bug fix for parse from single item array, for issue #3276

Author: wenshao

core/src/main/java/com/alibaba/fastjson2/JSONReader.java

@@ -4749,8 +4749,12 @@ public ObjectReader getObjectReaderAutoType(long typeHash, Class expectClass, lo
     protected final String readStringNotMatch() {
         switch (ch) {
             case '[':
-                return toString(
-                        readArray());
+                List array = readArray();
+                if (array.size() == 1) {
+                    Object item = array.get(0);
+                    return item == null ? null : item.toString();
+                }
+                return toString(array);
             case '{':
                 return toString(
                         readObject());

core/src/main/java/com/alibaba/fastjson2/JSONReaderUTF8.java

@@ -5004,39 +5004,7 @@ public String readString() {
             return str;
         }
 
-        switch (ch) {
-            case '[':
-                return toString(
-                        readArray());
-            case '{':
-                return toString(
-                        readObject());
-            case '-':
-            case '+':
-            case '0':
-            case '1':
-            case '2':
-            case '3':
-            case '4':
-            case '5':
-            case '6':
-            case '7':
-            case '8':
-            case '9':
-                readNumber0();
-                Number number = getNumber();
-                return number.toString();
-            case 't':
-            case 'f':
-                boolValue = readBoolValue();
-                return boolValue ? "true" : "false";
-            case 'n': {
-                readNull();
-                return null;
-            }
-            default:
-                throw new JSONException("TODO : " + ch);
-        }
+        return readStringNotMatch();
     }
 
     @Override

core/src/main/java/com/alibaba/fastjson2/util/TypeUtils.java

@@ -3051,7 +3051,16 @@ public static double toDoubleValue(Object value) {
             return 0;
         }
 
-        throw new JSONException("can not cast to decimal");
+        if (value instanceof Collection && ((Collection<?>) value).size() == 1) {
+            Object first = ((Collection<?>) value).iterator().next();
+            if (first instanceof Number) {
+                return ((Number) first).doubleValue();
+            } else if (first instanceof String) {
+                return Double.parseDouble((String) first);
+            }
+        }
+
+        throw new JSONException("can not cast to double");
     }
 
     public static Double toDouble(Object value) {
@@ -3071,7 +3080,7 @@ public static Double toDouble(Object value) {
             return Double.parseDouble(str);
         }
 
-        throw new JSONException("can not cast to decimal");
+        throw new JSONException("can not cast to double");
     }
 
     public static int compare(Object a, Object b) {

core/src/test/java/com/alibaba/fastjson2/issues_3200/Issue3276.java

@@ -0,0 +1,34 @@
+package com.alibaba.fastjson2.issues_3200;
+
+import com.alibaba.fastjson2.JSON;
+import lombok.Data;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class Issue3276 {
+    @Test
+    public void jsonSerializationTest3() {
+        String json = "{\n" +
+                "    \"c\":[\"1.1\"]\n" +
+                "}";
+
+        Bean bean = JSON.parseObject(json, Bean.class);
+        assertEquals(1.1D, bean.getC());
+    }
+
+    @Test
+    public void jsonSerializationTest2() {
+        String json = "{\n" +
+                "    \"b\":['1']\n" +
+                "}";
+        Bean bean = JSON.parseObject(json, Bean.class);
+        assertEquals('1', bean.getB());
+    }
+
+    @Data
+    public static class Bean {
+        private Character b;
+        private Double c;
+    }
+}

core/src/test/java/com/alibaba/fastjson2/read/ParserTest_string.java

@@ -163,24 +163,23 @@ void lexerTest(JSONReader lexer) {
         assertEquals(Fnv.hashCode64("v12"), lexer.readFieldNameHashCode());
         assertEquals(Fnv.hashCode64LCase("v12"), lexer.getNameHashCodeLCase());
         assertEquals("v12", lexer.getFieldName());
-        assertEquals("[1234]", lexer
+        assertEquals("1234", lexer
                 .readString());
 
         assertEquals(Fnv.hashCode64("v13"), lexer.readFieldNameHashCode());
         assertEquals(Fnv.hashCode64LCase("v13"), lexer.getNameHashCodeLCase());
         assertEquals("v13", lexer.getFieldName());
-        assertEquals("[12.34]", lexer.readString());
+        assertEquals("12.34", lexer.readString());
 
         assertEquals(Fnv.hashCode64("v14"), lexer.readFieldNameHashCode());
         assertEquals(Fnv.hashCode64LCase("v14"), lexer.getNameHashCodeLCase());
         assertEquals("v14", lexer.getFieldName());
-        assertEquals("[null]",
-                lexer.readString());
+        assertNull(lexer.readString());
 
         assertEquals(Fnv.hashCode64("v15"), lexer.readFieldNameHashCode());
         assertEquals(Fnv.hashCode64LCase("v15"), lexer.getNameHashCodeLCase());
         assertEquals("v15", lexer.getFieldName());
-        assertEquals("[\"123\"]",
+        assertEquals("123",
                 lexer.readString());
 
         assertEquals('}', lexer.current());