java - 将向上按钮添加到 PreferenceScreen

Question

我不知道如何在 PreferenceScreen 中实现向上按钮。向上按钮在您的应用程序图标旁边的操作栏中显示一个插入符号，允许您导航应用程序的层次结构，更多信息 here .

我有一个首选项 fragment ，当我的主要 Activity 打开时显示，我可以通过添加此行“getActionBar().setDisplayHomeAsUpEnabled(true);”来显示向上按钮:

 protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    getActionBar().setDisplayHomeAsUpEnabled(true);
    getFragmentManager().beginTransaction()
    .replace(android.R.id.content, new SettingsFragment())
    .commit();

这会导致向上按钮显示在首选项 fragment 中，但我只想在我的其中一个 PreferenceScreens 打开时显示向上按钮，从而允许导航到主 PreferenceFragment.

我的应用类似于主设置应用。只有从主“设置”应用程序打开的子屏幕(例如“位置访问”)具有向上箭头。

Answer 1

从这里question ，我只是将这两个代码块添加到我的偏好 fragment 中:

@Override
public boolean onPreferenceTreeClick(PreferenceScreen preferenceScreen, Preference    preference) {
super.onPreferenceTreeClick(preferenceScreen, preference);

// If the user has clicked on a preference screen, set up the action bar
if (preference instanceof PreferenceScreen) {
    initializeActionBar((PreferenceScreen) preference);
}

return false;
}

还有这个:

 /** Sets up the action bar for an {@link PreferenceScreen} */
    public static void initializeActionBar(PreferenceScreen preferenceScreen) {
    final Dialog dialog = preferenceScreen.getDialog();

    if (dialog != null) {
        // Inialize the action bar
        dialog.getActionBar().setDisplayHomeAsUpEnabled(true);

        // Apply custom home button area click listener to close the PreferenceScreen because PreferenceScreens are dialogs which swallow
        // events instead of passing to the activity
        // Related Issue: https://code.google.com/p/android/issues/detail?id=4611
        View homeBtn = dialog.findViewById(android.R.id.home);

        if (homeBtn != null) {
            OnClickListener dismissDialogClickListener = new OnClickListener() {
                @Override
                public void onClick(View v) {
                    dialog.dismiss();
                }
            };

            // Prepare yourselves for some hacky programming
            ViewParent homeBtnContainer = homeBtn.getParent();

            // The home button is an ImageView inside a FrameLayout
            if (homeBtnContainer instanceof FrameLayout) {
                ViewGroup containerParent = (ViewGroup) homeBtnContainer.getParent();

                if (containerParent instanceof LinearLayout) {
                    // This view also contains the title text, set the whole view as clickable
                    ((LinearLayout) containerParent).setOnClickListener(dismissDialogClickListener);
                } else {
                    // Just set it on the home button
                    ((FrameLayout) homeBtnContainer).setOnClickListener(dismissDialogClickListener);
                }
            } else {
                // The 'If all else fails' default case
                homeBtn.setOnClickListener(dismissDialogClickListener);
            }
        }    
    }
}