如何获得在 Android 中工作的首选项？
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How do I get preferences to work in Android?
提问by Dan T
I've really been struggling through this. New to Java/Android. I'm writing my first app and this is the first thing that has taken me longer than a couple days of searching to figure out. Here's the setup: It's a BAC calculator / drink counter:
我真的一直在努力解决这个问题。Java/Android 新手。我正在编写我的第一个应用程序，这是我花了几天时间才弄明白的第一件事。这是设置：这是一个 BAC 计算器/饮料计数器：
A formula is used to calculate the BAC. Here's the forumla:
使用公式计算 BAC。这里是论坛：
Bac = ((StandardDrinks / 2) * (GenderConstant / Weight)) - (0.017 * Hours);
So as you can see, being able to modify the gender and weight will produce more accurate and personalized results. So I have them as doubles:
如您所见，能够修改性别和体重将产生更准确和个性化的结果。所以我把它们作为双打：
double GenderConstant = 7.5; //9 for female
double Weight = 180;
To change these variables I would like the person to be able to go into the settings and choose different values. I have these things set up, but not linked to the variables shown above because I cannot for the life of me figure out how. Here they are:
要更改这些变量，我希望此人能够进入设置并选择不同的值。我已经设置了这些东西，但没有与上面显示的变量相关联，因为我一生都无法弄清楚如何。他们来了：
I press the menu button and this pops up. Great. I'll click Settings.
我按下菜单按钮，这会弹出。伟大的。我会点击设置。
Now the preferences pops up. Here is my preferences.xml:
现在弹出首选项。这是我的首选项.xml：
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
<PreferenceCategory android:title="Personal Settings">
<ListPreference
android:title="Gender"
android:summary="Verify or deny the presence of a Y chromosome."
android:key="genderPref"
android:defaultValue="male"
android:entries="@array/genderArray"
android:entryValues="@array/genderValues" />
<ListPreference
android:title="Weight"
android:summary="How much the planet pulls on you, in pounds."
android:key="weightPref"
android:defaultValue="180"
android:entries="@array/weightArray"
android:entryValues="@array/weightValues" />
</PreferenceCategory>
<PreferenceCategory android:title="Drink Settings">
<ListPreference
android:title="Beer Size"
android:summary="The volume of your beer, in ounces."
android:key="beerPref"
android:defaultValue="12"
android:entries="@array/beerArray"
android:entryValues="@array/beerValues" />
<ListPreference
android:title="Shot Size"
android:summary="The volume of your shot, in ounces."
android:key="shotPref"
android:defaultValue="1.5"
android:entries="@array/shotArray"
android:entryValues="@array/shotValues" />
<ListPreference
android:title="Wine Size"
android:summary="The volume of your wine, in ounces."
android:key="winePref"
android:defaultValue="5"
android:entries="@array/wineArray"
android:entryValues="@array/wineValues" />
</PreferenceCategory>
</PreferenceScreen>
Onward to the weight ListPreference:
继续权重 ListPreference：
And that shows up. The values are stored as string-arrays in res/values/arrays.xml. Here's a sample, of just the weight ones:
这出现了。这些值作为字符串数组存储在 res/values/arrays.xml 中。这是一个示例，仅包含重量示例：
<string-array name="weightArray">
<item>120 lbs</item>
<item>150 lbs</item>
<item>180 lbs</item>
<item>210 lbs</item>
<item>240 lbs</item>
<item>270 lbs</item>
</string-array>
<string-array name="weightValues">
<item>120</item>
<item>150</item>
<item>180</item>
<item>210</item>
<item>240</item>
<item>270</item>
</string-array>
This is basically as far as I've gotten. I can click a value, sure, but it doesn't change the formula because it's not linked with the doubles I created in DrinkingBuddy.java. All of the stuff displayed in the settings are just empty shells for now, including the spinner on the main layout (the default time is just set to 1 hour)
这基本上是我得到的。我可以单击一个值，当然，但它不会更改公式，因为它没有与我在 DrinkingBuddy.java 中创建的双打链接。设置中显示的所有内容现在都只是空壳，包括主布局上的微调器（默认时间设置为 1 小时）
I did create a Preferences.java and have tried implementing various combinations of code found in tutorials and resources around the web, but to no avail. Here it is anyway, filled with failed attempts to make beerPref (the settings option to change how many ounces in the beer) correlate with a variable in my main class:
我确实创建了一个 Preferences.java 并尝试实现在网上教程和资源中找到的各种代码组合，但无济于事。无论如何，这里充满了尝试使 beerPref（更改啤酒中多少盎司的设置选项）与我的主类中的变量相关的失败尝试：
package com.dantoth.drinkingbuddy;
import android.app.Activity;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.Preference;
import android.preference.PreferenceActivity;
import android.preference.Preference.OnPreferenceClickListener;
public class Preferences extends PreferenceActivity {
public static final String PREF_BEER_SIZE = "PREF_BEER_SIZE";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.preferences);
//Get the custom preference
Preference beerPref = (Preference) findPreference("beerPref");
beerPref.setOnPreferenceClickListener(new OnPreferenceClickListener() {
public boolean onPreferenceClick(Preference preference) {
SharedPreferences customSharedPreference = getSharedPreferences("myCustomSharedPrefs", Activity.MODE_PRIVATE);
SharedPreferences.Editor editor = customSharedPreference.edit();
editor.commit();
return true;
}}
);}
}
A full on tutorial and sample code would be AWESOME as I've yet to find any reliable guides out there.
完整的教程和示例代码会很棒，因为我还没有找到任何可靠的指南。
回答by ChrisV
I'm still working all this out myself, but (somewhat adapted from my version) I think your Preferences class only needs to do the following:
我仍在自己解决所有这些问题，但是（有点改编自我的版本）我认为您的 Preferences 类只需要执行以下操作：
public class Preferences extends PreferenceActivity {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// load the XML preferences file
addPreferencesFromResource(R.xml.preferences);
}
}
Then in your main class, you can refer to the preferences:
然后在你的主类中，你可以参考偏好：
public class DrinkingBuddy extends Activity
implements OnSharedPreferenceChangeListener {
private int weight;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
// register preference change listener
prefs.registerOnSharedPreferenceChangeListener(this);
// and set remembered preferences
weight = Integer.parseInt((prefs.getString("weightPref", "120")));
// etc
}
// handle updates to preferences
public void onSharedPreferenceChanged(SharedPreferences prefs, String key) {
if (key.equals("weightValues")) {
weight = Integer.parseInt((prefs.getString("weightPref", "120")));
}
// etc
}
}
The saving of preference updates is handled for you.
为您处理首选项更新的保存。
(Not too sure about public/private declarations!)
（不太确定公共/私人声明！）
回答by Pentium10
You are requesting probably two different set of preference files.
您可能正在请求两组不同的首选项文件。
Make sure you store the ListPreference values in the same files.
Start up adbroll to the cd /data/data/com.your.packageand look for folders and files of type preferences.
确保将 ListPreference 值存储在相同的文件中。启动adb滚动到cd /data/data/com.your.package并查找类型首选项的文件夹和文件。
I think the bug is that you specify a different file than the one the setting has been saved too:
我认为错误在于您指定的文件与保存设置的文件不同：
Try changing this:
尝试改变这个：
SharedPreferences preferences = getSharedPreferences(PREF_FILE_NAME, MODE_PRIVATE);
to
到
SharedPreferences preferences = PreferenceManager
.getDefaultSharedPreferences(context);
Then you will probably have to query only
那么你可能只需要查询
preferences.getString('weightPref', null);
Also you do not need the Editor. The preferences are saved automatically.
你也不需要 Editor。首选项会自动保存。
回答by oabarca
For most apps, it is most convinient to use the default shared preferences. You can get from anywhere in you app them with:
对于大多数应用程序，使用默认共享首选项最为方便。您可以通过以下方式从应用程序的任何位置获取它们：
SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(context);
You can save new variables into it with:
您可以使用以下命令将新变量保存到其中：
sp.edit().putString("var_name", "var value".apply();
