Compile and target SDK version 31, increase min Sdk to 21 (#1864)

The upgraded compile SDK requires an upgrade of gradle, which introduces a
build error with api lvl <21:
   > Error while processing [...]/app/src/main/res/drawable/ic_close_24dp.xml :
     Invalid color value ?attr/colorControlNormal
Explanation: https://stackoverflow.com/a/49501629

Also minor NDK update

app/build.gradle

@@ -26,8 +26,8 @@ dependencies {
 
 android {
     // Changes to these values need to be reflected in `../docker/Dockerfile`
-    compileSdkVersion 30
+    compileSdkVersion 31
-    buildToolsVersion '30.0.0'
+    buildToolsVersion '31.0.0'
     ndkVersion = "${ndkVersionShared}"
 
     buildTypes.debug.applicationIdSuffix ".debug"
@@ -40,8 +40,8 @@ android {
     }
     defaultConfig {
         applicationId "com.nutomic.syncthingandroid"
-        minSdkVersion 16
+        minSdkVersion 21
-        targetSdkVersion 30
+        targetSdkVersion 31
         versionCode 4327
         versionName "1.22.2-rc.3"
         testApplicationId 'com.nutomic.syncthingandroid.test'

app/src/main/java/com/nutomic/syncthingandroid/service/RestApi.java

@@ -57,6 +57,15 @@ public class RestApi {
 
     private static final String TAG = "RestApi";
 
+    private static final SimpleDateFormat dateFormat;
+    static {
+        if (android.os.Build.VERSION.SDK_INT < 24) {
+            dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
+        } else {
+            dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssXXX");
+        }
+    }
+
     /**
      * Compares folders by labels, uses the folder ID as fallback if the label is empty
      */
@@ -276,7 +285,7 @@ public class RestApi {
             remoteIgnoredDevice.deviceID = deviceId;
             remoteIgnoredDevice.address = deviceAddress;
             remoteIgnoredDevice.name = deviceName;
-            remoteIgnoredDevice.time = dateString(new Date());
+            remoteIgnoredDevice.time = dateFormat.format(new Date());
             mConfig.remoteIgnoredDevices.add(remoteIgnoredDevice);
             sendConfig();
             Log.d(TAG, "Ignored device [" + deviceId + "]");
@@ -310,7 +319,7 @@ public class RestApi {
                     IgnoredFolder ignoredFolder = new IgnoredFolder();
                     ignoredFolder.id = folderId;
                     ignoredFolder.label = folderLabel;
-                    ignoredFolder.time = dateString(new Date());
+                    ignoredFolder.time = dateFormat.format(new Date());
                     device.ignoredFolders.add(ignoredFolder);
                     if (BuildConfig.DEBUG) {
                         Log.v(TAG, "device.ignoredFolders = " + new Gson().toJson(device.ignoredFolders));
@@ -718,8 +727,4 @@ public class RestApi {
         }
     }
 
-    private String dateString(Date date) {
-        return new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssXXX").format(date);
-    }
-
 }

build.gradle

@@ -4,14 +4,14 @@ buildscript {
     ext {
         // Cannot be called "ndkVersion" as that leads to naming collision
         // Changes to this value must be reflected in `./docker/Dockerfile`
-        ndkVersionShared = '23.0.7599858'
+        ndkVersionShared = '23.2.8568313'
     }
     repositories {
         google()
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:4.0.1'
+        classpath 'com.android.tools.build:gradle:7.3.1'
         classpath 'com.github.ben-manes:gradle-versions-plugin:0.36.0'
 
         // NOTE: Do not place your application dependencies here; they belong

docker/Dockerfile

@@ -2,9 +2,9 @@ FROM openjdk:11
 
 ENV GO_VERSION 1.19.3
 
-ARG ANDROID_SDK_VERSION=7583922
+# Can be found scrolling down on this page:
-ARG ANDROID_SDK_FILENAME=commandlinetools-linux-${ANDROID_SDK_VERSION}_latest.zip
+# https://developer.android.com/studio/index.html#command-tools
-
+ARG ANDROID_SDK_FILENAME=commandlinetools-linux-9123335_latest.zip
 WORKDIR /opt
 
 # Install Go
@@ -26,11 +26,11 @@ ARG SDKMANAGER="${ANDROID_HOME}/cmdline-tools/bin/sdkmanager --sdk_root=${ANDROI
 # Accept the SDK license, as we can't install packages otherwise
 RUN yes | $SDKMANAGER --licenses > /dev/null
 
-# NDK version (r22 fails to build)
+# NDK version
-ENV NDK_VERSION 23.0.7599858
+ENV NDK_VERSION 23.2.8568313
 
 # Install other android packages, including NDK
-RUN $SDKMANAGER tools platform-tools "build-tools;29.0.3" "platforms;android-29" "extras;android;m2repository" "ndk;${NDK_VERSION}"
+RUN $SDKMANAGER tools platform-tools "build-tools;31.0.0" "platforms;android-31" "extras;android;m2repository" "ndk;${NDK_VERSION}"
 
 # Accept licenses of newly installed packages
 RUN yes | $SDKMANAGER --licenses

gradle/wrapper/gradle-wrapper.properties

@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-6.9-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.4-bin.zip

syncthing/build-syncthing.py

@@ -25,7 +25,6 @@ BUILD_TARGETS = [
         'goarch': 'arm64',
         'jni_dir': 'arm64-v8a',
         'cc': 'aarch64-linux-android21-clang',
-        'min_sdk': 21,
     },
     {
         'arch': 'x86',
@@ -38,7 +37,6 @@ BUILD_TARGETS = [
         'goarch': 'amd64',
         'jni_dir': 'x86_64',
         'cc': 'x86_64-linux-android21-clang',
-        'min_sdk': 21,
     }
 ]
 
@@ -88,7 +86,6 @@ subprocess.check_call([
 ])
 
 for target in BUILD_TARGETS:
-    target_min_sdk = str(target.get('min_sdk', min_sdk))
 
     print('Building syncthing for', target['arch'])