以编程方式设置微调器文本颜色滞后、速度慢、瞬间颜色错误

TLDR:我的微调器瞬间显示错误的颜色。

我的旋转器有问题。每当我运行应用程序时，如果活动未缓存在内存中，它有时会滞后。在我可以将文本设置为正确的颜色之前，文本是默认颜色（如黑色）。看起来确实很不专业。

Video:请观看此屏幕录制以了解其实际效果：https://drive.google.com/file/d/0By2AG5yaBEhMRnRsbVBDU251STQ/view https://drive.google.com/file/d/0By2AG5yaBEhMRnRsbVBDU251STQ/view

How it looks for one split-second while loading the page:

How it looks after the lag time (and how it is supposed to look from the start):

Code:

public class MyActivity extends AppCompatActivity
{

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        Spinner spinner = (Spinner) findViewById(R.id.spinner);

        //Get rid of the normal toolbar's title, because the spinner is replacing the title.
        getSupportActionBar().setDisplayShowTitleEnabled(false);

        //Set the choices on the spinner by setting the adapter.
        spinner.setAdapter(new SpinnerAdapter(toolbar.getContext(), new String[]{"Overview", "Story", "Specifications", "Poll", "Video"}, accentColor, backgroundColor));

        //Set the listener for when each option is clicked.
        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener()
        {

            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id)
            {
                //Change the selected item's text color
                ((TextView) view).setTextColor(backgroundColor);
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent)
            {
            }
        });
    }
}

XML:

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android"
                                   xmlns:app="http://schemas.android.com/apk/res-auto"
                                   android:layout_width="match_parent"
                                   android:layout_height="wrap_content"
                                   android:background="@color/ColorPrimary"
                                   android:elevation="4dp">
    <Spinner
        android:id="@+id/spinner"
        app:popupTheme="@style/AppTheme.PopupOverlay"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
</android.support.v7.widget.Toolbar>

我做错了什么：

之前，我听从了建议这个答案 https://stackoverflow.com/a/15380215/2423194，并在中设置文本颜色onItemSelected方法，但该方法仅在 UI 完成后自动调用，并且您无法调用onItemSelected直接来自您的代码。这导致了滞后。 （但是当您从下拉列表中选择一个项目时仍然需要它 - 请参阅我对此问题的解决方案。）

解决方案：

策略是在 onCreate 完成之前获取“Selected”视图并设置其文本颜色。当我在调试器中测试它时，在调试过程中没有显示任何 UIonCreate方法，所以这保证有效。

我只需在调用后添加此代码setAdapter(...):

//Set the text color of the Spinner's selected view (not a drop down list view)
spinner.setSelection(0, true);
View v = spinner.getSelectedView();
((TextView)v).setTextColor(backgroundColor);

关键是调用spinner.setSelection(0, true) 与true范围。否则，如果你只是打电话spinner.setSelection(0)， 风景v将为空。我发现了这一点，感谢这个答案 https://stackoverflow.com/a/6800839/2423194.

完整方法：

这是完整的方法。NOTE:代码在onItemSelected仍然需要在那里！否则，每次从下拉列表中选择一个项目时，它的颜色都会错误。

@Override 
protected void onCreate(Bundle savedInstanceState)
{ 
    Spinner spinner = (Spinner) findViewById(R.id.spinner);

    //Get rid of the normal toolbar's title, because the spinner is replacing the title. 
    getSupportActionBar().setDisplayShowTitleEnabled(false); 

    //Set the choices on the spinner by setting the adapter. 
    spinner.setAdapter(new SpinnerAdapter(toolbar.getContext(), new String[]{"Overview", "Story", "Specifications", "Poll", "Video"}, accentColor, backgroundColor));

    //Set the text color of the Spinner's selected view (not a drop down list view)
    spinner.setSelection(0, true);
    View v = spinner.getSelectedView();
    ((TextView)v).setTextColor(backgroundColor);

    //Set the listener for when each option is clicked. 
    spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener()
    { 

        @Override 
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id)
        { 
           //Change the selected item's text color 
           ((TextView) view).setTextColor(backgroundColor);
        } 

        @Override 
        public void onNothingSelected(AdapterView<?> parent)
        { 
        } 
    }); 

} 

有关 setSelection 方法源代码的更多信息，请参阅此处的 AbsSpinner.java 代码：https://android.googlesource.com/platform/frameworks/base/+/jb-release/core/java/android/widget/AbsSpinner.java https://android.googlesource.com/platform/frameworks/base/+/jb-release/core/java/android/widget/AbsSpinner.java

这是 Spinner.java 以防有帮助：https://android.googlesource.com/platform/frameworks/base/+/jb-release/core/java/android/widget/Spinner.java https://android.googlesource.com/platform/frameworks/base/+/jb-release/core/java/android/widget/Spinner.java