bug fix for Date Field input empty string, fix issue #550

core/src/main/java/com/alibaba/fastjson2/reader/FieldReaderImplDate.java

@@ -230,6 +230,8 @@ public void readFieldValue(JSONReader jsonReader, T object) {
                     }
                     fieldValue = new java.util.Date(millis);
                 }
+            } else if (jsonReader.nextIfEmptyString()) {
+                fieldValue = null;
             } else {
                 long millis = jsonReader.readMillisFromString();
                 fieldValue = new java.util.Date(millis);

core/src/test/java/com/alibaba/fastjson2/issues/Issue550.java

@@ -0,0 +1,32 @@
+package com.alibaba.fastjson2.issues;
+
+import com.alibaba.fastjson2.JSON;
+import org.junit.jupiter.api.Test;
+
+import java.util.Date;
+
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+public class Issue550 {
+    @Test
+    public void test() {
+        Bean bean = JSON.parseObject("{\"date\":\"\"}", Bean.class);
+        assertNull(bean.date);
+        assertNull(JSON.parseObject("{\"date\":\"\"}").to(Bean.class).date);
+    }
+
+    public static class Bean {
+        public Date date;
+    }
+
+    @Test
+    public void test1() {
+        Bean1 bean = JSON.parseObject("{\"date\":\"\"}", Bean1.class);
+        assertNull(bean.date);
+        assertNull(JSON.parseObject("{\"date\":\"\"}").to(Bean1.class).date);
+    }
+
+    private static class Bean1 {
+        public Date date;
+    }
+}

fastjson1-compatible/src/test/java/com/alibaba/fastjson/v2issues/Issue550.java

@@ -0,0 +1,21 @@
+package com.alibaba.fastjson.v2issues;
+
+import com.alibaba.fastjson.JSON;
+import org.junit.jupiter.api.Test;
+
+import java.util.Date;
+
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+public class Issue550 {
+    @Test
+    public void test() {
+        Bean bean = JSON.parseObject("{\"date\":\"\"}", Bean.class);
+        assertNull(bean.date);
+        assertNull(JSON.parseObject("{\"date\":\"\"}").toJavaObject(Bean.class).date);
+    }
+
+    public static class Bean {
+        public Date date;
+    }
+}