問(wèn)題描述
這是我在開(kāi)發(fā)真實(shí)應(yīng)用程序時(shí)發(fā)現(xiàn)的錯(cuò)誤"，但我創(chuàng)建了一個(gè)空白項(xiàng)目來(lái)重現(xiàn)它.
This is a 'bug' that I discovered while working on a real app, but I created a blank project to reproduce it.
我有以下布局:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:id="@+id/root"
android:orientation="vertical"
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<com.example.test.testapp.MyEditText
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
MyEditText 類如下所示:
public class MyEditText extends EditText {
public MyEditText(Context context){
super(context);
}
public MyEditText(Context context, AttributeSet attrs){
super(context, attrs);
}
public MyEditText(Context context, AttributeSet attrs, int defStyle){
super(context, attrs, defStyle);
}
}
我的 styles.xml 文件是空的，除了主題
My styles.xml file is empty except for the Theme
<resources>
<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
<!-- Customize your theme here. -->
</style>
</resources>
我希望 MyEditText 看起來(lái)像普通的 EditText 并且它在 Android 5.0 上是這樣，但在 Android 2.3.7、Android 4.1.3 或 Android 4.4 上卻不是.4.
I would expect the MyEditText to look like the normal EditText and it does on Android 5.0, but not on Android 2.3.7, Android 4.1.3 or Android 4.4.4.
在那些 Android 版本上，EditText 的顏色不同，正常的在聚焦時(shí)有青色下劃線，自定義的有黑色下劃線:
On those Android versions the EditTexts differ in color, the normal one has a cyan underline when focused, the custom one has a black underline:
為什么會(huì)發(fā)生這種情況，我該如何預(yù)防?
Why is this happening and how can I prevent it?
編輯/更新:
Google 似乎已經(jīng)解決了這個(gè)問(wèn)題 在支持庫(kù)中引入 AppCompatEditText 類等.
Google seems to have adressed this in the support library by introducing, amongst others, an AppCompatEditText class.
推薦答案
為什么會(huì)這樣
因?yàn)槟褂玫氖?AppCompat.引用 關(guān)于該主題的博文:
Because you are using AppCompat. Quoting the blog post on the subject:
問(wèn):為什么我的 EditText(或上面列出的其他小部件)在我的棒棒糖之前的設(shè)備上沒(méi)有正確著色?
Q: Why is my EditText (or other widget listed above) not being tinted correctly on my pre-Lollipop device?
答:AppCompat 中的小部件著色通過(guò)攔截任何布局膨脹并在其位置插入一個(gè)特殊的著色感知版本的小部件來(lái)工作.對(duì)于大多數(shù)人來(lái)說(shuō)，這可以正常工作，但我可以想到一些不起作用的場(chǎng)景，包括:
A: The widget tinting in AppCompat works by intercepting any layout inflation and inserting a special tint-aware version of the widget in its place. For most people this will work fine, but I can think of a few scenarios where this won’t work, including:
- 您擁有自己的自定義小部件版本(即您已擴(kuò)展 EditText)
- 您正在創(chuàng)建沒(méi)有 LayoutInflater 的 EditText(即，調(diào)用 new EditText()).
因此，該行為是預(yù)期的.AppCompat 向后移植提供了一些輕量級(jí)的著色向后移植，但它不能處理所有情況.
So, the behavior is expected. The AppCompat backport provides some lightweight backporting of tinting, but it's not going to handle all cases.
如何預(yù)防?
即開(kāi)即用:
不要?jiǎng)?chuàng)建
EditText的子類，或者
在 AppCompat 上運(yùn)行時(shí)，查找色調(diào)并弄清楚如何自己應(yīng)用它，或許可以通過(guò)檢查 AppCompat 源代碼(假設(shè)它可用——我沒(méi)有尋找它)，或者
When running on AppCompat, look up the tint and figure out how to apply it yourself, perhaps by examining the AppCompat source code (assuming it's available -- I haven't looked for it), or
不要使用 AppCompat，并在 Android 5.0+ 設(shè)備上使用 Theme.Material 查看著色是否按預(yù)期工作
Do not use AppCompat, and see if tinting works as expected using Theme.Material on Android 5.0+ devices
未來(lái)的 AppCompat 可能會(huì)為子類提供某種系統(tǒng)來(lái)參與著色過(guò)程.除了這些之外，可能還有其他解決方案——這些都是我想到的.
It's possible that a future AppCompat could provide some sort of system for subclasses to participate in the tinting process. And there may be other solutions than these -- these are what come to mind.
這篇關(guān)于EditText 的子類看起來(lái)與 Android 4 上的普通 EditText 不同的文章就介紹到這了，希望我們推薦的答案對(duì)大家有所幫助，也希望大家多多支持html5模板網(wǎng)！