将PreferenceFragment添加到FragmentPagerAdapter

Question

我正试图将一个PreferenceFragment添加到FragmentPagerAdapter中。

我的类继承自FragmentActivity，我已经尝试过使用下面显示的FragmentTransaction，以及尝试添加到容器中，但似乎无法使任何事情起作用。没有抛出错误，实际上什么都没有发生。

主活动：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
    mViewPager = (ViewPager) findViewById(R.id.pager);
    mViewPager.setAdapter(mSectionsPagerAdapter);
}

activity_main.xml:

<android.support.v4.view.ViewPager 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/pager"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >
</android.support.v4.view.ViewPager>

我的选项菜单选择：

android.app.FragmentManager fm;
@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    case R.id.menu_settings:
        JJSettings settings = new JJSettings();
        fm = getFragmentManager();
        FragmentTransaction fragTrans = fm.beginTransaction();
        // I also tried `replace()` here as well. Same 'nothing happens' result.
        fragTrans.add(settings, "settings");
        fragTrans.commit();
        return true;
    case R.id.menu_help:
        menuHelp();
        return true;
    default:
        return super.onOptionsItemSelected(item);
    }
}

我的设置 片段：

public class JJSettings extends PreferenceFragment {

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

如果可能的话，我更倾向于使用Fragments，这意味着我宁愿不扩展PreferenceActivity或将用户带到调用PreferenceFragment的另一个Activity，如果有可能的话。我只是希望我在研究中错过了什么。

public class SectionsPagerAdapter extends FragmentPagerAdapter {
    private int _count = 2;

    public SectionsPagerAdapter(FragmentManager fm) { super(fm); }

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        return super.instantiateItem(container, position);
    }

    @Override
    public Fragment getItem(int position) {
        switch (position) {
        case 0:
            return new JJMainFragment();
        case 1:
            return new JJPendingFragment();
        default:
            return null;
        }
    }

    public void setCount(int count) { this._count = count; }

    @Override
    public int getCount() { return this._count; }

    @Override
    public CharSequence getPageTitle(int position) {
        switch (position) {
        case 0:
            return getString(R.string.c_list).toUpperCase(Locale.ENGLISH);
        case 1:
            return getString(R.string.c_pending).toUpperCase(Locale.ENGLISH);
        }
        return null;
    }
}

- jnthnjns

---

你能发一下你的SectionsPagerAdapter代码吗？ - Karakuri

@Karakuri 已添加，不太确定您为什么想看它，我不想将设置/首选项添加到 ViewPager 中。 - jnthnjns

Answer 1

这个答案引导我使用包含真正的android.app.Fragments的FragmentPagerAdapter来支持PreferenceFragment的v13支持库，从而找到了解决方案。

假设您使用Eclipse并使用“Scrollable Tabs + Swipe”导航运行新应用程序向导（它提供了v4分页器样板），下面是您需要进行的升级修改:

• 从libs文件夹中删除“android-support-v4.jar”文件
• 从SDK_PATH \ extras \ android \ support \ v13复制“android-support-v13.jar”; 如果不存在，请使用SDK管理器安装或更新“Extras / Android Support Library”

然后，在Java文件中:

• 将FragmentPagerAdapter导入从v4更改为v13
• 将FragmentActivity更改为普通Activity
• 更改对getSupportFragmentManager的调用为getFragmentManager
• 从android.app导入所有必要的类，而不是android.support.v4
• （除了：您仍然需要使用v4 ViewPager，但它是兼容的）

我在下面复制了修改后的源代码，并验证了最新的Jellybean。

MainActivity.java:

package com.example.pagerwithpreferencesfragment;

import java.util.Locale;

import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.os.Bundle;
import android.preference.PreferenceFragment;
import android.support.v13.app.FragmentPagerAdapter; // instead of v4.app...
import android.support.v4.view.ViewPager;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

public class MainActivity extends Activity { // no longer FragmentActivity

    // these comments are now out-of-date; v13, not v4
    /**
     * The {@link android.support.v4.view.PagerAdapter} that will provide
     * fragments for each of the sections. We use a
     * {@link android.support.v4.app.FragmentPagerAdapter} derivative, which
     * will keep every loaded fragment in memory. If this becomes too memory
     * intensive, it may be best to switch to a
     * {@link android.support.v4.app.FragmentStatePagerAdapter}.
     */
    SectionsPagerAdapter mSectionsPagerAdapter;

    /**
     * The {@link ViewPager} that will host the section contents.
     */
    ViewPager mViewPager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Create the adapter that will return a fragment for each of the three
        // primary sections of the app.
        mSectionsPagerAdapter = new SectionsPagerAdapter(
                getFragmentManager()); // instead of getSupportFragmentMangager

        // Set up the ViewPager with the sections adapter.
        mViewPager = (ViewPager) findViewById(R.id.pager);
        mViewPager.setAdapter(mSectionsPagerAdapter);

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    /**
     * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
     * one of the sections/tabs/pages.
     */
    public class SectionsPagerAdapter extends FragmentPagerAdapter {

        public SectionsPagerAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {
            // this is just to show it compiles
            if (position == 0) {
                // you should really make this a public class elsewhere..
                return new PreferenceFragment() {
                    @Override
                    public void onCreate(Bundle savedInstanceState) {
                        super.onCreate(savedInstanceState);
                        addPreferencesFromResource(R.xml.settings_preferences);
                    }
                };
            }
            // getItem is called to instantiate the fragment for the given page.
            // Return a DummySectionFragment (defined as a static inner class
            // below) with the page number as its lone argument.
            Fragment fragment = new DummySectionFragment();
            Bundle args = new Bundle();
            args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, position + 1);
            fragment.setArguments(args);
            return fragment;
        }

        @Override
        public int getCount() {
            // Show 3 total pages.
            return 3;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            Locale l = Locale.getDefault();
            switch (position) {
            case 0:
                return getString(R.string.title_section1).toUpperCase(l);
            case 1:
                return getString(R.string.title_section2).toUpperCase(l);
            case 2:
                return getString(R.string.title_section3).toUpperCase(l);
            }
            return null;
        }
    }

    /**
     * A dummy fragment representing a section of the app, but that simply
     * displays dummy text.
     */
    public static class DummySectionFragment extends Fragment {
        /**
         * The fragment argument representing the section number for this
         * fragment.
         */
        public static final String ARG_SECTION_NUMBER = "section_number";

        public DummySectionFragment() {
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_main_dummy,
                    container, false);
            TextView dummyTextView = (TextView) rootView
                    .findViewById(R.id.section_label);
            dummyTextView.setText(Integer.toString(getArguments().getInt(
                    ARG_SECTION_NUMBER)));
            return rootView;
        }
    }

}

设置_偏好设置.xml：

<?xml version="1.0" encoding="utf-8"?>

<PreferenceScreen
   xmlns:android="http://schemas.android.com/apk/res/android">

   <PreferenceCategory
      android:key="my_category_key"
      android:title="My Title">

       <CheckBoxPreference
         android:key="pref_key"
         android:title="Title"
         android:summary="Summary"
         android:defaultValue="false"
         />

   </PreferenceCategory>

</PreferenceScreen>

- PseudoNoise

---

谢谢。我看到了一个类似的问题在这里，它解决了你的问题根源；v4分页器不支持android.app.Fragment，而是它的v4版本，而PreferenceFragment没有从中派生出来。 - PseudoNoise

这个很好用。你详细的描述帮我省了很多麻烦。谢谢！ - ndsc

@DivyaRamakrishnan 正确，您必须坚持使用v4支持库来支持较低版本的设备，并且不使用android.app.fragment。 - PseudoNoise

如果您使用Android Studio，则为com.android.support:support-v13:23.1.1。 - zackygaurav

非常感谢，这刚好解决了我在v4库中遇到的几个问题。关于如何让世界变得更加简单的说明非常棒！ - PKlumpp

Answer 2

文档

我认为你需要为片段事务指定一个容器视图ID。尝试将其设置为您的ViewPager的ID。或者，将ViewPager放置在另一个容器中，给它一个ID，并使用它。

- Karakuri