Call an Android API

battery.lucent.ts

import { PLATFORM } from "lucent:platform";
import { BatteryManager } from "lucent:android/android.os";
import { appContext } from "lucent:android";
import { error } from "lucent:core";

export async function isCharging(): Promise<boolean> {
  if (PLATFORM === "android") {
    const manager = appContext().getSystemService(BatteryManager);
    if (!manager) throw error("E_NO_BATTERY", "BatteryManager isn't available");
    return manager.charging;
  } else {
    throw error("E_UNSUPPORTED", "Only Android is implemented");
  }
}

See the C++

iOS

m_battery.cpp

// Generated by Lucent from battery.lucent.ts. Do not edit.
#include "m_battery.h"

#pragma push_macro("isCharging")
#undef isCharging

namespace lucent_app {

lucent::Promise<bool> m_battery::isCharging() {
#line 7 "battery.lucent.ts"
  {
#line 12 "battery.lucent.ts"
    lucent::Error v2_ = lucent::withSite(lucent::errorWithCode(LUCENT_STR("E_UNSUPPORTED"), LUCENT_STR("Only Android is implemented")), __FILE__, __LINE__, "isCharging");
    lucent::throwError(v2_);
  }
  co_return []() -> bool {
    lucent::unreachable();
  }();
}

void m_battery::init() {
}

}  // namespace lucent_app

#pragma pop_macro("isCharging")

Android

m_battery.cpp

// Generated by Lucent from battery.lucent.ts. Do not edit.
#include <lucent/platform/android.h>
#include "m_battery.h"

#pragma push_macro("isCharging")
#undef isCharging
#pragma push_macro("manager")
#undef manager

namespace lucent_app {

lucent::Promise<bool> m_battery::isCharging() {
#line 7 "battery.lucent.ts"
  {
#line 8 "battery.lucent.ts"
    lucent::NativeRef v0_ = lucent::jni::appContext();
    lucent::Opt<lucent::NativeRef> manager = [&]() -> lucent::Opt<lucent::NativeRef> {
      JNIEnv* env = lucent::jni::env();
      auto recv_ = v0_;
      lucent::jni::LocalFrame frame_(env);
      static jclass cls_ = lucent::jni::findClass("android/content/Context");
      static auto id_ = lucent::jni::method(cls_, "getSystemService", "(Ljava/lang/Class;)Ljava/lang/Object;");
      auto r_ = env->CallObjectMethod(lucent::jni::unwrap(recv_), id_, lucent::jni::findClass("android/os/BatteryManager"));
      lucent::jni::check(env);
      return lucent::jni::wrapOpt(env, r_);
    }();
#line 9 "battery.lucent.ts"
    bool v4_ = !lucent::truthy(manager);
    if (v4_) {
      lucent::Error v7_ = lucent::withSite(lucent::errorWithCode(LUCENT_STR("E_NO_BATTERY"), LUCENT_STR("BatteryManager isn't available")), __FILE__, __LINE__, "isCharging");
      lucent::throwError(v7_);
    }
#line 10 "battery.lucent.ts"
    lucent::NativeRef v9_ = manager.value();
    co_return [&]() -> bool {
      JNIEnv* env = lucent::jni::env();
      auto recv_ = v9_;
      lucent::jni::LocalFrame frame_(env);
      static jclass cls_ = lucent::jni::findClass("android/os/BatteryManager");
      static auto id_ = lucent::jni::method(cls_, "isCharging", "()Z");
      auto r_ = env->CallBooleanMethod(lucent::jni::unwrap(recv_), id_);
      lucent::jni::check(env);
      return r_ == JNI_TRUE;
    }();
  }
}

void m_battery::init() {
}

}  // namespace lucent_app

#pragma pop_macro("manager")
#pragma pop_macro("isCharging")

• Import from lucent:android/<package>: any package of android.jar, or of the app's Gradle dependencies.
• appContext() from lucent:android is the app's Context. currentActivity() is the Activity in front, or null: use it now, inside main(), rather than keep it.
• startActivityForResult() and requestPermissions() ask from the Activity in front and resolve with the answer. onActivityEvent() reports the Activities' lifecycle.
• A Class<T> parameter takes the class itself: getSystemService(BatteryManager) returns a BatteryManager | null.
• isCharging() is also the property charging, as Kotlin makes properties of getters.
• References the SDK doesn't mark @NonNull are T | null, so check them.

A Java exception becomes a thrown error whose code is the exception's class. Nested classes join with _: Build.VERSION is Build_VERSION. SDK types has every rule.

Caution

APIs newer than API 24 compile only behind a version check. See Check the OS version.