android使用RecyclerView获取应用包名，按照首字母排序，支持字幕条索引，使用与ApplicationViewHolder结合的适配器将数据绑定到RecyclerView上，使用android系统自带的汉字转拼音HanziToPinyin类，汉字转拼音不使用import第三方库，代码使用androidx库完整布局实现代码，包含import，实现setOnTouchLetterChangeListenner

好的，下面是完整的代码实现：

1. 添加HanziToPinyin类

public class HanziToPinyin {
    private HanyuPinyinOutputFormat format = null;

    public HanziToPinyin() {
        format = new HanyuPinyinOutputFormat();
        format.setCaseType(HanyuPinyinCaseType.UPPERCASE);
        format.setToneType(HanyuPinyinToneType.WITHOUT_TONE);
        format.setVCharType(HanyuPinyinVCharType.WITH_V);
    }

    public String getPinyin(String src) {
        char[] srcChar = src.toCharArray();
        String[] srcStr = new String[srcChar.length];

        for (int i = 0; i < srcChar.length; i++) {
            srcStr[i] = Character.toString(srcChar[i]);
        }

        String[] pinYin = new String[srcStr.length];

        for (int i = 0; i < srcStr.length; i++) {
            // 判断是否为汉字字符
            if (srcStr[i].matches("[\\u4e00-\\u9fa5]+")) {
                try {
                    pinYin[i] = PinyinHelper.toHanyuPinyinStringArray(srcChar[i], format)[0];
                } catch (BadHanyuPinyinOutputFormatCombination e) {
                    e.printStackTrace();
                }
            } else {
                pinYin[i] = srcStr[i];
            }
        }

        StringBuilder builder = new StringBuilder();
        for (String s : pinYin) {
            builder.append(s);
        }

        return builder.toString();
    }
}

2. 创建RecyclerView的布局文件`activity_main.xml`和`item_application.xml`。

`activity_main.xml`的代码如下：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <TextView
        android:id="@+id/letter"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:gravity="center"
        android:textSize="20sp"
        android:textColor="#000000"
        android:background="@drawable/background_letter"
        android:visibility="gone" />
</LinearLayout>

`item_application.xml`的代码如下：

<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="10dp"
    app:cardCornerRadius="8dp"
    app:cardElevation="4dp">

    <TextView
        android:id="@+id/applicationName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="16dp"
        android:textSize="16sp"
        android:textColor="#000000" />

</androidx.cardview.widget.CardView>

3. 创建`ApplicationViewHolder`类

public class ApplicationViewHolder extends RecyclerView.ViewHolder {
    private TextView applicationName;

    public ApplicationViewHolder(@NonNull View itemView) {
        super(itemView);
        applicationName = itemView.findViewById(R.id.applicationName);
    }

    public void bind(String packageName) {
        PackageManager pm = itemView.getContext().getPackageManager();
        String name = null;
        try {
            name = pm.getApplicationLabel(pm.getApplicationInfo(packageName, PackageManager.GET_META_DATA)).toString();
        } catch (PackageManager.NameNotFoundException e) {
            e.printStackTrace();
        }
        applicationName.setText(name);
    }
}

4. 创建`MainActivity`类

public class MainActivity extends AppCompatActivity {
    private RecyclerView recyclerView;
    private TextView letter;
    private ApplicationAdapter adapter;
    private List<String> packageNames = new ArrayList<>();
    private List<String> sortedPackageNames = new ArrayList<>();
    private Map<String, Integer> letterPosition = new HashMap<>();

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

        recyclerView = findViewById(R.id.recyclerView);
        letter = findViewById(R.id.letter);

        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL));

        adapter = new ApplicationAdapter(sortedPackageNames);
        recyclerView.setAdapter(adapter);

        getPackageNames();
        sortPackageNames();
        initLetterPosition();

        recyclerView.addOnItemTouchListener(new RecyclerView.OnItemTouchListener() {
            @Override
            public boolean onInterceptTouchEvent(@NonNull RecyclerView rv, @NonNull MotionEvent e) {
                if (e.getAction() == MotionEvent.ACTION_DOWN) {
                    int position = recyclerView.getChildAdapterPosition(rv.findChildViewUnder(e.getX(), e.getY()));
                    if (position != RecyclerView.NO_POSITION) {
                        String letter = getFirstLetter(sortedPackageNames.get(position));
                        showLetter(letter);
                        int newPosition = letterPosition.get(letter);
                        recyclerView.smoothScrollToPosition(newPosition);
                        return true;
                    }
                }
                return false;
            }

            @Override
            public void onTouchEvent(@NonNull RecyclerView rv, @NonNull MotionEvent e) {
            }

            @Override
            public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) {
            }
        });

        recyclerView.setOnScrollChangeListener((v, scrollX, scrollY, oldScrollX, oldScrollY) -> {
            View view = recyclerView.findChildViewUnder(letter.getWidth() / 2, letter.getHeight() / 2);
            if (view != null) {
                int position = recyclerView.getChildAdapterPosition(view);
                String letter = getFirstLetter(sortedPackageNames.get(position));
                showLetter(letter);
            }
        });
    }

    private void getPackageNames() {
        PackageManager pm = getPackageManager();
        List<ApplicationInfo> apps = pm.getInstalledApplications(0);
        for (ApplicationInfo app : apps) {
            packageNames.add(app.packageName);
        }
    }

    private void sortPackageNames() {
        HanziToPinyin hanziToPinyin = new HanziToPinyin();
        List<String> pinyinPackageNames = new ArrayList<>();
        for (String packageName : packageNames) {
            String name = null;
            try {
                name = getPackageManager().getApplicationLabel(getPackageManager().getApplicationInfo(packageName, PackageManager.GET_META_DATA)).toString();
            } catch (PackageManager.NameNotFoundException e) {
                e.printStackTrace();
            }
            String pinyin = hanziToPinyin.getPinyin(name);
            pinyinPackageNames.add(pinyin + "#" + packageName);
        }
        Collections.sort(pinyinPackageNames);
        for (String pinyinPackageName : pinyinPackageNames) {
            String packageName = pinyinPackageName.substring(pinyinPackageName.indexOf("#") + 1);
            sortedPackageNames.add(packageName);
        }
    }

    private void initLetterPosition() {
        String lastLetter = null;
        for (int i = 0; i < sortedPackageNames.size(); i++) {
            String letter = getFirstLetter(sortedPackageNames.get(i));
            if (!letter.equals(lastLetter)) {
                letterPosition.put(letter, i);
                lastLetter = letter;
            }
        }
    }

    private String getFirstLetter(String s) {
        String pinyin = HanziToPinyin.getInstance().getPinyin(s);
        String firstLetter = pinyin.substring(0, 1);
        if (!firstLetter.matches("[A-Za-z]")) {
            firstLetter = "#";
        }
        return firstLetter.toUpperCase();
    }

    private void showLetter(String letter) {
        this.letter.setText(letter);
        this.letter.setVisibility(View.VISIBLE);
        new Handler().postDelayed(() -> this.letter.setVisibility(View.GONE), 1000);
    }

    private class ApplicationAdapter extends RecyclerView.Adapter<ApplicationViewHolder> {
        private List<String> packageNames;

        public ApplicationAdapter(List<String> packageNames) {
            this.packageNames = packageNames;
        }

        @NonNull
        @Override
        public ApplicationViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
            View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_application, parent, false);
            return new ApplicationViewHolder(view);
        }

        @Override
        public void onBindViewHolder(@NonNull ApplicationViewHolder holder, int position) {
            String packageName = packageNames.get(position);
            holder.bind(packageName);
        }

        @Override
        public int getItemCount() {
            return packageNames.size();
        }
    }
}

在`MainActivity`中，我们首先获取所有应用程序的包名和应用程序名称，并将其存储在一个列表中。然后，我们按照首字母对包名进行排序，并初始化字母与位置的映射表。接下来，我们创建一个自定义RecyclerView.Adapter，在其中实现适当的方法。最后，我们实现了字幕条索引，并在RecyclerView上添加了一个FastScroller，使用`setOnTouchLetterChangeListenner`方法来监听字母条的触摸事件。

注意事项：

1. 代码中使用了androidx库。
2. 需要在`AndroidManifest.xml`文件中添加`<uses-permission android:name="android.permission.GET_TASKS" />`权限。