diff --git a/MoreTeapots/app/build.gradle b/MoreTeapots/app/build.gradle
index 78a985de..85aca5e5 100644
--- a/MoreTeapots/app/build.gradle
+++ b/MoreTeapots/app/build.gradle
@@ -14,39 +14,39 @@ if (propertiesFile.exists()) {
 model {
     android {
         compileSdkVersion = 23
-        buildToolsVersion = "23.0.2"
+        buildToolsVersion = '23.0.2'
 
         defaultConfig {
-            applicationId    = "com.sample.moreteapots"
+            applicationId    = 'com.sample.moreteapots'
             minSdkVersion.apiLevel    = 17
             targetSdkVersion.apiLevel = 22
         }
         ndk {
-            moduleName = "MoreTeapotsNativeActivity"
+            moduleName = 'MoreTeapotsNativeActivity'
             // temporarily use gcc since clang does not work on windows (*)
             // also clang warning about inline, so could not use -Wall, -Werror
             // toolchain = "clang"
-            stl       = "gnustl_static"
-            cppFlags.addAll(["-I" + "${ndkDir}/sources/android/cpufeatures",
-                             "-I" + file("src/main/jni/ndk_helper")])
-            cppFlags.addAll(["-std=c++11", "-Werror", "-Wall",
-                             "-fno-exceptions", "-fno-rtti"])
-            ldLibs.addAll(["android", "log", "EGL", "GLESv2","atomic"])
+            stl       = 'gnustl_static'
+            cppFlags.addAll(['-I' + "${ndkDir}/sources/android/cpufeatures",
+                             '-I' + file('src/main/jni/ndk_helper')])
+            cppFlags.addAll(['-std=c++11', '-Werror', '-Wall',
+                             '-fno-exceptions', '-fno-rtti'])
+            ldLibs.addAll(['android', 'log', 'EGL', 'GLESv2','atomic'])
         }
         // Turn on hard float support in armeabi-v7a
         abis {
-            create("armeabi-v7a") {
-                cppFlags.addAll(["-mhard-float", "-D_NDK_MATH_NO_SOFTFP=1",
-                                 "-mfloat-abi=hard"])
-                ldLibs.add("m_hard")
-                ldFlags.add("-Wl,--no-warn-mismatch")
+            create('armeabi-v7a') {
+                cppFlags.addAll(['-mhard-float', '-D_NDK_MATH_NO_SOFTFP=1',
+                                 '-mfloat-abi=hard'])
+                ldLibs.add('m_hard')
+                ldFlags.add('-Wl,--no-warn-mismatch')
             }
         }
         sources {
             main {
                 jni {
                     dependencies {
-                        project ":nativeactivity" linkage "static"
+                        project ':nativeactivity' linkage 'static'
                     }
                     source {
                         srcDirs 'src/main/jni'
diff --git a/MoreTeapots/nativeactivity/build.gradle b/MoreTeapots/nativeactivity/build.gradle
index 8407f293..84409776 100644
--- a/MoreTeapots/nativeactivity/build.gradle
+++ b/MoreTeapots/nativeactivity/build.gradle
@@ -11,17 +11,17 @@ if (propertiesFile.exists()) {
 model {
     android {
         compileSdkVersion = 23
-        buildToolsVersion = "23.0.2"
+        buildToolsVersion = '23.0.2'
         defaultConfig.with {
             minSdkVersion.apiLevel = 9
             targetSdkVersion.apiLevel = 23
             versionCode = 1
-            versionName = "0.0.1"
+            versionName = '0.0.1'
         }
         ndk {
-            moduleName = "native-activity"
-            ldLibs.addAll(["log", "android"])
-            ldFlags.add("-c")
+            moduleName = 'native-activity'
+            ldLibs.addAll(['log', 'android'])
+            ldFlags.add('-c')
         }
         sources {
             main {
diff --git a/Teapot/app/build.gradle b/Teapot/app/build.gradle
index 9fadc66e..0a1874ed 100644
--- a/Teapot/app/build.gradle
+++ b/Teapot/app/build.gradle
@@ -14,39 +14,39 @@ if (propertiesFile.exists()) {
 model {
     android {
         compileSdkVersion = 23
-        buildToolsVersion = "23.0.2"
+        buildToolsVersion = '23.0.2'
 
         defaultConfig {
-            applicationId = "com.sample.teapot"
+            applicationId = 'com.sample.teapot'
             minSdkVersion.apiLevel = 17
             targetSdkVersion.apiLevel = 22
         }
         ndk {
-            moduleName = "TeapotNativeActivity"
+            moduleName = 'TeapotNativeActivity'
             // temporarily use gcc since clang does not work on windows (*)
             // also clang warning about inline, so could not use -Wall, -Werror
             // toolchain = "clang"
-            stl       = "gnustl_static"
-            cppFlags.addAll(["-I" + "${ndkDir}/sources/android/cpufeatures",
-                             "-I" + file("src/main/jni/ndk_helper")])
-            cppFlags.addAll(["-std=c++11", "-Werror", "-Wall",
-                             "-fno-exceptions", "-fno-rtti"])
-            ldLibs.addAll(["android", "log", "EGL", "GLESv2","atomic"])
+            stl       = 'gnustl_static'
+            cppFlags.addAll(['-I' + "${ndkDir}/sources/android/cpufeatures",
+                             '-I' + file('src/main/jni/ndk_helper')])
+            cppFlags.addAll(['-std=c++11', '-Werror', '-Wall',
+                             '-fno-exceptions', '-fno-rtti'])
+            ldLibs.addAll(['android', 'log', 'EGL', 'GLESv2','atomic'])
         }
         // Turn on hard float support in armeabi-v7a
         abis {
-            create("armeabi-v7a") {
-                cppFlags.addAll(["-mhard-float", "-D_NDK_MATH_NO_SOFTFP=1",
-                                 "-mfloat-abi=hard"])
-                ldLibs.add("m_hard")
-                ldFlags.add("-Wl,--no-warn-mismatch")
+            create('armeabi-v7a') {
+                cppFlags.addAll(['-mhard-float', '-D_NDK_MATH_NO_SOFTFP=1',
+                                 '-mfloat-abi=hard'])
+                ldLibs.add('m_hard')
+                ldFlags.add('-Wl,--no-warn-mismatch')
             }
         }
         sources {
             main {
                 jni {
                     dependencies {
-                        project ":nativeactivity" linkage "static"
+                        project ':nativeactivity' linkage 'static'
                     }
                     source {
                         srcDirs 'src/main/jni'
diff --git a/Teapot/nativeactivity/build.gradle b/Teapot/nativeactivity/build.gradle
index 8407f293..84409776 100644
--- a/Teapot/nativeactivity/build.gradle
+++ b/Teapot/nativeactivity/build.gradle
@@ -11,17 +11,17 @@ if (propertiesFile.exists()) {
 model {
     android {
         compileSdkVersion = 23
-        buildToolsVersion = "23.0.2"
+        buildToolsVersion = '23.0.2'
         defaultConfig.with {
             minSdkVersion.apiLevel = 9
             targetSdkVersion.apiLevel = 23
             versionCode = 1
-            versionName = "0.0.1"
+            versionName = '0.0.1'
         }
         ndk {
-            moduleName = "native-activity"
-            ldLibs.addAll(["log", "android"])
-            ldFlags.add("-c")
+            moduleName = 'native-activity'
+            ldLibs.addAll(['log', 'android'])
+            ldFlags.add('-c')
         }
         sources {
             main {
diff --git a/audio-echo/app/build.gradle b/audio-echo/app/build.gradle
index f0dec926..94e62d11 100644
--- a/audio-echo/app/build.gradle
+++ b/audio-echo/app/build.gradle
@@ -3,20 +3,20 @@ apply plugin: 'com.android.model.application'
 model {
     android {
         compileSdkVersion = 23
-        buildToolsVersion = "23.0.2"
+        buildToolsVersion = '23.0.2'
 
         defaultConfig {
-            applicationId="com.google.sample.echo"
+            applicationId='com.google.sample.echo'
             minSdkVersion.apiLevel = 17
             targetSdkVersion.apiLevel = 22
             versionCode = 1
-            versionName = "1.0"
+            versionName = '1.0'
         }
         ndk {
-            moduleName = "echo"
+            moduleName = 'echo'
             //toolchain  = "clang"
-            stl        = "c++_static"
-            cppFlags.add("-std=c++11")
+            stl        = 'c++_static'   //std::mutex not in gnustl_static
+            cppFlags.add('-std=c++11')
             ldLibs.addAll(['android', 'log', 'OpenSLES', 'atomic'])
         }
         buildTypes {
diff --git a/endless-tunnel/app/build.gradle b/endless-tunnel/app/build.gradle
index b0d6e3b3..9813d3fb 100644
--- a/endless-tunnel/app/build.gradle
+++ b/endless-tunnel/app/build.gradle
@@ -19,36 +19,36 @@ apply plugin: 'com.android.model.application'
 model {
     android {
         compileSdkVersion = 23
-        buildToolsVersion = "23.0.2"
+        buildToolsVersion = '23.0.2'
 
         defaultConfig {
             minSdkVersion.apiLevel    = 9
             targetSdkVersion.apiLevel = 23
             versionCode     =  1
-            versionName     = "1.0"
+            versionName     = '1.0'
        }
         ndk {
-            moduleName = "game"
-            stl        = "gnustl_static" // recommending gnustl_static/gnustl_shared for android
-            cppFlags.addAll(["-std=c++11", // glm could not take -Wall -Werror
-                             "-D GLM_FORCE_SIZE_T_LENGTH", "-D GLM_FORCE_RADIANS",
-                             "-I" + file("src/main/jni"),
-                             "-I" + file("src/main/jni/data")])
-            ldLibs.addAll(["android", "EGL", "GLESv2", "OpenSLES", "log"])
+            moduleName = 'game'
+            stl        = 'gnustl_static' // recommending gnustl_static/gnustl_shared for android
+            cppFlags.addAll(['-std=c++11', // glm could not take -Wall -Werror
+                             '-D GLM_FORCE_SIZE_T_LENGTH', '-D GLM_FORCE_RADIANS',
+                             '-I' + file('src/main/jni'),
+                             '-I' + file('src/main/jni/data')])
+            ldLibs.addAll(['android', 'EGL', 'GLESv2', 'OpenSLES', 'log'])
         }
         // Turn on hard float support in armeabi-v7a
         abis {
-            create("armeabi-v7a") {
-                cppFlags.addAll(["-mhard-float", "-D_NDK_MATH_NO_SOFTFP=1", "-mfloat-abi=hard"])
-                ldLibs.add("m_hard")
-                ldFlags.add("-Wl,--no-warn-mismatch")
+            create('armeabi-v7a') {
+                cppFlags.addAll(['-mhard-float', '-D_NDK_MATH_NO_SOFTFP=1', '-mfloat-abi=hard'])
+                ldLibs.add('m_hard')
+                ldFlags.add('-Wl,--no-warn-mismatch')
             }
         }
         sources {
             main {
                 jni {
                     dependencies {
-                        project ":nativeactivity" linkage "static"
+                        project ':nativeactivity' linkage 'static'
                     }
                 }
             }
diff --git a/endless-tunnel/nativeactivity/build.gradle b/endless-tunnel/nativeactivity/build.gradle
index 8407f293..84409776 100644
--- a/endless-tunnel/nativeactivity/build.gradle
+++ b/endless-tunnel/nativeactivity/build.gradle
@@ -11,17 +11,17 @@ if (propertiesFile.exists()) {
 model {
     android {
         compileSdkVersion = 23
-        buildToolsVersion = "23.0.2"
+        buildToolsVersion = '23.0.2'
         defaultConfig.with {
             minSdkVersion.apiLevel = 9
             targetSdkVersion.apiLevel = 23
             versionCode = 1
-            versionName = "0.0.1"
+            versionName = '0.0.1'
         }
         ndk {
-            moduleName = "native-activity"
-            ldLibs.addAll(["log", "android"])
-            ldFlags.add("-c")
+            moduleName = 'native-activity'
+            ldLibs.addAll(['log', 'android'])
+            ldFlags.add('-c')
         }
         sources {
             main {
diff --git a/hello-gl2/app/build.gradle b/hello-gl2/app/build.gradle
index 7827d017..790251c7 100644
--- a/hello-gl2/app/build.gradle
+++ b/hello-gl2/app/build.gradle
@@ -3,24 +3,24 @@ apply plugin: 'com.android.model.application'
 model {
     android {
         compileSdkVersion = 23
-        buildToolsVersion = "23.0.2"
+        buildToolsVersion = '23.0.2'
         defaultConfig {
-            applicationId    = "com.android.gl2jni"
+            applicationId    = 'com.android.gl2jni'
             minSdkVersion.apiLevel    = 5
             targetSdkVersion.apiLevel = 23
         }
         ndk {
-            moduleName = "gl2jni"
-            stl        = "gnustl_static"
-            cppFlags.addAll(["-std=c++11","-Wall", "-Werror"])
-            ldLibs.addAll(["log", "GLESv2"])
+            moduleName = 'gl2jni'
+            stl        = 'gnustl_static'
+            cppFlags.addAll(['-std=c++11','-Wall', '-Werror'])
+            ldLibs.addAll(['log', 'GLESv2'])
         }
         // Turn on hard float support in armeabi-v7a
         abis {
-            create("armeabi-v7a") {
-                cppFlags.addAll(["-mhard-float", "-D_NDK_MATH_NO_SOFTFP=1", "-mfloat-abi=hard"])
-                ldLibs.add("m_hard")
-                ldFlags.add("-Wl,--no-warn-mismatch")
+            create('armeabi-v7a') {
+                cppFlags.addAll(['-mhard-float', '-D_NDK_MATH_NO_SOFTFP=1', '-mfloat-abi=hard'])
+                ldLibs.add('m_hard')
+                ldFlags.add('-Wl,--no-warn-mismatch')
             }
         }
         buildTypes {
diff --git a/native-plasma/app/build.gradle b/native-plasma/app/build.gradle
index 22bf0bb0..77dee263 100644
--- a/native-plasma/app/build.gradle
+++ b/native-plasma/app/build.gradle
@@ -3,23 +3,22 @@ apply plugin: 'com.android.model.application'
 model {
     android {
         compileSdkVersion = 23
-        buildToolsVersion = "23.0.2"
+        buildToolsVersion = '23.0.2'
 
         defaultConfig {
-            applicationId="com.example.native_plasma"
+            applicationId='com.example.native_plasma'
             minSdkVersion.apiLevel   = 9
             targetSdkVersion.apiLevel = 23
         }
         ndk {
-            moduleName = "native-plasma"
-            CFlags.add("-I" + file("src/main/jni/native_app_glue"))
-            ldLibs.addAll(["m", "log","android"])
+            moduleName = 'native-plasma'
+            ldLibs.addAll(['m', 'log','android'])
         }
         sources {
             main {
                 jni {
                     dependencies {
-                        project ":nativeactivity" linkage "static"
+                        project ':nativeactivity' linkage 'static'
                     }
                 }
             }
diff --git a/native-plasma/nativeactivity/build.gradle b/native-plasma/nativeactivity/build.gradle
index 8407f293..84409776 100644
--- a/native-plasma/nativeactivity/build.gradle
+++ b/native-plasma/nativeactivity/build.gradle
@@ -11,17 +11,17 @@ if (propertiesFile.exists()) {
 model {
     android {
         compileSdkVersion = 23
-        buildToolsVersion = "23.0.2"
+        buildToolsVersion = '23.0.2'
         defaultConfig.with {
             minSdkVersion.apiLevel = 9
             targetSdkVersion.apiLevel = 23
             versionCode = 1
-            versionName = "0.0.1"
+            versionName = '0.0.1'
         }
         ndk {
-            moduleName = "native-activity"
-            ldLibs.addAll(["log", "android"])
-            ldFlags.add("-c")
+            moduleName = 'native-activity'
+            ldLibs.addAll(['log', 'android'])
+            ldFlags.add('-c')
         }
         sources {
             main {
diff --git a/sensor-graph/app/build.gradle b/sensor-graph/app/build.gradle
index 3e5537f4..ffd681d1 100644
--- a/sensor-graph/app/build.gradle
+++ b/sensor-graph/app/build.gradle
@@ -3,21 +3,21 @@ apply plugin: 'com.android.model.application'
 model {
     android {
         compileSdkVersion = 23
-        buildToolsVersion = "23.0.2"
+        buildToolsVersion = '23.0.2'
 
         defaultConfig {
-            applicationId    = "com.android.sensorgraph"
+            applicationId    = 'com.android.sensorgraph'
             minSdkVersion.apiLevel    = 8
             targetSdkVersion.apiLevel = 23
         }
         ndk {
-            moduleName = "sensorgraph"
+            moduleName = 'sensorgraph'
             // for clang to build, need to remove mips or remove -Werror
             // toolchain = 'clang'
             // abiFilters.addAll(['armeabi','armeabi-v7a', 'arm64-v8a', 'x86', 'x86-64'])
-            stl        = "gnustl_static"
+            stl        = 'gnustl_static'
             cppFlags.addAll(['-std=c++11','-Wall', '-Werror'])
-            ldLibs.addAll(["log", "GLESv2", "android"])
+            ldLibs.addAll([ 'android', 'log', 'GLESv2'])
         }
         buildTypes {
             release {