一个简单的问题，如何使用操作栏的getDisplayOptions()?

Simple question how do I use getDisplayOptions() of action bar?

无论何时更改ActionBar中的显示选项，都会在内部调用ActionBar.setDisplayOptions(int options, int mask)，以将该显示选项与相应的位掩码配对.

Whenever you change the display options in the ActionBar, ActionBar.setDisplayOptions(int options, int mask) is called internally to pair that display option with the corresponding bitmask.

例如，当调用ActionBar.setDisplayHomeAsUpEnabled时，内部调用ActionBar.setDisplayOptions(int options, int mask)是这样的:

For instance, when ActionBar.setDisplayHomeAsUpEnabled is called, internally ActionBar.setDisplayOptions(int options, int mask) is called like this:

setDisplayOptions(showHomeAsUp ? DISPLAY_HOME_AS_UP : 0, DISPLAY_HOME_AS_UP);

因此，如果要检查是否启用了特定的显示选项，只需使用按位操作将该掩码与0进行比较即可.

So, if you want to check to see if particular display option is enabled, you just compare that mask to 0 using a bitwise operation.

// Retrieve the current set of display options
final int displayOptions = actionBar.getDisplayOptions();
// Determine which display options are enabled
final boolean isShowHomeEnabled = (displayOptions & ActionBar.DISPLAY_SHOW_HOME) != 0;
final boolean isHomeAsUpEnabled = (displayOptions & ActionBar.DISPLAY_HOME_AS_UP) != 0;
final boolean isShowTitleEnabled = (displayOptions & ActionBar.DISPLAY_SHOW_TITLE) != 0;
final boolean isUseLogoEnabled = (displayOptions & ActionBar.DISPLAY_USE_LOGO) != 0;
final boolean isShowCustomEnabled = (displayOptions & ActionBar.DISPLAY_SHOW_CUSTOM) != 0;

完整的示例可能类似于:

A complete example might be something like:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    final ActionBar actionBar = getActionBar();
    actionBar.setDisplayHomeAsUpEnabled(true);
    actionBar.setDisplayShowTitleEnabled(false);
    actionBar.setDisplayUseLogoEnabled(true);

    // Retrieve the current set of display options
    final int displayOptions = actionBar.getDisplayOptions();
    // Determine which display options are enabled
    final boolean isShowHomeEnabled = (displayOptions & ActionBar.DISPLAY_SHOW_HOME) != 0;
    final boolean isHomeAsUpEnabled = (displayOptions & ActionBar.DISPLAY_HOME_AS_UP) != 0;
    final boolean isShowTitleEnabled = (displayOptions & ActionBar.DISPLAY_SHOW_TITLE) != 0;
    final boolean isUseLogoEnabled = (displayOptions & ActionBar.DISPLAY_USE_LOGO) != 0;
    final boolean isShowCustomEnabled = (displayOptions & ActionBar.DISPLAY_SHOW_CUSTOM) != 0;

    System.out.println("show home: " + isShowHomeEnabled);
    System.out.println("home as up: " + isHomeAsUpEnabled);
    System.out.println("show title: " + isShowTitleEnabled);
    System.out.println("use logo: " + isUseLogoEnabled);
    System.out.println("show custom: " + isShowCustomEnabled);
}

哪个会打印:

show home: false
home as up: true
show title: false
use logo: true
show custom: false