diff --git a/native/jni/src/binary_format.h b/native/jni/src/binary_format.h
index fdc13bf..2ee4077 100644
--- a/native/jni/src/binary_format.h
+++ b/native/jni/src/binary_format.h
@@ -572,8 +572,8 @@
     // 0 for the bigram frequency represents the middle of the 16th step from the top,
     // while a value of 15 represents the middle of the top step.
     // See makedict.BinaryDictInputOutput for details.
-    const float stepSize = ((float)MAX_FREQ - unigramFreq) / (1.5f + MAX_BIGRAM_FREQ);
-    return (int)(unigramFreq + (bigramFreq + 1) * stepSize);
+    const float stepSize = (static_cast<float>(MAX_FREQ) - unigramFreq) / (1.5f + MAX_BIGRAM_FREQ);
+    return static_cast<int>(unigramFreq + (bigramFreq + 1) * stepSize);
 }
 
 // This returns a probability in log space.
diff --git a/native/jni/src/char_utils.cpp b/native/jni/src/char_utils.cpp
index 88803cb..45d49b0 100644
--- a/native/jni/src/char_utils.cpp
+++ b/native/jni/src/char_utils.cpp
@@ -16,6 +16,8 @@
 
 #include <cstdlib>
 
+#include "char_utils.h"
+
 namespace latinime {
 
 struct LatinCapitalSmallPair {
diff --git a/native/jni/src/correction.cpp b/native/jni/src/correction.cpp
index 8bb27f5..ea4bdda 100644
--- a/native/jni/src/correction.cpp
+++ b/native/jni/src/correction.cpp
@@ -24,7 +24,6 @@
 #include "char_utils.h"
 #include "correction.h"
 #include "defines.h"
-#include "dictionary.h"
 #include "proximity_info_state.h"
 
 namespace latinime {
@@ -95,11 +94,11 @@
 //////////////////////
 // inline functions //
 //////////////////////
-static const char QUOTE = '\'';
+static const char SINGLE_QUOTE = '\'';
 
-inline bool Correction::isQuote(const unsigned short c) {
+inline bool Correction::isSingleQuote(const unsigned short c) {
     const unsigned short userTypedChar = mProximityInfoState.getPrimaryCharAt(mInputIndex);
-    return (c == QUOTE && userTypedChar != QUOTE);
+    return (c == SINGLE_QUOTE && userTypedChar != SINGLE_QUOTE);
 }
 
 ////////////////
@@ -326,7 +325,7 @@
     mDistances[mOutputIndex] = NOT_A_DISTANCE;
 
     // Skip checking this node
-    if (mNeedsToTraverseAllNodes || isQuote(c)) {
+    if (mNeedsToTraverseAllNodes || isSingleQuote(c)) {
         bool incremented = false;
         if (mLastCharExceeded && mInputIndex == mInputLength - 1) {
             // TODO: Do not check the proximity if EditDistance exceeds the threshold
@@ -344,7 +343,7 @@
                 mDistances[mOutputIndex] = mProximityInfoState.getNormalizedSquaredDistance(
                         mInputIndex, proximityIndex);
             }
-            if (!isQuote(c)) {
+            if (!isSingleQuote(c)) {
                 incrementInputIndex();
                 incremented = true;
             }
@@ -791,7 +790,7 @@
                 static const float MIN = 0.3f;
                 static const float R1 = NEUTRAL_SCORE_SQUARED_RADIUS;
                 static const float R2 = HALF_SCORE_SQUARED_RADIUS;
-                const float x = (float)squaredDistance
+                const float x = static_cast<float>(squaredDistance)
                         / ProximityInfoState::NORMALIZED_SQUARED_DISTANCE_SCALING_FACTOR;
                 const float factor = max((x < R1)
                     ? (A * (R1 - x) + B * x) / R1
@@ -1133,13 +1132,14 @@
     }
 
     const float maxScore = score >= S_INT_MAX ? S_INT_MAX : MAX_INITIAL_SCORE
-            * pow((float)TYPED_LETTER_MULTIPLIER,
-                    (float)min(beforeLength, afterLength - spaceCount)) * FULL_WORD_MULTIPLIER;
+            * pow(static_cast<float>(TYPED_LETTER_MULTIPLIER),
+                    static_cast<float>(min(beforeLength, afterLength - spaceCount)))
+            * FULL_WORD_MULTIPLIER;
 
     // add a weight based on edit distance.
     // distance <= max(afterLength, beforeLength) == afterLength,
     // so, 0 <= distance / afterLength <= 1
-    const float weight = 1.0 - (float) distance / afterLength;
+    const float weight = 1.0f - static_cast<float>(distance) / static_cast<float>(afterLength);
     return (score / maxScore) * weight;
 }
 } // namespace latinime
diff --git a/native/jni/src/correction.h b/native/jni/src/correction.h
index a7028ac..81623a4 100644
--- a/native/jni/src/correction.h
+++ b/native/jni/src/correction.h
@@ -197,7 +197,7 @@
     inline void incrementInputIndex();
     inline void incrementOutputIndex();
     inline void startToTraverseAllNodes();
-    inline bool isQuote(const unsigned short c);
+    inline bool isSingleQuote(const unsigned short c);
     inline CorrectionType processSkipChar(
             const int32_t c, const bool isTerminal, const bool inputIndexIncremented);
     inline CorrectionType processUnrelatedCorrectionType();
diff --git a/native/jni/src/defines.h b/native/jni/src/defines.h
index e172b04..2b30f3c 100644
--- a/native/jni/src/defines.h
+++ b/native/jni/src/defines.h
@@ -88,7 +88,7 @@
         AKLOGI("Error: You must call PROF_OPEN before PROF_CLOSE.");
     }
     AKLOGI("Total time is %6.3f ms.",
-            profile_buf[PROF_BUF_SIZE - 1] * 1000 / (float)CLOCKS_PER_SEC);
+            profile_buf[PROF_BUF_SIZE - 1] * 1000.0f / static_cast<float>(CLOCKS_PER_SEC));
     float all = 0;
     for (int i = 0; i < PROF_BUF_SIZE - 1; ++i) {
         all += profile_buf[i];
@@ -98,7 +98,8 @@
         if (profile_buf[i]) {
             AKLOGI("(%d): Used %4.2f%%, %8.4f ms. Called %d times.",
                     i, (profile_buf[i] * 100 / all),
-                    profile_buf[i] * 1000 / (float)CLOCKS_PER_SEC, profile_counter[i]);
+                    profile_buf[i] * 1000.0f / static_cast<float>(CLOCKS_PER_SEC),
+                    profile_counter[i]);
         }
     }
 }
diff --git a/native/jni/src/dictionary.cpp b/native/jni/src/dictionary.cpp
index b9f6534..6c72211 100644
--- a/native/jni/src/dictionary.cpp
+++ b/native/jni/src/dictionary.cpp
@@ -16,10 +16,14 @@
 
 #define LOG_TAG "LatinIME: dictionary.cpp"
 
+#include <stdint.h>
+
+#include "bigram_dictionary.h"
 #include "binary_format.h"
 #include "defines.h"
 #include "dictionary.h"
 #include "gesture_decoder_wrapper.h"
+#include "unigram_dictionary.h"
 
 namespace latinime {
 
@@ -52,6 +56,37 @@
     delete mGestureDecoder;
 }
 
+int Dictionary::getSuggestions(ProximityInfo *proximityInfo, int *xcoordinates, int *ycoordinates,
+        int *times, int *pointerIds, int *codes, int codesSize, int *prevWordChars,
+        int prevWordLength, int commitPoint, bool isGesture,
+        bool useFullEditDistance, unsigned short *outWords,
+        int *frequencies, int *spaceIndices, int *outputTypes) {
+    int result = 0;
+    if (isGesture) {
+        mGestureDecoder->setPrevWord(prevWordChars, prevWordLength);
+        result = mGestureDecoder->getSuggestions(proximityInfo, xcoordinates, ycoordinates,
+                times, pointerIds, codes, codesSize, commitPoint,
+                outWords, frequencies, spaceIndices, outputTypes);
+        return result;
+    } else {
+        std::map<int, int> bigramMap;
+        uint8_t bigramFilter[BIGRAM_FILTER_BYTE_SIZE];
+        mBigramDictionary->fillBigramAddressToFrequencyMapAndFilter(prevWordChars,
+                prevWordLength, &bigramMap, bigramFilter);
+        result = mUnigramDictionary->getSuggestions(proximityInfo, xcoordinates,
+                ycoordinates, codes, codesSize, &bigramMap, bigramFilter,
+                useFullEditDistance, outWords, frequencies, outputTypes);
+        return result;
+    }
+}
+
+int Dictionary::getBigrams(const int32_t *word, int length, int *codes, int codesSize,
+        unsigned short *outWords, int *frequencies, int *outputTypes) const {
+    if (length <= 0) return 0;
+    return mBigramDictionary->getBigrams(word, length, codes, codesSize, outWords, frequencies,
+            outputTypes);
+}
+
 int Dictionary::getFrequency(const int32_t *word, int length) const {
     return mUnigramDictionary->getFrequency(word, length);
 }
diff --git a/native/jni/src/dictionary.h b/native/jni/src/dictionary.h
index f625813..ab238c8 100644
--- a/native/jni/src/dictionary.h
+++ b/native/jni/src/dictionary.h
@@ -17,18 +17,17 @@
 #ifndef LATINIME_DICTIONARY_H
 #define LATINIME_DICTIONARY_H
 
-#include <map>
+#include <stdint.h>
 
-#include "bigram_dictionary.h"
-#include "char_utils.h"
 #include "defines.h"
-#include "incremental_decoder_interface.h"
-#include "proximity_info.h"
-#include "unigram_dictionary.h"
-#include "words_priority_queue_pool.h"
 
 namespace latinime {
 
+class BigramDictionary;
+class IncrementalDecoderInterface;
+class ProximityInfo;
+class UnigramDictionary;
+
 class Dictionary {
  public:
     // Taken from SuggestedWords.java
@@ -49,32 +48,10 @@
             int *times, int *pointerIds, int *codes, int codesSize, int *prevWordChars,
             int prevWordLength, int commitPoint, bool isGesture,
             bool useFullEditDistance, unsigned short *outWords,
-            int *frequencies, int *spaceIndices, int *outputTypes) {
-        int result = 0;
-        if (isGesture) {
-            mGestureDecoder->setPrevWord(prevWordChars, prevWordLength);
-            result = mGestureDecoder->getSuggestions(proximityInfo, xcoordinates, ycoordinates,
-                    times, pointerIds, codes, codesSize, commitPoint,
-                    outWords, frequencies, spaceIndices, outputTypes);
-            return result;
-        } else {
-            std::map<int, int> bigramMap;
-            uint8_t bigramFilter[BIGRAM_FILTER_BYTE_SIZE];
-            mBigramDictionary->fillBigramAddressToFrequencyMapAndFilter(prevWordChars,
-                    prevWordLength, &bigramMap, bigramFilter);
-            result = mUnigramDictionary->getSuggestions(proximityInfo, xcoordinates,
-                    ycoordinates, codes, codesSize, &bigramMap, bigramFilter,
-                    useFullEditDistance, outWords, frequencies, outputTypes);
-            return result;
-        }
-    }
+            int *frequencies, int *spaceIndices, int *outputTypes);
 
     int getBigrams(const int32_t *word, int length, int *codes, int codesSize,
-            unsigned short *outWords, int *frequencies, int *outputTypes) const {
-        if (length <= 0) return 0;
-        return mBigramDictionary->getBigrams(word, length, codes, codesSize, outWords, frequencies,
-                outputTypes);
-    }
+            unsigned short *outWords, int *frequencies, int *outputTypes) const;
 
     int getFrequency(const int32_t *word, int length) const;
     bool isValidBigram(const int32_t *word1, int length1, const int32_t *word2, int length2) const;
@@ -82,7 +59,7 @@
     int getDictSize() const { return mDictSize; }
     int getMmapFd() const { return mMmapFd; }
     int getDictBufAdjust() const { return mDictBufAdjust; }
-    ~Dictionary();
+    virtual ~Dictionary();
 
     // public static utility methods
     // static inline methods should be defined in the header file
diff --git a/native/jni/src/proximity_info.cpp b/native/jni/src/proximity_info.cpp
index 53ae1ea..cee408d 100644
--- a/native/jni/src/proximity_info.cpp
+++ b/native/jni/src/proximity_info.cpp
@@ -22,10 +22,9 @@
 #define LOG_TAG "LatinIME: proximity_info.cpp"
 
 #include "additional_proximity_chars.h"
+#include "char_utils.h"
 #include "defines.h"
-#include "dictionary.h"
 #include "proximity_info.h"
-#include "proximity_info_state.h"
 
 namespace latinime {
 
@@ -216,7 +215,7 @@
 void ProximityInfo::getCenters(int *centerXs, int *centerYs, int *codeToKeyIndex,
         int *keyToCodeIndex, int *keyCount, int *keyWidth) const {
     *keyCount = KEY_COUNT;
-    *keyWidth = sqrt((float)MOST_COMMON_KEY_WIDTH_SQUARE);
+    *keyWidth = sqrt(static_cast<float>(MOST_COMMON_KEY_WIDTH_SQUARE));
 
     for (int i = 0; i < KEY_COUNT; ++i) {
         const int code = mKeyCharCodes[i];
diff --git a/native/jni/src/proximity_info_state.cpp b/native/jni/src/proximity_info_state.cpp
index 04a2017..86c8a69 100644
--- a/native/jni/src/proximity_info_state.cpp
+++ b/native/jni/src/proximity_info_state.cpp
@@ -14,14 +14,12 @@
  * limitations under the License.
  */
 
-#include <cassert>
+#include <cstring> // for memset()
 #include <stdint.h>
 
 #define LOG_TAG "LatinIME: proximity_info_state.cpp"
 
-#include "additional_proximity_chars.h"
 #include "defines.h"
-#include "dictionary.h"
 #include "proximity_info.h"
 #include "proximity_info_state.h"
 
@@ -131,8 +129,8 @@
         const int keyIndex, const int inputIndex) const {
     const float sweetSpotCenterX = mProximityInfo->getSweetSpotCenterXAt(keyIndex);
     const float sweetSpotCenterY = mProximityInfo->getSweetSpotCenterYAt(keyIndex);
-    const float inputX = (float)mInputXCoordinates[inputIndex];
-    const float inputY = (float)mInputYCoordinates[inputIndex];
+    const float inputX = static_cast<float>(mInputXCoordinates[inputIndex]);
+    const float inputY = static_cast<float>(mInputYCoordinates[inputIndex]);
     return square(inputX - sweetSpotCenterX) + square(inputY - sweetSpotCenterY);
 }
 } // namespace latinime
diff --git a/native/jni/src/proximity_info_state.h b/native/jni/src/proximity_info_state.h
index 456e3ec..76d4551 100644
--- a/native/jni/src/proximity_info_state.h
+++ b/native/jni/src/proximity_info_state.h
@@ -17,11 +17,9 @@
 #ifndef LATINIME_PROXIMITY_INFO_STATE_H
 #define LATINIME_PROXIMITY_INFO_STATE_H
 
-#include <cassert>
 #include <stdint.h>
 #include <string>
 
-#include "additional_proximity_chars.h"
 #include "char_utils.h"
 #include "defines.h"
 
diff --git a/native/jni/src/unigram_dictionary.cpp b/native/jni/src/unigram_dictionary.cpp
index efcf512..b6b0210 100644
--- a/native/jni/src/unigram_dictionary.cpp
+++ b/native/jni/src/unigram_dictionary.cpp
@@ -19,13 +19,15 @@
 
 #define LOG_TAG "LatinIME: unigram_dictionary.cpp"
 
+#include "binary_format.h"
 #include "char_utils.h"
 #include "defines.h"
 #include "dictionary.h"
-#include "unigram_dictionary.h"
-
-#include "binary_format.h"
+#include "proximity_info.h"
 #include "terminal_attributes.h"
+#include "unigram_dictionary.h"
+#include "words_priority_queue.h"
+#include "words_priority_queue_pool.h"
 
 namespace latinime {
 
diff --git a/native/jni/src/words_priority_queue.h b/native/jni/src/words_priority_queue.h
index b24cf84..c0dedb5 100644
--- a/native/jni/src/words_priority_queue.h
+++ b/native/jni/src/words_priority_queue.h
@@ -18,7 +18,6 @@
 #define LATINIME_WORDS_PRIORITY_QUEUE_H
 
 #include <cstring> // for memcpy()
-#include <iostream>
 #include <queue>
 
 #include "correction.h"