review feedback

Author: julienledem

java/vector/src/main/java/org/apache/arrow/vector/types/pojo/Field.java

@@ -19,7 +19,6 @@
 
 
 import static com.google.common.base.Preconditions.checkNotNull;
-import static java.lang.String.format;
 import static org.apache.arrow.vector.types.pojo.ArrowType.getTypeForField;
 
 import java.util.List;
@@ -145,15 +144,18 @@ public boolean equals(Object obj) {
             (Objects.equals(this.children, that.children) ||
                     (this.children == null && that.children.size() == 0) ||
                     (this.children.size() == 0 && that.children == null));
-
   }
 
   @Override
   public String toString() {
-    if (children.isEmpty()) {
-      return format("%s: %s", name, type);
-    } else {
-      return format("%s: %s{%s}", name, type, Joiner.on(",").join(children));
+    StringBuilder sb = new StringBuilder();
+    if (name != null) {
+      sb.append(name).append(": ");
+    }
+    sb.append(type);
+    if (!children.isEmpty()) {
+      sb.append("<").append(Joiner.on(", ").join(children)).append(">");
     }
+    return sb.toString();
   }
 }

java/vector/src/main/java/org/apache/arrow/vector/types/pojo/Schema.java

@@ -33,6 +33,7 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.ObjectReader;
 import com.fasterxml.jackson.databind.ObjectWriter;
+import com.google.common.base.Joiner;
 import com.google.common.collect.ImmutableList;
 import com.google.flatbuffers.FlatBufferBuilder;
 
@@ -132,6 +133,6 @@ public boolean equals(Object obj) {
 
   @Override
   public String toString() {
-    return "Schema" + fields;
+    return "Schema<" + Joiner.on(", ").join(fields) + ">";
   }
 }

java/vector/src/test/java/org/apache/arrow/vector/types/pojo/TestSchema.java

@@ -39,6 +39,24 @@ private static Field field(String name, ArrowType type, Field... children) {
     return field(name, true, type, children);
   }
 
+  @Test
+  public void testComplex() throws IOException {
+    Schema schema = new Schema(asList(
+        field("a", false, new ArrowType.Int(8, true)),
+        field("b", new ArrowType.Struct(),
+            field("c", new ArrowType.Int(16, true)),
+            field("d", new ArrowType.Utf8())),
+        field("e", new ArrowType.List(), field(null, new ArrowType.Date())),
+        field("f", new ArrowType.FloatingPoint(FloatingPointPrecision.SINGLE)),
+        field("g", new ArrowType.Timestamp(TimeUnit.MILLISECOND)),
+        field("h", new ArrowType.Interval(IntervalUnit.DAY_TIME))
+        ));
+    roundTrip(schema);
+    assertEquals(
+        "Schema<a: Int(8, true), b: Struct<c: Int(16, true), d: Utf8>, e: List<Date>, f: FloatingPoint(SINGLE), g: Timestamp(MILLISECOND), h: Interval(DAY_TIME)>",
+        schema.toString());
+  }
+
   @Test
   public void testAll() throws IOException {
     Schema schema = new Schema(asList(