HistorySingleActivity报错：cannot resolve symbol polylines求助

Hey there, sorry to hear you're stuck on this frustrating error while building your ride history app—let's break down the most likely causes and fixes step by step.

1. Missing or Mismatched Map SDK Dependencies #

If you're using Google Maps to draw route polylines, the Polyline class lives in the Google Play Services Maps SDK. First, double-check your module-level build.gradle to ensure you've added the correct dependency:

dependencies {
    // Use the latest stable version of the Maps SDK
    implementation 'com.google.android.gms:play-services-maps:18.1.0'
}

Don't forget to sync your Gradle project (click the "Sync Now" prompt in Android Studio) after making changes—unsynced dependencies are a super common culprit for missing symbols.

2. Incorrect or Missing Import Statements #

Even if you think you've imported everything, it's worth verifying:

• For Google Maps Polyline and PolylineOptions, you need these exact imports:

import com.google.android.gms.maps.model.Polyline;
import com.google.android.gms.maps.model.PolylineOptions;

• Make sure you're not mixing up classes from other map libraries (like Baidu or Amap)—their Polyline classes have completely different package names, which would cause this error.

3. Typos or Invalid Method/Variable Names #

Java is case-sensitive, so a tiny typo can break everything:

• If you wrote polylines (lowercase) instead of Polyline (uppercase) when declaring an object, that's a problem.
• Double-check if you're calling a non-existent method like googleMap.polylines()—the correct method for adding a polyline to a Google Map is googleMap.addPolyline().

Here's a quick example of the correct usage for reference:

@Override
public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;

    // Define your route points
    PolylineOptions routeOptions = new PolylineOptions()
            .add(new LatLng(37.7749, -122.4194))
            .add(new LatLng(34.0522, -118.2437))
            .color(Color.RED)
            .width(6f);

    // Add the polyline to the map
    Polyline rideRoute = mMap.addPolyline(routeOptions);
}

4. ProGuard Obfuscation Breaking Map Classes #

If you have code obfuscation enabled, check your proguard-rules.pro file—you might be accidentally obfuscating the Google Maps classes. Add these rules to keep them intact:

-keep class com.google.android.gms.maps.** { *; }
-keep interface com.google.android.gms.maps.** { *; }

Rebuild your project after updating the rules.

5. Android Studio Cache Glitches #

Sometimes the IDE's cache gets corrupted, leading to false errors. Try these steps:

• Go to File -> Invalidate Caches..., select Invalidate and Restart, and let Android Studio reboot.
• Clean and rebuild your project: Build -> Clean Project followed by Build -> Rebuild Project.

If none of these fix the issue, sharing the specific lines of code where you're using polylines would help narrow things down even further!

内容的提问来源于stack exchange，提问作者Viva