[JVM] Add LabeledPoint read support

fix

jvm-packages/xgboost4j/src/test/java/ml/dmlc/xgboost4j/java/DMatrixTest.java

@@ -15,10 +15,12 @@
  */
 package ml.dmlc.xgboost4j.java;
 
+import java.awt.*;
 import java.util.Arrays;
 import java.util.Random;
 
 import junit.framework.TestCase;
+import ml.dmlc.xgboost4j.LabeledPoint;
 import ml.dmlc.xgboost4j.java.DMatrix;
 import ml.dmlc.xgboost4j.java.DataBatch;
 import ml.dmlc.xgboost4j.java.XGBoostError;
@@ -34,33 +36,19 @@ public class DMatrixTest {
   @Test
   public void testCreateFromDataIterator() throws XGBoostError {
     //create DMatrix from DataIterator
-    /**
-     * sparse matrix
-     * 1 0 2 3 0
-     * 4 0 2 3 5
-     * 3 1 2 5 0
-     */
-    DataBatch batch = new DataBatch();
-    batch.featureIndex = new int[]{0, 2, 3, 0, 2, 3, 4, 0, 1, 2, 3};
-    batch.featureValue = new float[]{1, 2, 3, 4, 2, 3, 5, 3, 1, 2, 5};
-    batch.rowOffset = new long[]{0, 3, 7, 11};
-    batch.label = new float[] {0.1f, 0.2f, 0.3f};
+
     java.util.ArrayList<Float> labelall = new java.util.ArrayList<Float>();
-    int nrep = 3;
-    java.util.List<DataBatch> blist = new java.util.LinkedList<DataBatch>();
+    int nrep = 3000;
+    java.util.List<LabeledPoint> blist = new java.util.LinkedList<LabeledPoint>();
     for (int i = 0; i < nrep; ++i) {
-      batch.label = new float[] {0.1f+i, 0.2f+i, 0.3f+i};
-      blist.add(batch.shallowCopy());
-      for (float f : batch.label) {
-        labelall.add(f);
-      }
+      LabeledPoint p = LabeledPoint.fromSparseVector(
+              0.1f + i, new int[]{0, 2, 3}, new float[]{3, 4, 5});
+      blist.add(p);
+      labelall.add(p.label);
     }
     DMatrix dmat = new DMatrix(blist.iterator(), null);
     // get label
     float[] labels = dmat.getLabel();
-    // get label
-    TestCase.assertTrue(batch.label.length * nrep == labels.length);
-
     for (int i = 0; i < labels.length; ++i) {
       TestCase.assertTrue(labelall.get(i) == labels[i]);
     }