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我正在尝试使用带有 ViewPager 的ABS SherlockFragmentActivity 进行选项卡式活动，并希望其中一个选项卡包含首选项活动/片段。

由于 ABS 没有 SherlockPreferenceFragment 或任何对 PreferenceFragment 的支持，我找到了使用UnifiedPreference的可能解决方案

UnifiedPreference 可以自己工作，演示效果很好，但是如果我尝试在我的 ActionBarSherlock 支持的选项卡中实现它，它会崩溃并显示以下消息：

04-18 03:59:26.000: E/AndroidRuntime(8437): FATAL EXCEPTION: main
04-18 03:59:26.000: E/AndroidRuntime(8437): java.lang.ClassCastException: si.neanonimen.Settings$NetSettingsPrefsFragment cannot be cast to android.support.v4.app.Fragment
04-18 03:59:26.000: E/AndroidRuntime(8437):     at android.support.v4.app.Fragment.instantiate(Fragment.java:384)

看起来UnifiedPreferenceFragment没有延伸android.support.v4.app.Fragment。有没有办法解决？有没有人设法得到一个有效的例子？

我目前的代码是：

设置：

public class Settings extends UnifiedSherlockPreferenceActivity {

    public static String tag = "Settings";

    @Override
    public void onCreate(Bundle savedInstanceState) {
        setHeaderRes(R.xml.pref_headers);
        super.onCreate(savedInstanceState); 
    }

    public static class NetSettingsPrefsFragment extends UnifiedPreferenceFragment {}
}

选项卡式活动：

public class FragmentTabs extends SherlockFragmentActivity {
    private TabHost     mTabHost;
    private ViewPager   mViewPager;
    private TabsAdapter mTabsAdapter;

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

        setContentView(R.layout.fragment_tabs);
        mTabHost = (TabHost) findViewById(android.R.id.tabhost);
        mTabHost.setup();

        mViewPager = (ViewPager) findViewById(R.id.pager);

        mTabsAdapter = new TabsAdapter(this, mTabHost, mViewPager);

        // obviously THIS is the problem
        mTabsAdapter.addTab(mTabHost.newTabSpec("settings").setIndicator("Nastavitve"), Settings.NetSettingsPrefsFragment.class, null);

        if (savedInstanceState != null) {
            mTabHost.setCurrentTabByTag(savedInstanceState.getString("tab"));
        }
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putString("tab", mTabHost.getCurrentTabTag());
    }

    public static class TabsAdapter extends FragmentPagerAdapter implements TabHost.OnTabChangeListener, ViewPager.OnPageChangeListener {
        private final Context               mContext;
        private final TabHost               mTabHost;
        private final ViewPager             mViewPager;
        private final ArrayList<TabInfo>    mTabs   = new ArrayList<TabInfo>();

        static final class TabInfo {
            //private final String  tag;
            private final Class<?>  clss;
            private final Bundle    args;

            TabInfo(String _tag, Class<?> _class, Bundle _args) {
                //tag = _tag;
                clss = _class;
                args = _args;
            }
        }

        static class DummyTabFactory implements TabHost.TabContentFactory {
            private final Context   mContext;

            public DummyTabFactory(Context context) {
                mContext = context;
            }

            @Override
            public View createTabContent(String tag) {
                View v = new View(mContext);
                v.setMinimumWidth(0);
                v.setMinimumHeight(0);
                return v;
            }
        }

        public TabsAdapter(FragmentActivity activity, TabHost tabHost, ViewPager pager) {
            super(activity.getSupportFragmentManager());
            mContext = activity;
            mTabHost = tabHost;
            mViewPager = pager;
            mTabHost.setOnTabChangedListener(this);
            mViewPager.setAdapter(this);
            mViewPager.setOnPageChangeListener(this);
        }

        public void addTab(TabHost.TabSpec tabSpec, Class<?> clss, Bundle args) {
            tabSpec.setContent(new DummyTabFactory(mContext));
            String tag = tabSpec.getTag();

            TabInfo info = new TabInfo(tag, clss, args);
            mTabs.add(info);
            mTabHost.addTab(tabSpec);
            notifyDataSetChanged();
        }

        @Override
        public int getCount() {
            return mTabs.size();
        }

        @Override
        public Fragment getItem(int position) {
            TabInfo info = mTabs.get(position);
            return Fragment.instantiate(mContext, info.clss.getName(), info.args);
        }

        @Override
        public void onTabChanged(String tabId) {
            int position = mTabHost.getCurrentTab();
            mViewPager.setCurrentItem(position);
        }

        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {}

        @Override
        public void onPageSelected(int position) {
            // Unfortunately when TabHost changes the current tab, it kindly
            // also takes care of putting focus on it when not in touch mode.
            // The jerk.
            // This hack tries to prevent this from pulling focus out of our
            // ViewPager.
            TabWidget widget = mTabHost.getTabWidget();
            int oldFocusability = widget.getDescendantFocusability();
            widget.setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS);
            mTabHost.setCurrentTab(position);
            widget.setDescendantFocusability(oldFocusability);
        }

        @Override
        public void onPageScrollStateChanged(int state) {}
    }
}
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1 回答 1

1

我还需要在 Honeycomb（API 级别 11）之前的 Android 版本中实现 PreferenceFragment。正如您已经拥有的那样，我找到了 UnifiedPreference 库，但查看源代码我发现 UnifiedPreferenceFragment 从官方 Android API 扩展了 PreferenceFragment，因此不适用于 < API 级别 11。

这是我在那里发现的另一门课，但我还没有测试过：

希望能帮助到你！

你找到另一个解决方案了吗？希望 Android 用户能尽快将这个类添加到支持库中！

干杯，

于 2013-06-03T11:47:44.580 回答