Now classes.dex is too big for running on Android 2.3 devices, let's minimize the code

after compilation

android-app/build.gradle

@@ -39,6 +39,10 @@ android {
             proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard.cfg'
             zipAlignEnabled true
         }
+        debug {
+            minifyEnabled true
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-debug.cfg'
+        }
     }
     lintOptions {
         abortOnError false

android-app/proguard-debug.cfg

@@ -0,0 +1,130 @@
+-target 1.6
+-dontobfuscate
+-dontusemixedcaseclassnames
+-dontskipnonpubliclibraryclasses
+-dontpreverify
+-repackageclasses ''
+-allowaccessmodification
+-optimizations !code/simplification/arithmetic,!field/*,!class/merging/*,!code/allocation/variable
+-keepattributes *Annotation*
+
+-keep public class * extends android.app.Activity
+-keep public class * extends android.app.Application
+-keep public class * extends android.app.Service
+-keep public class * extends android.content.BroadcastReceiver
+-keep public class * extends android.content.ContentProvider
+
+-keep public class * extends android.view.View {
+    public <init>(android.content.Context);
+    public <init>(android.content.Context, android.util.AttributeSet);
+    public <init>(android.content.Context, android.util.AttributeSet, int);
+    public void set*(...);
+}
+
+-keepclasseswithmembers class * {
+    public <init>(android.content.Context, android.util.AttributeSet);
+}
+
+-keepclasseswithmembers class * {
+    public <init>(android.content.Context, android.util.AttributeSet, int);
+}
+
+-keepclassmembers class * extends android.content.Context {
+   public void *(android.view.View);
+   public void *(android.view.MenuItem);
+}
+
+-keepclassmembers class * implements android.os.Parcelable {
+    static android.os.Parcelable$Creator CREATOR;
+}
+
+-keepclassmembers class **.R$* {
+    public static <fields>;
+}
+
+-keepclassmembers enum * {
+    public static **[] values();
+    public static ** valueOf(java.lang.String);
+}
+
+-keep @org.simpleframework.xml.Root public class * {
+	*;
+}
+
+-dontwarn javax.xml.stream.**
+-dontwarn com.bea.xml.stream.**
+-dontwarn sun.misc.Unsafe
+-dontwarn android.annotation.TargetApi
+-dontwarn org.solovyev.common.math.visualisation.**
+-dontwarn org.solovyev.common.math.graph.**
+-dontwarn org.solovyev.common.math.algorithms.**
+-dontwarn org.solovyev.common.drawing.**
+-dontwarn org.joda.**
+-dontwarn jscl.mathml.**
+-dontwarn com.google.common.collect.MinMaxPriorityQueue
+-dontwarn com.google.ads.**
+-dontwarn com.sun.org.apache.xerces.internal.impl.dv.util.Base64
+-dontwarn com.actionbarsherlock.BuildConfig
+-dontwarn com.google.android.gms.**
+-dontwarn com.melnykov.fab.**
+
+-keep class org.simpleframework.xml.** { *; }
+-keep class * implements org.solovyev.android.calculator.model.MathPersistenceEntity
+-keep class * implements org.solovyev.android.calculator.MathEntityPersistenceContainer
+
+#
+#*********************************************************************
+#
+#                          SHERLOCK
+#
+#*********************************************************************
+#
+
+-keep class android.support.v4.app.** { *; }
+-keep interface android.support.v4.app.** { *; }
+-keep class com.actionbarsherlock.** { *; }
+-keep interface com.actionbarsherlock.** { *; }
+
+
+#
+#*********************************************************************
+#
+#                          ACRA
+#
+#*********************************************************************
+#
+
+# we need line numbers in our stack traces otherwise they are pretty useless
+-renamesourcefileattribute SourceFile
+-keepattributes SourceFile,LineNumberTable
+
+# ACRA needs "annotations" so add this...
+-keepattributes *Annotation*
+
+# keep this class so that logging will show 'ACRA' and not a obfuscated name like 'a'.
+# Note: if you are removing log messages elsewhere in this file then this isn't necessary
+-keep class org.acra.ACRA {
+    	*;
+}
+
+-keep class org.acra.ReportField {
+    	*;
+}
+
+
+# keep this around for some enums that ACRA needs
+-keep class org.acra.ReportingInteractionMode {
+   *;
+}
+
+# keep this otherwise it is removed by ProGuard
+-keep public class org.acra.ErrorReporter
+{
+public void addCustomData(java.lang.String,java.lang.String);
+}
+
+# keep this otherwise it is removed by ProGuard
+-keep public class org.acra.ErrorReporter
+{
+public org.acra.ErrorReporter$ReportsSenderWorker handleSilentException(java.lang.Throwable);
+}

android-app/proguard.cfg

@@ -65,6 +65,7 @@
 -dontwarn com.sun.org.apache.xerces.internal.impl.dv.util.Base64
 -dontwarn com.actionbarsherlock.BuildConfig
 -dontwarn com.google.android.gms.**
+-dontwarn com.melnykov.fab.**
 
 -keep class org.simpleframework.xml.** { *; }
 -keep class * implements org.solovyev.android.calculator.model.MathPersistenceEntity