fix final field initialized in the constructor set twice for issue al…

…ibaba#1873

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

@@ -37,7 +37,10 @@ public void accept(T object, Object value) {
  throw new JSONException("set " + fieldName + " error", e);
  }
 
- if (collection == Collections.EMPTY_LIST || collection == Collections.EMPTY_SET || collection == null) {
+ if (collection == Collections.EMPTY_LIST
+ || collection == Collections.EMPTY_SET
+ || collection == null
+ || collection.equals(value)) {
  return;
  }
 

core/src/test/java/com/alibaba/fastjson2/issues_1800/Issue1873.java

@@ -0,0 +1,29 @@
+package com.alibaba.fastjson2.issues_1800;
+
+import com.alibaba.fastjson2.JSONObject;
+import com.alibaba.fastjson2.TypeReference;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class Issue1873 {
+ @Test
+ public void test() {
+ String json = "[{\"array\":[\"test1\",\"test2\",\"test3\"]}]";
+ List<ListTest> values = JSONObject.parseObject(json, TypeReference.collectionType(List.class, ListTest.class));
+ assertEquals(json, JSONObject.toJSONString(values));
+ json = "{\"array\":[\"test1\",\"test2\",\"test3\"]}";
+ ListTest listTest = JSONObject.parseObject(json, ListTest.class);
+ assertEquals(json, JSONObject.toJSONString(listTest));
+ }
+
+ static class ListTest {
+ public final List<String> array;
+
+ public ListTest(List<String> array) {
+ this.array = array;
+ }
+ }
+}