java 如何在 Android 中为 SwitchPreference 设置默认值？
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How to set default value for SwitchPreference in Android?
提问by Lidia
Does anyone used SwitchPreferenceclass from Android and knows how to set the default value? I have implemented it programmatically:
有没有人使用SwitchPreference过 Android 的类并且知道如何设置默认值？我已经以编程方式实现了它：
SwitchPreference switch = new SwitchPreference(this);
switch.setKey("preference_my_key");
switch.setTitle(R.string.preference_title_my_title);
switch.setSummary(R.string.preference_summary_my_summary);
Boolean isChecked = Manager.myMethodIsChecked(MyActivity.this);
switch.setChecked( isChecked );
switch.setOnPreferenceChangeListener(new OnPreferenceChangeListener() {
@Override
public boolean onPreferenceChange(Preference preference, Object newValue) {
try {
boolean selected = Boolean.parseBoolean(newValue.toString());
if ( !selected ) {
//do something
}
} catch (Throwable e) {
e.printStackTrace();
}
return true;
}
});
category.addPreference(switch);
Preferences saves all values into its XML file: app_package_name_preferences.xml. First time when app is loaded, switch has default "false" values. But I need sometimes to make default value "true". I tried few methods,but nothing works.
首选项将所有值保存到其 XML 文件中：app_package_name_preferences.xml. 第一次加载应用程序时，开关具有默认的“ false”值。但有时我需要将默认值设为“ true”。我尝试了几种方法，但没有任何效果。
switch.setChecked( true );
switch.setDefaultValue(true);
采纳答案by Lidia
As I told, I write preferences programmatically:
正如我所说，我以编程方式编写首选项：
PreferenceScreen root = getPreferenceManager().createPreferenceScreen(this);
PreferenceCategory catView = new PreferenceCategory(this);
catView.setTitle(R.string.preference_category_view);
root.addPreference(catView);
final SwitchPreference switchSplash= new SwitchPreference(this);
switchSplash.setKey(PreferenceKeys.SPLASH);
//-----the above code----
switchSplash.setChecked(false); // LINE 1
catView.addPreference(switchSplash); // LINE 2
While debugging I found that truevalue is set in LINE 1, but when I add switchSplashinto catView, the values of switchSplashis reset to false, because catViewsets values from preferences.xml.
That's why I changed all needed values into the XML
在调试时，我发现true在LINE 1 中设置了值，但是当我添加switchSplash到 时catView， 的值switchSplash被重置为false，因为catView设置了来自首选项.xml 的值。
这就是我将所有需要的值更改为 XML 的原因
SharedPreferences.Editor editor = root.getPreferenceManager().getSharedPreferences().edit();
editor.putBoolean(PreferenceKeys.SPLASH, true);
editor.commit();
回答by kamasuPaul
Incase anyone is still looking for the answer here,you can use this attribute
app:defaultvalue="true"on your <Switchpreferencecompat/>in the xml
柜面任何人仍在寻找答案在这里，你可以使用这个属性
app:defaultvalue="true"在你<Switchpreferencecompat/>的XML
回答by erbsman
If you trying to get the boolean out of newValue
如果您试图从 newValue 中获取布尔值
boolean selected = Boolean.parseBoolean(newValue.toString());
your going about this in a strange and I guess incorrect way. If newValue is a Boolean, (check with instanceof) then just cast newValue to be a Boolean.
你以一种奇怪的方式处理这件事，我猜是不正确的方式。如果 newValue 是一个布尔值，（用 instanceof 检查）然后将 newValue 转换为一个布尔值。
boolean selected = (Boolean) newValue;
Is that what your trying to achieve?
这就是你想要达到的目标吗？
