Enabling lint

There are types of linting errors that seem worthy of being fixed.
I have adopted some cookie cutter solution to fix two types of errors:
1) Remove usage of asserts that are unsupported in ART
See: https://android.googlesource.com/platform/tools/base/+/master/lint/libs/lint-checks/src/main/java/com/android/tools/lint/checks/AssertDetector.java

2) Replace HashMaps with SparseArrays
Which seemed appropriate based on a rudimentary glance.
See: https://stackoverflow.com/questions/25560629/sparsearray-vs-hashmap

If you feel like these replacements are appropriate, I can replace them at a bunch of more places and enable linting

Author: ashwinraghav

firebase-firestore/firebase-firestore.gradle

@@ -59,9 +59,7 @@ android {
         multiDexEnabled true
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
     }
-    lintOptions {
-        abortOnError false
-    }
+
     sourceSets {
         main {
             proto {

firebase-firestore/src/main/java/com/google/cloud/datastore/core/number/IndexNumberEncoder.java

@@ -14,6 +14,8 @@
 
 package com.google.cloud.datastore.core.number;
 
+import com.google.firebase.firestore.BuildConfig;
+
 /**
  * Encodes numbers (longs and doubles) as bytes whose order matches the numeric order.
  *
@@ -296,7 +298,8 @@ private static int encodeNumber(
 
       // Store exponents [4, 19] biased as [0, 15]
       exponent -= EXP1_END;
-      assert exponent <= 0xF;
+      if(BuildConfig.DEBUG && !(exponent <= 0xF))
+        throw new RuntimeException();
 
       // Store exponent as low order 4 bits, no continuation bit
       lastByte |= exponent;
@@ -314,7 +317,8 @@ private static int encodeNumber(
 
       // Store exponents [20, 147] biased as [0, 127]
       exponent -= EXP2_END;
-      assert exponent <= 0x7F;
+      if(BuildConfig.DEBUG && !(exponent <= 0x7F))
+        throw new RuntimeException();
 
       // Pack the top 3 bits of the 7 bit exponent as the low order bits
       lastByte |= exponent >>> 4;
@@ -342,7 +346,8 @@ private static int encodeNumber(
 
       // Store exponents [148, 1171] biased as [0, 1023]
       exponent -= EXP3_END;
-      assert exponent <= 0x3FF;
+      if(BuildConfig.DEBUG && !(exponent <= 0x3FF))
+        throw new RuntimeException();
 
       // Pack the top 2 bits of the exponent as the low order bits
       lastByte |= exponent >>> 8;

firebase-firestore/src/main/java/com/google/cloud/datastore/core/number/NumberIndexEncoder.java

@@ -16,6 +16,7 @@
 
 import static com.google.cloud.datastore.core.number.NumberParts.SIGNIFICAND_BITS;
 
+import com.google.firebase.firestore.BuildConfig;
 import java.util.Arrays;
 
 /**
@@ -194,7 +195,8 @@ public static byte[] encode(NumberParts parts) {
 
       // Store exponents [4, 19] biased as [0, 15]
       exponent -= EXP1_END;
-      assert exponent <= 0xF;
+      if(BuildConfig.DEBUG && !(exponent <= 0xF))
+        throw new RuntimeException();
 
       // Store exponent as low order 4 bits, no continuation bit
       lastByte |= exponent;
@@ -212,7 +214,8 @@ public static byte[] encode(NumberParts parts) {
 
       // Store exponents [20, 147] biased as [0, 127]
       exponent -= EXP2_END;
-      assert exponent <= 0x7F;
+      if(BuildConfig.DEBUG && !(exponent <= 0x7F))
+        throw new RuntimeException();
 
       // Pack the top 3 bits of the 7 bit exponent as the low order bits
       lastByte |= exponent >>> 4;
@@ -240,7 +243,8 @@ public static byte[] encode(NumberParts parts) {
 
       // Store exponents [148, 1171] biased as [0, 1023]
       exponent -= EXP3_END;
-      assert exponent <= 0x3FF;
+      if(BuildConfig.DEBUG && !(exponent <= 0x3FF))
+        throw new RuntimeException();
 
       // Pack the top 2 bits of the exponent as the low order bits
       lastByte |= exponent >>> 8;

firebase-firestore/src/main/java/com/google/firebase/firestore/remote/RemoteStore.java

@@ -17,6 +17,7 @@
 import static com.google.firebase.firestore.util.Assert.hardAssert;
 
 import android.support.annotation.Nullable;
+import android.util.SparseArray;
 import com.google.firebase.database.collection.ImmutableSortedSet;
 import com.google.firebase.firestore.core.OnlineState;
 import com.google.firebase.firestore.core.Transaction;
@@ -118,7 +119,7 @@ public interface RemoteStoreCallback {
    * removed with unlistens are removed eagerly without waiting for confirmation from the listen
    * stream.
    */
-  private final Map<Integer, QueryData> listenTargets;
+  private final SparseArray<QueryData> listenTargets;
 
   private final OnlineStateTracker onlineStateTracker;
 
@@ -152,7 +153,7 @@ public RemoteStore(
     this.localStore = localStore;
     this.datastore = datastore;
 
-    listenTargets = new HashMap<>();
+    listenTargets = new SparseArray<QueryData>();
     writePipeline = new ArrayDeque<>();
 
     onlineStateTracker =
@@ -292,8 +293,7 @@ public void handleCredentialChange() {
   /** Listens to the target identified by the given QueryData. */
   public void listen(QueryData queryData) {
     Integer targetId = queryData.getTargetId();
-    hardAssert(
-        !listenTargets.containsKey(targetId),
+    hardAssert(listenTargets.get(targetId) == null,
         "listen called with duplicate target ID: %d",
         targetId);
 
@@ -318,7 +318,8 @@ private void sendWatchRequest(QueryData queryData) {
    * be torn down after one minute of inactivity.
    */
   public void stopListening(int targetId) {
-    QueryData queryData = listenTargets.remove(targetId);
+    QueryData queryData = listenTargets.get(targetId);
+    listenTargets.remove(targetId);
     hardAssert(
         queryData != null, "stopListening called on target no currently watched: %d", targetId);
 
@@ -327,7 +328,7 @@ public void stopListening(int targetId) {
       sendUnwatchRequest(targetId);
     }
 
-    if (listenTargets.isEmpty()) {
+    if (listenTargets.size()==0) {
       if (watchStream.isOpen()) {
         watchStream.markIdle();
       } else if (this.canUseNetwork()) {
@@ -357,7 +358,7 @@ private boolean shouldStartWriteStream() {
    * active watch targets.
    */
   private boolean shouldStartWatchStream() {
-    return canUseNetwork() && !watchStream.isStarted() && !listenTargets.isEmpty();
+    return canUseNetwork() && !watchStream.isStarted() && listenTargets.size() != 0;
   }
 
   private void cleanUpWatchStreamState() {
@@ -378,9 +379,10 @@ private void startWatchStream() {
   }
 
   private void handleWatchStreamOpen() {
+    final int nsize = listenTargets.size();
     // Restore any existing watches.
-    for (QueryData queryData : listenTargets.values()) {
-      sendWatchRequest(queryData);
+    for(int i = 0; i < nsize; i++) {
+      sendWatchRequest(listenTargets.get(i));
     }
   }
 
@@ -515,7 +517,7 @@ private void processTargetError(WatchTargetChange targetChange) {
     hardAssert(targetChange.getCause() != null, "Processing target error without a cause");
     for (Integer targetId : targetChange.getTargetIds()) {
       // Ignore targets that have been removed already.
-      if (listenTargets.containsKey(targetId)) {
+      if (listenTargets.get(targetId) != null) {
         listenTargets.remove(targetId);
         watchChangeAggregator.removeTarget(targetId);
         remoteStoreCallback.handleRejectedListen(targetId, targetChange.getCause());