diff --git a/core/jni/android/graphics/GraphicsJNI.h b/core/jni/android/graphics/GraphicsJNI.h
index 5baa8f8740c2c..f6a9bc7c62d7a 100644
--- a/core/jni/android/graphics/GraphicsJNI.h
+++ b/core/jni/android/graphics/GraphicsJNI.h
@@ -127,7 +127,7 @@ public:
  */
 class JavaPixelAllocator : public SkBRDAllocator {
 public:
-    JavaPixelAllocator(JNIEnv* env);
+    explicit JavaPixelAllocator(JNIEnv* env);
     ~JavaPixelAllocator();
 
     virtual bool allocPixelRef(SkBitmap* bitmap, SkColorTable* ctable) override;
@@ -215,7 +215,7 @@ private:
 
 class AshmemPixelAllocator : public SkBitmap::Allocator {
 public:
-    AshmemPixelAllocator(JNIEnv* env);
+    explicit AshmemPixelAllocator(JNIEnv* env);
     ~AshmemPixelAllocator();
     virtual bool allocPixelRef(SkBitmap* bitmap, SkColorTable* ctable);
     android::Bitmap* getStorageObjAndReset() {
diff --git a/core/jni/android/graphics/Utils.h b/core/jni/android/graphics/Utils.h
index d1a74a0adf6cf..fffec5b87b814 100644
--- a/core/jni/android/graphics/Utils.h
+++ b/core/jni/android/graphics/Utils.h
@@ -28,7 +28,7 @@ namespace android {
 
 class AssetStreamAdaptor : public SkStreamRewindable {
 public:
-    AssetStreamAdaptor(Asset*);
+    explicit AssetStreamAdaptor(Asset*);
 
     virtual bool rewind();
     virtual size_t read(void* buffer, size_t size);
@@ -53,7 +53,7 @@ SkMemoryStream* CopyAssetToStream(Asset*);
  */
 class AutoFDSeek {
 public:
-    AutoFDSeek(int fd) : fFD(fd) {
+    explicit AutoFDSeek(int fd) : fFD(fd) {
         fCurr = ::lseek(fd, 0, SEEK_CUR);
     }
     ~AutoFDSeek() {
diff --git a/core/jni/android/graphics/YuvToJpegEncoder.h b/core/jni/android/graphics/YuvToJpegEncoder.h
index 1ea844ae3eb69..7e7b935df2761 100644
--- a/core/jni/android/graphics/YuvToJpegEncoder.h
+++ b/core/jni/android/graphics/YuvToJpegEncoder.h
@@ -18,7 +18,7 @@ public:
      */
     static YuvToJpegEncoder* create(int pixelFormat, int* strides);
 
-    YuvToJpegEncoder(int* strides);
+    explicit YuvToJpegEncoder(int* strides);
 
     /** Encode YUV data to jpeg,  which is output to a stream.
      *
@@ -47,7 +47,7 @@ protected:
 
 class Yuv420SpToJpegEncoder : public YuvToJpegEncoder {
 public:
-    Yuv420SpToJpegEncoder(int* strides);
+    explicit Yuv420SpToJpegEncoder(int* strides);
     virtual ~Yuv420SpToJpegEncoder() {}
 
 private:
@@ -61,7 +61,7 @@ private:
 
 class Yuv422IToJpegEncoder : public YuvToJpegEncoder {
 public:
-    Yuv422IToJpegEncoder(int* strides);
+    explicit Yuv422IToJpegEncoder(int* strides);
     virtual ~Yuv422IToJpegEncoder() {}
 
 private: