Fix JNI for TableWithMeta to use schema_info instead of column_names (#…

…11566)

After #11364 `TableWithMeta` no longer returns the column names for a table since it is looking at the old `column_names` field instead of the newer `schema_info` field in the table metadata.  This updates the JNI to use the `schema_info` to get the column names and adds a test for this API which was missing before.

Authors:
  - Jason Lowe (https://github.com/jlowe)

Approvers:
  - Ryan Lee (https://github.com/rwlee)
  - Peixin (https://github.com/pxLi)

URL: #11566

java/src/main/java/ai/rapids/cudf/TableWithMeta.java

@@ -52,7 +52,7 @@ public String[] getColumnNames() {
   }
 
   @Override
-  public void close() throws Exception {
+  public void close() {
     if (handle != 0) {
       close(handle);
       handle = 0;

java/src/main/native/src/TableJni.cpp

@@ -1357,11 +1357,12 @@ JNIEXPORT jobjectArray JNICALL Java_ai_rapids_cudf_TableWithMeta_getColumnNames(
   try {
     cudf::jni::auto_set_device(env);
     auto ptr = reinterpret_cast<cudf::io::table_with_metadata *>(handle);
-    auto length = ptr->metadata.column_names.size();
+    auto length = ptr->metadata.schema_info.size();
     auto ret = static_cast<jobjectArray>(
         env->NewObjectArray(length, env->FindClass("java/lang/String"), nullptr));
     for (size_t i = 0; i < length; i++) {
-      env->SetObjectArrayElement(ret, i, env->NewStringUTF(ptr->metadata.column_names[i].c_str()));
+      env->SetObjectArrayElement(ret, i,
+                                 env->NewStringUTF(ptr->metadata.schema_info[i].name.c_str()));
     }
 
     return ret;

java/src/test/java/ai/rapids/cudf/TableTest.java

@@ -407,6 +407,30 @@ void testReadJSONBufferWithOffset() {
     }
   }
 
+  @Test
+  void testReadJSONTableWithMeta() {
+    JSONOptions opts = JSONOptions.builder()
+            .build();
+    byte[] data = ("{ \"A\": 1, \"B\": 2, \"C\": \"X\"}\n" +
+            "{ \"A\": 2, \"B\": 4, \"C\": \"Y\"}\n" +
+            "{ \"A\": 3, \"B\": 6, \"C\": \"Z\"}\n" +
+            "{ \"A\": 4, \"B\": 8, \"C\": \"W\"}\n").getBytes(StandardCharsets.UTF_8);
+    final int numBytes = data.length;
+    try (HostMemoryBuffer hostbuf = HostMemoryBuffer.allocate(numBytes)) {
+      hostbuf.setBytes(0, data, 0, numBytes);
+      try (Table expected = new Table.TestBuilder()
+              .column(1L, 2L, 3L, 4L)
+              .column(2L, 4L, 6L, 8L)
+              .column("X", "Y", "Z", "W")
+              .build();
+         TableWithMeta tablemeta = Table.readJSON(opts, hostbuf, 0, numBytes);
+         Table table = tablemeta.releaseTable()) {
+        assertArrayEquals(new String[] { "A", "B", "C" }, tablemeta.getColumnNames());
+        assertTablesAreEqual(expected, table);
+      }
+    }
+  }
+
   @Test
   void testReadCSVPrune() {
     Schema schema = Schema.builder()