在Expo中，推送令牌是用于向设备发送推送通知的重要标识符。在Android独立应用程序中，Expo推送令牌可能没有被正确创建，导致推送通知无法正常工作。

以下是在Android独立应用程序中创建Expo推送令牌的示例代码：

1. 在app/build.gradle文件中添加以下依赖项：

implementation 'com.google.android.gms:play-services-gcm:12.0.1'
implementation 'com.google.firebase:firebase-messaging:12.0.1'

2. 创建PushNotification.java类，并添加以下代码：

import android.content.Context;

import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GoogleApiAvailability;
import com.google.android.gms.common.GooglePlayServicesUtil;

import io.expo.client.BuildConfig;
import io.expo.client.ExpoAndroidNotificationsDelegate;
import io.expo.client.ExponentManifest;
import io.expo.client.kernel.KernelConstants;
import versioned.host.exp.exponent.Constants;
import versioned.host.exp.exponent.ExponentApplication;

public class PushNotification {
  public static void register(Context context) {
    if (!ExpoAndroidNotificationsDelegate.isInitialized()) {
      ExponentApplication application = (ExponentApplication) context.getApplicationContext();
      ExponentManifest manifest = application.getManifest();
      String experienceId = manifest.optString(ExponentManifest.MANIFEST_ID_KEY);

      if (experienceId != null && experienceId.length() > 0) {
        if (GoogleApiAvailability.getInstance().isGooglePlayServicesAvailable(context) == ConnectionResult.SUCCESS) {
          ExpoAndroidNotificationsDelegate.init(application, experienceId, manifest);
        } else {
          // Handle error
        }
      } else {
        // Handle error
      }
    }
  }

  public static void unregister(Context context) {
    if (ExpoAndroidNotificationsDelegate.isInitialized()) {
      ExpoAndroidNotificationsDelegate delegate = ExpoAndroidNotificationsDelegate.getInstance();

      if (delegate != null) {
        delegate.stop();

        ExpoAndroidNotificationsDelegate.unpinDeviceToken(context);
        ExpoAndroidNotificationsDelegate.release();