Android新手求助：如何在RecyclerView中获取带GMT的时区？

Hey there! As someone who’s worked with Android RecyclerViews and time zone handling, let me walk you through a simple, step-by-step way to get those GMT-tagged time zones and show them in a RecyclerView.

Step 1: Fetch All GMT Time Zones #

First, we need to grab all time zones that have the GMT identifier. Android leverages the Java TimeZone class, which has a handy method to get all available time zone IDs. We’ll filter these to keep only the ones starting with "GMT" (since those are formatted like GMT+03:00 or GMT-05:00).

Here’s the code to do that:

// Initialize a list to hold our GMT time zones
List<String> gmtTimeZones = new ArrayList<>();

// Get all available time zone IDs
String[] allTimeZoneIds = TimeZone.getAvailableIDs();

// Filter for GMT-only entries
for (String id : allTimeZoneIds) {
    if (id.startsWith("GMT")) {
        gmtTimeZones.add(id);
    }
}

// Optional: Sort the list to arrange time zones from west to east
Collections.sort(gmtTimeZones);

Step 2: Create a RecyclerView Adapter #

Next, we need an adapter to connect our time zone list to the RecyclerView. First, make a simple layout for each list item (res/layout/item_time_zone.xml):

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/tv_time_zone"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:paddingVertical="12dp"
    android:paddingHorizontal="16dp"
    android:textSize="16sp"/>

Then create the adapter class:

public class TimeZoneAdapter extends RecyclerView.Adapter<TimeZoneAdapter.TimeZoneViewHolder> {

    private List<String> mTimeZoneList;

    // Constructor to pass in our time zone data
    public TimeZoneAdapter(List<String> timeZoneList) {
        mTimeZoneList = timeZoneList;
    }

    @NonNull
    @Override
    public TimeZoneViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        // Inflate the item layout
        View itemView = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.item_time_zone, parent, false);
        return new TimeZoneViewHolder(itemView);
    }

    @Override
    public void onBindViewHolder(@NonNull TimeZoneViewHolder holder, int position) {
        // Bind the time zone ID to the TextView
        String timeZoneId = mTimeZoneList.get(position);
        holder.tvTimeZone.setText(timeZoneId);

        // Optional: Show a friendlier display name alongside GMT (e.g., GMT+01:00 (CET))
        // TimeZone timeZone = TimeZone.getTimeZone(timeZoneId);
        // String displayName = timeZone.getDisplayName(false, TimeZone.SHORT);
        // holder.tvTimeZone.setText(timeZoneId + " (" + displayName + ")");
    }

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

    // ViewHolder class to hold references to our views
    public static class TimeZoneViewHolder extends RecyclerView.ViewHolder {
        TextView tvTimeZone;

        public TimeZoneViewHolder(@NonNull View itemView) {
            super(itemView);
            tvTimeZone = itemView.findViewById(R.id.tv_time_zone);
        }
    }
}

Step 3: Set Up the RecyclerView in Your Activity/Fragment #

Finally, wire everything together in your Activity or Fragment. Make sure you have a RecyclerView in your layout (res/layout/activity_main.xml for example):

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

Then initialize it in your code:

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

    // Get reference to the RecyclerView
    RecyclerView recyclerView = findViewById(R.id.recycler_time_zones);

    // Use a LinearLayoutManager to show items in a vertical list
    recyclerView.setLayoutManager(new LinearLayoutManager(this));

    // Fetch the GMT time zones (from Step 1)
    List<String> gmtTimeZones = new ArrayList<>();
    String[] allTimeZoneIds = TimeZone.getAvailableIDs();
    for (String id : allTimeZoneIds) {
        if (id.startsWith("GMT")) {
            gmtTimeZones.add(id);
        }
    }
    Collections.sort(gmtTimeZones);

    // Attach the adapter to the RecyclerView
    TimeZoneAdapter adapter = new TimeZoneAdapter(gmtTimeZones);
    recyclerView.setAdapter(adapter);
}

Extra Tips #

• If you need to get the current device's GMT time zone, use TimeZone.getDefault().getID() — this will return something like GMT+02:00 depending on the device's location.
• The optional code in onBindViewHolder lets you display a more user-friendly name (like "CET" for Central European Time) alongside the GMT offset, which can make the list more useful for users.

内容的提问来源于stack exchange，提问作者Pooja SWS