在下面的例子中，我必须解析一个json字符串，它是一个对象的序列化，该对象可能是CustomClass_1或CustomClass_2的示例，我事先并不知道它。问题如下：

• 我得到一个异常com.google.gson.jsonSyntaxException：java.lang.IllegalStateException:应为开始_OBJECT，但实际为BEGIN_ARRAY
• GSON从CustomClass_2示例中生成的json字符串只是字符串 [“item”]，就好像该对象只是超类 ArrayList 的一个示例一样

有什么建议可以实现我的愿望吗？

class CustomClass_1 {
  String type;

  CustomClass_1(){
    type = "CustomClass_1";
  }
}

class CustomClass_2 extends ArrayList<String> {
  String type;

  CustomClass_2(){
    super();
    type = "CustomClass_2";
    this.add("item");
  }
}

public class DeserializationTest {

  @Test
  public void testIncomingMessageParsing(){
    String serialized_object = receive();
    CustomClass_1 cc1 = null;
    CustomClass_2 cc2 = null;
    try{
      cc1 = (new Gson()).fromJson(serialized_object, CustomClass_1.class);
    } catch (Exception e){
      e.printStackTrace();
    }
    try{
      cc2 = (new Gson()).fromJson(serialized_object, CustomClass_2.class);
    } catch (Exception e){
      e.printStackTrace();
    }
    if (cc1 != null && cc1.type.equals("CustomClass_1")) {
      System.out.println("It's a CustomClass_1.");
    } else if (cc2 != null && cc2.type.equals("CustomClass_2")) {
      System.out.println("It's a CustomClass_2.");
    }
  }

  String receive(){
    CustomClass_1 cc1 = new CustomClass_1();
    CustomClass_2 cc2 = new CustomClass_2();
    String serialized_object = "";
    Gson gson = new Gson();
    boolean head = (new Random()).nextBoolean();
    if (head){
      serialized_object = gson.toJson(cc1);
    } else {
      serialized_object = gson.toJson(cc2);
    }
    return serialized_object;
  }
} // end of class