diff --git a/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/Booster.java b/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/Booster.java
index 672d538ea..92438121d 100644
--- a/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/Booster.java
+++ b/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/Booster.java
@@ -35,16 +35,6 @@ public class Booster implements Serializable, KryoSerializable {
   // handle to the booster.
   private long handle = 0;
 
-  //load native library
-  static {
-    try {
-      NativeLibLoader.initXGBoost();
-    } catch (IOException ex) {
-      logger.error("load native library failed.");
-      logger.error(ex);
-    }
-  }
-
   /**
    * Create a new Booster with empty stage.
    *
@@ -70,7 +60,7 @@ public class Booster implements Serializable, KryoSerializable {
       throw new NullPointerException("modelPath : null");
     }
     Booster ret = new Booster(new HashMap<String, Object>(), new DMatrix[0]);
-    JNIErrorHandle.checkCall(XGBoostJNI.XGBoosterLoadModel(ret.handle, modelPath));
+    XGBoostJNI.checkCall(XGBoostJNI.XGBoosterLoadModel(ret.handle, modelPath));
     return ret;
   }
 
@@ -93,7 +83,7 @@ public class Booster implements Serializable, KryoSerializable {
     }
     in.close();
     Booster ret = new Booster(new HashMap<String, Object>(), new DMatrix[0]);
-    JNIErrorHandle.checkCall(XGBoostJNI.XGBoosterLoadModelFromBuffer(ret.handle,os.toByteArray()));
+    XGBoostJNI.checkCall(XGBoostJNI.XGBoosterLoadModelFromBuffer(ret.handle,os.toByteArray()));
     return ret;
   }
 
@@ -105,7 +95,7 @@ public class Booster implements Serializable, KryoSerializable {
    * @throws XGBoostError native error
    */
   public final void setParam(String key, Object value) throws XGBoostError {
-    JNIErrorHandle.checkCall(XGBoostJNI.XGBoosterSetParam(handle, key, value.toString()));
+    XGBoostJNI.checkCall(XGBoostJNI.XGBoosterSetParam(handle, key, value.toString()));
   }
 
   /**
@@ -130,7 +120,7 @@ public class Booster implements Serializable, KryoSerializable {
    * @throws XGBoostError native error
    */
   public void update(DMatrix dtrain, int iter) throws XGBoostError {
-    JNIErrorHandle.checkCall(XGBoostJNI.XGBoosterUpdateOneIter(handle, iter, dtrain.getHandle()));
+    XGBoostJNI.checkCall(XGBoostJNI.XGBoosterUpdateOneIter(handle, iter, dtrain.getHandle()));
   }
 
   /**
@@ -159,7 +149,7 @@ public class Booster implements Serializable, KryoSerializable {
       throw new AssertionError(String.format("grad/hess length mismatch %s / %s", grad.length,
               hess.length));
     }
-    JNIErrorHandle.checkCall(XGBoostJNI.XGBoosterBoostOneIter(handle,
+    XGBoostJNI.checkCall(XGBoostJNI.XGBoosterBoostOneIter(handle,
             dtrain.getHandle(), grad, hess));
   }
 
@@ -175,7 +165,7 @@ public class Booster implements Serializable, KryoSerializable {
   public String evalSet(DMatrix[] evalMatrixs, String[] evalNames, int iter) throws XGBoostError {
     long[] handles = dmatrixsToHandles(evalMatrixs);
     String[] evalInfo = new String[1];
-    JNIErrorHandle.checkCall(XGBoostJNI.XGBoosterEvalOneIter(handle, iter, handles, evalNames,
+    XGBoostJNI.checkCall(XGBoostJNI.XGBoosterEvalOneIter(handle, iter, handles, evalNames,
             evalInfo));
     return evalInfo[0];
   }
@@ -243,7 +233,7 @@ public class Booster implements Serializable, KryoSerializable {
       optionMask = 2;
     }
     float[][] rawPredicts = new float[1][];
-    JNIErrorHandle.checkCall(XGBoostJNI.XGBoosterPredict(handle, data.getHandle(), optionMask,
+    XGBoostJNI.checkCall(XGBoostJNI.XGBoosterPredict(handle, data.getHandle(), optionMask,
             treeLimit, rawPredicts));
     int row = (int) data.rowNum();
     int col = rawPredicts[0].length / row;
@@ -309,7 +299,7 @@ public class Booster implements Serializable, KryoSerializable {
    * @param modelPath model path
    */
   public void saveModel(String modelPath) throws XGBoostError{
-    JNIErrorHandle.checkCall(XGBoostJNI.XGBoosterSaveModel(handle, modelPath));
+    XGBoostJNI.checkCall(XGBoostJNI.XGBoosterSaveModel(handle, modelPath));
   }
 
   /**
@@ -349,7 +339,7 @@ public class Booster implements Serializable, KryoSerializable {
       format = "text";
     }
     String[][] modelInfos = new String[1][];
-    JNIErrorHandle.checkCall(
+    XGBoostJNI.checkCall(
             XGBoostJNI.XGBoosterDumpModelEx(handle, featureMap, statsFlag, format, modelInfos));
     return modelInfos[0];
   }
@@ -397,7 +387,7 @@ public class Booster implements Serializable, KryoSerializable {
       statsFlag = 1;
     }
     String[][] modelInfos = new String[1][];
-    JNIErrorHandle.checkCall(XGBoostJNI.XGBoosterDumpModelEx(handle, "", statsFlag, "text",
+    XGBoostJNI.checkCall(XGBoostJNI.XGBoosterDumpModelEx(handle, "", statsFlag, "text",
             modelInfos));
     return modelInfos[0];
   }
@@ -409,7 +399,7 @@ public class Booster implements Serializable, KryoSerializable {
    */
   public byte[] toByteArray() throws XGBoostError {
     byte[][] bytes = new byte[1][];
-    JNIErrorHandle.checkCall(XGBoostJNI.XGBoosterGetModelRaw(this.handle, bytes));
+    XGBoostJNI.checkCall(XGBoostJNI.XGBoosterGetModelRaw(this.handle, bytes));
     return bytes[0];
   }
 
@@ -421,7 +411,7 @@ public class Booster implements Serializable, KryoSerializable {
    */
   int loadRabitCheckpoint() throws XGBoostError {
     int[] out = new int[1];
-    JNIErrorHandle.checkCall(XGBoostJNI.XGBoosterLoadRabitCheckpoint(this.handle, out));
+    XGBoostJNI.checkCall(XGBoostJNI.XGBoosterLoadRabitCheckpoint(this.handle, out));
     return out[0];
   }
 
@@ -431,7 +421,7 @@ public class Booster implements Serializable, KryoSerializable {
    * @throws XGBoostError
    */
   void saveRabitCheckpoint() throws XGBoostError {
-    JNIErrorHandle.checkCall(XGBoostJNI.XGBoosterSaveRabitCheckpoint(this.handle));
+    XGBoostJNI.checkCall(XGBoostJNI.XGBoosterSaveRabitCheckpoint(this.handle));
   }
 
   /**
@@ -445,7 +435,7 @@ public class Booster implements Serializable, KryoSerializable {
       handles = dmatrixsToHandles(cacheMats);
     }
     long[] out = new long[1];
-    JNIErrorHandle.checkCall(XGBoostJNI.XGBoosterCreate(handles, out));
+    XGBoostJNI.checkCall(XGBoostJNI.XGBoosterCreate(handles, out));
 
     handle = out[0];
   }
@@ -479,7 +469,7 @@ public class Booster implements Serializable, KryoSerializable {
     try {
       this.init(null);
       byte[] bytes = (byte[])in.readObject();
-      JNIErrorHandle.checkCall(XGBoostJNI.XGBoosterLoadModelFromBuffer(this.handle, bytes));
+      XGBoostJNI.checkCall(XGBoostJNI.XGBoosterLoadModelFromBuffer(this.handle, bytes));
     } catch (XGBoostError ex) {
       ex.printStackTrace();
       logger.error(ex.getMessage());
@@ -521,7 +511,7 @@ public class Booster implements Serializable, KryoSerializable {
       System.out.println("==== the size of the object: " + serObjSize);
       byte[] bytes = new byte[serObjSize];
       input.readBytes(bytes);
-      JNIErrorHandle.checkCall(XGBoostJNI.XGBoosterLoadModelFromBuffer(this.handle, bytes));
+      XGBoostJNI.checkCall(XGBoostJNI.XGBoosterLoadModelFromBuffer(this.handle, bytes));
     } catch (XGBoostError ex) {
       ex.printStackTrace();
       logger.error(ex.getMessage());
diff --git a/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/DMatrix.java b/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/DMatrix.java
index b2b55597c..e0fc1247c 100644
--- a/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/DMatrix.java
+++ b/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/DMatrix.java
@@ -15,12 +15,8 @@
  */
 package ml.dmlc.xgboost4j.java;
 
-import java.io.IOException;
 import java.util.Iterator;
 
-import org.apache.commons.logging.Log;
-import org.apache.commons.logging.LogFactory;
-
 import ml.dmlc.xgboost4j.LabeledPoint;
 
 /**
@@ -29,19 +25,8 @@ import ml.dmlc.xgboost4j.LabeledPoint;
  * @author hzx
  */
 public class DMatrix {
-  private static final Log logger = LogFactory.getLog(DMatrix.class);
   protected long handle = 0;
 
-  //load native library
-  static {
-    try {
-      NativeLibLoader.initXGBoost();
-    } catch (IOException ex) {
-      logger.error("load native library failed.");
-      logger.error(ex);
-    }
-  }
-
   /**
    * sparse matrix type (CSR or CSC)
    */
@@ -65,7 +50,7 @@ public class DMatrix {
     int batchSize = 32 << 10;
     Iterator<DataBatch> batchIter = new DataBatch.BatchIterator(iter, batchSize);
     long[] out = new long[1];
-    JNIErrorHandle.checkCall(XGBoostJNI.XGDMatrixCreateFromDataIter(batchIter, cacheInfo, out));
+    XGBoostJNI.checkCall(XGBoostJNI.XGDMatrixCreateFromDataIter(batchIter, cacheInfo, out));
     handle = out[0];
   }
 
@@ -80,7 +65,7 @@ public class DMatrix {
       throw new NullPointerException("dataPath: null");
     }
     long[] out = new long[1];
-    JNIErrorHandle.checkCall(XGBoostJNI.XGDMatrixCreateFromFile(dataPath, 1, out));
+    XGBoostJNI.checkCall(XGBoostJNI.XGDMatrixCreateFromFile(dataPath, 1, out));
     handle = out[0];
   }
 
@@ -96,9 +81,9 @@ public class DMatrix {
   public DMatrix(long[] headers, int[] indices, float[] data, SparseType st) throws XGBoostError {
     long[] out = new long[1];
     if (st == SparseType.CSR) {
-      JNIErrorHandle.checkCall(XGBoostJNI.XGDMatrixCreateFromCSREx(headers, indices, data, 0, out));
+      XGBoostJNI.checkCall(XGBoostJNI.XGDMatrixCreateFromCSREx(headers, indices, data, 0, out));
     } else if (st == SparseType.CSC) {
-      JNIErrorHandle.checkCall(XGBoostJNI.XGDMatrixCreateFromCSCEx(headers, indices, data, 0, out));
+      XGBoostJNI.checkCall(XGBoostJNI.XGDMatrixCreateFromCSCEx(headers, indices, data, 0, out));
     } else {
       throw new UnknownError("unknow sparsetype");
     }
@@ -119,10 +104,10 @@ public class DMatrix {
           throws XGBoostError {
     long[] out = new long[1];
     if (st == SparseType.CSR) {
-      JNIErrorHandle.checkCall(XGBoostJNI.XGDMatrixCreateFromCSREx(headers, indices, data,
+      XGBoostJNI.checkCall(XGBoostJNI.XGDMatrixCreateFromCSREx(headers, indices, data,
               shapeParam, out));
     } else if (st == SparseType.CSC) {
-      JNIErrorHandle.checkCall(XGBoostJNI.XGDMatrixCreateFromCSCEx(headers, indices, data,
+      XGBoostJNI.checkCall(XGBoostJNI.XGDMatrixCreateFromCSCEx(headers, indices, data,
               shapeParam, out));
     } else {
       throw new UnknownError("unknow sparsetype");
@@ -140,7 +125,7 @@ public class DMatrix {
    */
   public DMatrix(float[] data, int nrow, int ncol) throws XGBoostError {
     long[] out = new long[1];
-    JNIErrorHandle.checkCall(XGBoostJNI.XGDMatrixCreateFromMat(data, nrow, ncol, 0.0f, out));
+    XGBoostJNI.checkCall(XGBoostJNI.XGDMatrixCreateFromMat(data, nrow, ncol, 0.0f, out));
     handle = out[0];
   }
 
@@ -153,7 +138,7 @@ public class DMatrix {
    */
   public DMatrix(float[] data, int nrow, int ncol, float missing) throws XGBoostError {
     long[] out = new long[1];
-    JNIErrorHandle.checkCall(XGBoostJNI.XGDMatrixCreateFromMat(data, nrow, ncol, missing, out));
+    XGBoostJNI.checkCall(XGBoostJNI.XGDMatrixCreateFromMat(data, nrow, ncol, missing, out));
     handle = out[0];
   }
 
@@ -172,7 +157,7 @@ public class DMatrix {
    * @throws XGBoostError native error
    */
   public void setLabel(float[] labels) throws XGBoostError {
-    JNIErrorHandle.checkCall(XGBoostJNI.XGDMatrixSetFloatInfo(handle, "label", labels));
+    XGBoostJNI.checkCall(XGBoostJNI.XGDMatrixSetFloatInfo(handle, "label", labels));
   }
 
   /**
@@ -182,7 +167,7 @@ public class DMatrix {
    * @throws XGBoostError native error
    */
   public void setWeight(float[] weights) throws XGBoostError {
-    JNIErrorHandle.checkCall(XGBoostJNI.XGDMatrixSetFloatInfo(handle, "weight", weights));
+    XGBoostJNI.checkCall(XGBoostJNI.XGDMatrixSetFloatInfo(handle, "weight", weights));
   }
 
   /**
@@ -193,7 +178,7 @@ public class DMatrix {
    * @throws XGBoostError native error
    */
   public void setBaseMargin(float[] baseMargin) throws XGBoostError {
-    JNIErrorHandle.checkCall(XGBoostJNI.XGDMatrixSetFloatInfo(handle, "base_margin", baseMargin));
+    XGBoostJNI.checkCall(XGBoostJNI.XGDMatrixSetFloatInfo(handle, "base_margin", baseMargin));
   }
 
   /**
@@ -215,18 +200,18 @@ public class DMatrix {
    * @throws XGBoostError native error
    */
   public void setGroup(int[] group) throws XGBoostError {
-    JNIErrorHandle.checkCall(XGBoostJNI.XGDMatrixSetGroup(handle, group));
+    XGBoostJNI.checkCall(XGBoostJNI.XGDMatrixSetGroup(handle, group));
   }
 
   private float[] getFloatInfo(String field) throws XGBoostError {
     float[][] infos = new float[1][];
-    JNIErrorHandle.checkCall(XGBoostJNI.XGDMatrixGetFloatInfo(handle, field, infos));
+    XGBoostJNI.checkCall(XGBoostJNI.XGDMatrixGetFloatInfo(handle, field, infos));
     return infos[0];
   }
 
   private int[] getIntInfo(String field) throws XGBoostError {
     int[][] infos = new int[1][];
-    JNIErrorHandle.checkCall(XGBoostJNI.XGDMatrixGetUIntInfo(handle, field, infos));
+    XGBoostJNI.checkCall(XGBoostJNI.XGDMatrixGetUIntInfo(handle, field, infos));
     return infos[0];
   }
 
@@ -269,7 +254,7 @@ public class DMatrix {
    */
   public DMatrix slice(int[] rowIndex) throws XGBoostError {
     long[] out = new long[1];
-    JNIErrorHandle.checkCall(XGBoostJNI.XGDMatrixSliceDMatrix(handle, rowIndex, out));
+    XGBoostJNI.checkCall(XGBoostJNI.XGDMatrixSliceDMatrix(handle, rowIndex, out));
     long sHandle = out[0];
     DMatrix sMatrix = new DMatrix(sHandle);
     return sMatrix;
@@ -283,7 +268,7 @@ public class DMatrix {
    */
   public long rowNum() throws XGBoostError {
     long[] rowNum = new long[1];
-    JNIErrorHandle.checkCall(XGBoostJNI.XGDMatrixNumRow(handle, rowNum));
+    XGBoostJNI.checkCall(XGBoostJNI.XGDMatrixNumRow(handle, rowNum));
     return rowNum[0];
   }
 
diff --git a/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/JNIErrorHandle.java b/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/JNIErrorHandle.java
deleted file mode 100644
index c8888154b..000000000
--- a/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/JNIErrorHandle.java
+++ /dev/null
@@ -1,52 +0,0 @@
-/*
- Copyright (c) 2014 by Contributors
-
- Licensed under the Apache License, Version 2.0 (the "License");
- you may not use this file except in compliance with the License.
- You may obtain a copy of the License at
-
- http://www.apache.org/licenses/LICENSE-2.0
-
- Unless required by applicable law or agreed to in writing, software
- distributed under the License is distributed on an "AS IS" BASIS,
- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- See the License for the specific language governing permissions and
- limitations under the License.
- */
-package ml.dmlc.xgboost4j.java;
-
-import java.io.IOException;
-
-import org.apache.commons.logging.Log;
-import org.apache.commons.logging.LogFactory;
-
-/**
- * Error handle for Xgboost.
- */
-class JNIErrorHandle {
-
-  private static final Log logger = LogFactory.getLog(DMatrix.class);
-
-  //load native library
-  static {
-    try {
-      NativeLibLoader.initXGBoost();
-    } catch (IOException ex) {
-      logger.error("load native library failed.");
-      logger.error(ex);
-    }
-  }
-
-  /**
-   * Check the return value of C API.
-   *
-   * @param ret return valud of xgboostJNI C API call
-   * @throws XGBoostError native error
-   */
-  static void checkCall(int ret) throws XGBoostError {
-    if (ret != 0) {
-      throw new XGBoostError(XGBoostJNI.XGBGetLastError());
-    }
-  }
-
-}
diff --git a/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/NativeLibLoader.java b/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/NativeLibLoader.java
index 3fa05e0ed..1b5438cd5 100644
--- a/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/NativeLibLoader.java
+++ b/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/NativeLibLoader.java
@@ -21,7 +21,6 @@ import java.lang.reflect.Field;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
-
 /**
  * class to load native library
  *
@@ -35,7 +34,7 @@ class NativeLibLoader {
   private static final String nativeResourcePath = "/lib/";
   private static final String[] libNames = new String[]{"xgboost4j"};
 
-  public static synchronized void initXGBoost() throws IOException {
+  static synchronized void initXGBoost() throws IOException {
     if (!initialized) {
       for (String libName : libNames) {
         smartLoad(libName);
diff --git a/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/Rabit.java b/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/Rabit.java
index 6e996494b..710165d4c 100644
--- a/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/Rabit.java
+++ b/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/Rabit.java
@@ -1,30 +1,14 @@
 package ml.dmlc.xgboost4j.java;
 
-import java.io.IOException;
 import java.io.Serializable;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
-import java.util.Arrays;
 import java.util.Map;
 
-import org.apache.commons.logging.Log;
-import org.apache.commons.logging.LogFactory;
-
 /**
  * Rabit global class for synchronization.
  */
 public class Rabit {
-  private static final Log logger = LogFactory.getLog(DMatrix.class);
-  //load native library
-  static {
-    try {
-      NativeLibLoader.initXGBoost();
-    } catch (IOException ex) {
-      logger.error("load native library failed.");
-      logger.error(ex);
-    }
-  }
-
   public enum OpType implements Serializable {
     MAX(0), MIN(1), SUM(2), BITWISE_OR(3);
 
diff --git a/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/XGBoostJNI.java b/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/XGBoostJNI.java
index 4d0f31dd1..6922f26b0 100644
--- a/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/XGBoostJNI.java
+++ b/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/XGBoostJNI.java
@@ -15,9 +15,11 @@
  */
 package ml.dmlc.xgboost4j.java;
 
-
 import java.nio.ByteBuffer;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
 /**
  * xgboost JNI functions
  * change 2015-7-6: *use a long[] (length=1) as container of handle to get the output DMatrix or Booster
@@ -25,6 +27,28 @@ import java.nio.ByteBuffer;
  * @author hzx
  */
 class XGBoostJNI {
+  private static final Log logger = LogFactory.getLog(DMatrix.class);
+
+  static {
+    try {
+      NativeLibLoader.initXGBoost();
+    } catch (Exception ex) {
+      logger.error("Failed to load native library", ex);
+      throw new RuntimeException(ex);
+    }
+  }
+
+  /**
+   * Check the return code of the JNI call.
+   *
+   * @throws XGBoostError if the call failed.
+   */
+  static void checkCall(int ret) throws XGBoostError {
+    if (ret != 0) {
+      throw new XGBoostError(XGBGetLastError());
+    }
+  }
+
   public final static native String XGBGetLastError();
 
   public final static native int XGDMatrixCreateFromFile(String fname, int silent, long[] out);
@@ -104,4 +128,4 @@ class XGBoostJNI {
   // This JNI function does not support the callback function for data preparation yet.
   final static native int RabitAllreduce(ByteBuffer sendrecvbuf, int count,
                                                 int enum_dtype, int enum_op);
-}                                                                             
+}