build.gradle improvements

android/build.gradle

@@ -1,21 +1,18 @@
 apply plugin: 'com.android.library'
 
-def DEFAULT_COMPILE_SDK_VERSION             = 25
-def DEFAULT_BUILD_TOOLS_VERSION             = "25.0.3"
-def DEFAULT_TARGET_SDK_VERSION              = 25
+def safeExtGet(prop, fallback) {
+    rootProject.ext.has(prop) ? rootProject.ext.get(prop) : fallback
+}
 
 android {
-    compileSdkVersion project.hasProperty('compileSdkVersion') ? project.compileSdkVersion : DEFAULT_COMPILE_SDK_VERSION
-    buildToolsVersion project.hasProperty('buildToolsVersion') ? project.buildToolsVersion : DEFAULT_BUILD_TOOLS_VERSION
+    compileSdkVersion safeExtGet('compileSdkVersion', 25)
+    buildToolsVersion safeExtGet('buildToolsVersion', "25.0.3")
 
     defaultConfig {
-        minSdkVersion 16
-        targetSdkVersion project.hasProperty('targetSdkVersion') ? project.targetSdkVersion : DEFAULT_TARGET_SDK_VERSION
-        versionCode 1
-        versionName "1.0"
+        minSdkVersion safeExtGet('minSdkVersion', 16)
+        targetSdkVersion safeExtGet('targetSdkVersion', 25)
 
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
-
     }
     buildTypes {
         release {
@@ -26,10 +23,9 @@ android {
 }
 
 dependencies {
-    compile fileTree(include: ['*.jar'], dir: 'libs')
-    compile 'com.facebook.react:react-native:+'
-    compile 'com.henninghall.android:NumberPickerView:1.1.1'
-    compile 'org.apache.commons:commons-lang3:3.6'
-    compile group: 'net.time4j', name: 'time4j-android', version: '4.2-2018i'
-
+    implementation fileTree(include: ['*.jar'], dir: 'libs')
+    implementation 'com.facebook.react:react-native:+'
+    implementation 'com.henninghall.android:NumberPickerView:1.1.1'
+    implementation 'org.apache.commons:commons-lang3:3.6'
+    implementation group: 'net.time4j', name: 'time4j-android', version: '4.2-2018i'
 }