Moving the FhirEngine creation in the Application

example/src/main/java/com/google/fhirengine/example/FhirApplication.kt

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2020 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http:https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.fhirengine.example
+
+import android.app.Application
+import android.content.Context
+import androidx.work.Constraints
+import ca.uhn.fhir.context.FhirContext
+import com.google.fhirengine.FhirEngine
+import com.google.fhirengine.FhirEngineBuilder
+import com.google.fhirengine.example.api.HapiFhirService.Companion.create
+import com.google.fhirengine.example.data.HapiFhirResourceDataSource
+import com.google.fhirengine.sync.FhirDataSource
+import com.google.fhirengine.sync.SyncConfiguration
+import com.google.fhirengine.sync.SyncData
+import org.hl7.fhir.r4.model.ResourceType
+import java.util.ArrayList
+
+class FhirApplication : Application() {
+
+ // only initiate the FhirEngine when used for the first time, not when the app is created
+ private val fhirEngine: FhirEngine by lazy { constructFhirEngine() }
+
+ private fun constructFhirEngine(): FhirEngine {
+ val parser = FhirContext.forR4().newJsonParser()
+ val service = create(parser)
+ val params = mutableMapOf("address-country" to "United States")
+ val syncData: MutableList<SyncData> = ArrayList()
+ syncData.add(SyncData(ResourceType.Patient, params))
+ val configuration = SyncConfiguration(syncData, Constraints.Builder().build(), false)
+ val dataSource: FhirDataSource = HapiFhirResourceDataSource(service)
+ return FhirEngineBuilder(configuration, dataSource, this).build()
+ }
+
+ companion object {
+ @JvmStatic
+ fun fhirEngine(context: Context) =
+ (context.applicationContext as FhirApplication).fhirEngine
+ }
+}

example/src/main/java/com/google/fhirengine/example/MainActivity.java

@@ -70,16 +70,7 @@ protected void onCreate(Bundle savedInstanceState) {
  expressionInput = findViewById(R.id.expression_input);
  evaluationResultTextView = findViewById(R.id.evaluate_result);
 
- IParser parser = FhirContext.forR4().newJsonParser();
- HapiFhirService service = HapiFhirService.Companion.create(parser);
- Map<String, String> params = new HashMap();
- params.put("address-country", "United States");
- List<SyncData> syncData = new ArrayList<>();
- syncData.add(new SyncData(ResourceType.Patient, params));
- SyncConfiguration configuration =
- new SyncConfiguration(syncData, new Constraints.Builder().build(), false);
- FhirDataSource dataSource = new HapiFhirResourceDataSource(service);
- fhirEngine = new FhirEngineBuilder(configuration, dataSource, this).build();
+ fhirEngine = FhirApplication.fhirEngine(this);
 
  MainActivityViewModel viewModel =
  new ViewModelProvider(this, new MainActivityViewModelFactory(fhirEngine))

fhirengine/src/main/java/com/google/fhirengine/FhirEngineBuilder.kt

@@ -23,7 +23,7 @@ import com.google.fhirengine.sync.SyncConfiguration
 /**
  * The builder for [FhirEngine] instance
  */
-class FhirEngineBuilder internal constructor(
+class FhirEngineBuilder constructor(
  syncConfiguration: SyncConfiguration,
  dataSource: FhirDataSource,
  context: Context