发现坑
最近在配置项目主题的时候报了如下错误:
This Activity already has an action bar supplied by the window decor. Do not request Window.FEATURE_SUPPORT_ACTION_BAR
原因一
错误写法:
<style name="AppTheme.NoActionBar"
<item name="android:windowActionBar" false</item
<item name="android:windowNoTitle" true</item
<item name="android:windowDrawsSystemBarBackgrounds" true</item
<item name="android:statusBarColor" @android:color/transparent</item
</style
其中AppTheme使用的主题是AppCompat的主题,由于AppCompat主题下的windowActionBar和windowNoTitle的命名方式前都没有android字样,所以报错。
正确写法:
<style name="AppTheme.NoActionBar"
<item name="windowActionBar" false</item
<item name="windowNoTitle" true</item
<item name="android:windowDrawsSystemBarBackgrounds" true</item
<item name="android:statusBarColor" @android:color/transparent</item
</style
原因二
如果主题设置成有Actionbar的Theme并且没有配:
<item name="windowActionBar" false</item
<item name="windowNoTitle" true</item
也会出这样的错误。
看下源码:
在我们设置toolbar时候: ((AppCompatActivity)getActivity()).setSupportActionBar(toolbar);
点进源码可以看到源码调用逻辑是:
public void setSupportActionBar(@Nullable Toolbar toolbar) {
getDelegate().setSupportActionBar(toolbar);
}
在往下追一步,出真相了:
public void setSupportActionBar(Toolbar toolbar) {
if (!(mOriginalWindowCallback instanceof Activity)) {
// Only Activities support custom Action Bars
return;
}
//这里会去判有没有actionbar存在,如果有直接抛异常
final ActionBar ab = getSupportActionBar();
if (ab instanceof WindowDecorActionBar) {
throw new IllegalStateException("This Activity already has an action bar supplied " +
"by the window decor. Do not request Window.FEATURE_SUPPORT_ACTION_BAR and set " +
"windowActionBar to false in your theme to use a Toolbar instead.");
}
// If we reach here then we're setting a new action bar
// First clear out the MenuInflater to make sure that it is valid for the new Action Bar
mMenuInflater = null;
// If we have an action bar currently, destroy it
if (ab != null) {
ab.onDestroy();
}
if (toolbar != null) {
final ToolbarActionBar tbab = new ToolbarActionBar(toolbar,
((Activity) mContext).getTitle(), mAppCompatWindowCallback);
mActionBar = tbab;
mWindow.setCallback(tbab.getWrappedWindowCallback());
} else {
mActionBar = null;
// Re-set the original window callback since we may have already set a Toolbar wrapper
mWindow.setCallback(mAppCompatWindowCallback);
}
invalidateOptionsMenu();
}
主要在这里:
//这里会去判有没有actionbar存在,如果有直接抛异常
final ActionBar ab = getSupportActionBar();
if (ab instanceof WindowDecorActionBar) {
throw new IllegalStateException("This Activity already has an action bar supplied " +
"by the window decor. Do not request Window.FEATURE_SUPPORT_ACTION_BAR and set " +
"windowActionBar to false in your theme to use a Toolbar instead.");
}
好了,结束。
总结
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