitle="Dialog"
    />
<ListPreference
    android:key="KEY_2"
     />   
<ListPreference
    android:key="KEY_3"
     />   
<ListPreference
    android:key="KEY_4"
     />

这里是Settings.java：

And here is the Settings.java:

public class Settings extends PreferenceActivity {
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    addPreferencesFromResource(R.xml.preferences);

// some methods to generate entries and values for ListPreference
final List List_1 = // something
final List List_2 = // something
final List List_3 = // something

String[] entry_1 = List_1.toArray(new String[List_1.size()]);
String[] entry_2 = List_2.toArray(new String[List_2.size()]);
String[] entry_3 = List_3.toArray(new String[List_3.size()]);

String[] value_1 = List_1.toArray(new String[List_1.size()]);
String[] value_2 = List_2.toArray(new String[List_2.size()]);
String[] value_3 = List_3.toArray(new String[List_3.size()]);


    // set arrays for entries and values    
 final ListPreference lp1 = (ListPreference)findPreference("KEY_1");
 lp1.setEntries(entry_1);
 lp1.setEntryValues(value_2); 

ListPreference lp2 = (ListPreference)findPreference("KEY_2");
lp2.setEntries(entry_2);
lp2.setEntryValues(value_1);

ListPreference lp3 = (ListPreference)findPreference("KEY_3");
lp3.setEntries(entry_2);
lp3.setEntryValues(value_2);

ListPreference lp4 = (ListPreference)findPreference("KEY_4");
lp4.setEntries(entry_2);
lp4.setEntryValues(value_3);

// update lp2, lp3, lp4

        lp1.setOnPreferenceChangeListener(new OnPreferenceChangeListener() {
            @Override
            public boolean onPreferenceChange(Preference preference, Object newValue) {
                String listValue = (String) newValue;

                ListPreference lp2 = (ListPreference)findPreference("KEY_2");
                lp2.setDefaultValue(listValue);

                ListPreference lp3 = (ListPreference)findPreference("KEY_3");
                lp3.setDefaultValue(listValue);

                ListPreference lp4 = (ListPreference)findPreference("KEY_4");
                lp4.setDefaultValue(listValue);

                return true;
            }
        });
    }
}

这很适合我的只有一次。缺少什么我在这里作出LP2，LP3和LP4以后的更新？我猜setDefaultValue创建只是一个时间输入到共享preferences是什么？

This works well for me for only one time. What am I missing here to make the updates on lp2, lp3 and lp4 later on? I guess setDefaultValue creates just that one-time-input to shared preferences?

推荐答案

我怀疑你的匿名监听器是垃圾回收 - 添加一些调试输出，看是否监听器被称为

I suspect your anonymous listener is garbage collected - add some debug prints to see if the listener is called

lp1.setOnPreferenceChangeListener(new OnPreferenceChangeListener() {
    @Override
    public boolean onPreferenceChange(Preference preference, Object newValue) {
        Log.d("Listener", "I listen");
        String listValue = (String) newValue;
        // rest is the same
    }
});

如果您没有看到调试打印您的侦听器移动到一个类字段和：

If you see no debug print move your listener to a class field and :

public class Settings extends PreferenceActivity {

    private OnPreferenceChangeListener mListener=new OnPreferenceChangeListener(){
        @Override
        public boolean onPreferenceChange(Preference preference, Object newValue){
            // as before
        }
    };
    // etc - I guess the line below is in onCreate() - correct your formatting !
    lp1.setOnPreferenceChangeListener(mListener);
    }
}

这篇关于安卓：更新列表preference与在preferenceChangeListener的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！