I have a problem. I have the following JSON:
[
{
"Id":"8",
"MasterAgentId":"0",
"LastAgentStrategyId":"16116488969159",
"BotState":"Active",
"Owner":"Andre",
"ExtraNotifiers":"",
"Exchange":"lava",
"DateTime":"2021-01-27 22:12:02",
"AgentStatus":"Enabled",
"ProtectiveOrdersEnabled":"yes",
"Sim_Progress":"100",
"Sim_DateTime":"2021-01-27 09:18:00",
"Sim_Coin":"BTC",
"Sim_Price":"31626.580000",
"Sim_Profit":"1216.04",
"Sim_Profit_Perc":"60.80",
"Sim_StartDateTime":"2019-01-01 00:00:00",
"LastAgentStrategyRun":"2020-12-19 17:40:30.531000"
}
]
As you can see I have 4 DateTimes in the JSON: DateTime, Sim_DateTime, Sim_StartDateTime, LastAgentStrategyRun
Now I created a class for this that looks like this:
import java.time.LocalDateTime;
public class Agent {
private int Id;
private int MasterAgentId;
private long LastAgentStrategyId;
private AgentBotState BotState;
private String Owner;
private String ExtraNotifiers;
private AgentExchanges Exchange;
private LocalDateTime DateTime;
private AgentStatus AgentStatus;
private String ProtectiveOrdersEnabled;
private String Sim_Progress;
private String Sim_DateTime;
private String Sim_Coin;
private double Sim_Price;
private double Sim_Profit;
private double Sim_Profit_Perc;
private LocalDateTime Sim_StartDateTime;
private LocalDateTime LastAgentStrategyRun;
}
But when I deserialize the json using GSON:
Gson gson = new Gson();
Type listType = new TypeToken<ArrayList<Agent>>() {}.getType();
ArrayList<Agent> agentList = new Gson().fromJson(jsonResponse, listType);
I get the following error:
But the code crashes with the following error:
Exception in thread "main" com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 157 path $[0].DateTime
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:200)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:103)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:196)
at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:40)
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:81)
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:60)
at com.google.gson.Gson.fromJson(Gson.java:810)
at com.google.gson.Gson.fromJson(Gson.java:775)
at com.google.gson.Gson.fromJson(Gson.java:724)
at com.company.Main.main(Main.java:34)
Caused by: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 157 path $[0].DateTime
at com.google.gson.stream.JsonReader.beginObject(JsonReader.java:387)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:189)
... 9 more
Now when I remove all the datetimes from the json, it parses correctly with only a few weird warning:
WARNING: An illegal reflective access operation has occurred WARNING: Illegal reflective access by com.google.gson.internal.bind.ReflectiveTypeAdapterFactory (file:/C:/Users/Alexander/.m2/repository/com/google/code/gson/gson/2.3.1/gson-2.3.1.jar) to field java.time.LocalDateTime.date WARNING: Please consider reporting this to the maintainers of com.google.gson.internal.bind.ReflectiveTypeAdapterFactory WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations WARNING: All illegal access operations will be denied in a future release
How can I parse a datetime string to an object and how can I get rid of the warnings?
Afther using the following code:
Gson gson = new GsonBuilder().registerTypeAdapter(LocalDateTime.class, (JsonDeserializer<LocalDateTime>) (json, type, jsonDeserializationContext) -> {
Instant instant = Instant.ofEpochMilli(json.getAsJsonPrimitive().getAsLong());
return LocalDateTime.ofInstant(instant, ZoneId.systemDefault());
}).create();
Type listType = new TypeToken<ArrayList<Agent>>() {}.getType();
ArrayList<Agent> agentList = gson.fromJson(jsonResponse, listType);
I get this error now:
Exception in thread "main" java.lang.NumberFormatException: For input string: "2021-01-27 22:56:01"
at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:68)
at java.base/java.lang.Long.parseLong(Long.java:707)
at java.base/java.lang.Long.parseLong(Long.java:832)
at com.google.gson.JsonPrimitive.getAsLong(JsonPrimitive.java:238)
at com.company.Main.lambda$main$0(Main.java:35)
at com.google.gson.TreeTypeAdapter.read(TreeTypeAdapter.java:58)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:103)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:196)
at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:40)
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:81)
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:60)
at com.google.gson.Gson.fromJson(Gson.java:810)
at com.google.gson.Gson.fromJson(Gson.java:775)
at com.google.gson.Gson.fromJson(Gson.java:724)
at com.company.Main.main(Main.java:40)
You need to register LocalDateTime: e.g.replace Gson gson = new Gson(); see code below:
Updated answer to parse a LocalDateTime using a date formatter, instead of creating an Instant. Also your date formats are not consistent as some return seconds others milliseconds so I have provided two format alternatives.
Please see example code using a simplified Agent class
String jsonResponse = "[\n" +
" {\n" +
" \"DateTime\":\"2021-01-27 09:18:00\",\n" +
" \"Sim_StartDateTime\":\"2019-01-01 00:00:00\",\n" +
" \"LastAgentStrategyRun\":\"2020-12-19 17:40:30.531000\"\n" +
" }\n" +
']';
Gson gson = new GsonBuilder().registerTypeAdapter(LocalDateTime.class, (JsonDeserializer<LocalDateTime>) (json, type, jsonDeserializationContext) -> {
try{
return LocalDateTime.parse(json.getAsJsonPrimitive().getAsString(), DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));
} catch (DateTimeParseException e){
return LocalDateTime.parse(json.getAsJsonPrimitive().getAsString(), DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSSSSS"));
}
}).create();
Type listType = new TypeToken<ArrayList<Agent>>() {}.getType();
ArrayList<Agent> agentList = gson.fromJson(jsonResponse, listType);
System.out.println(agentList);
and the Agent class
public class Agent {
private LocalDateTime DateTime;
private LocalDateTime Sim_StartDateTime;
private LocalDateTime LastAgentStrategyRun;
public LocalDateTime getDateTime() {
return DateTime;
}
public void setDateTime(LocalDateTime dateTime) {
DateTime = dateTime;
}
public LocalDateTime getSim_StartDateTime() {
return Sim_StartDateTime;
}
public void setSim_StartDateTime(LocalDateTime sim_StartDateTime) {
Sim_StartDateTime = sim_StartDateTime;
}
public LocalDateTime getLastAgentStrategyRun() {
return LastAgentStrategyRun;
}
public void setLastAgentStrategyRun(LocalDateTime lastAgentStrategyRun) {
LastAgentStrategyRun = lastAgentStrategyRun;
}
@Override
public String toString() {
return "Agent{" +
"DateTime=" + DateTime +
", Sim_StartDateTime=" + Sim_StartDateTime +
", LastAgentStrategyRun=" + LastAgentStrategyRun +
'}';
}
}
and the output
[Agent{DateTime=2021-01-27T09:18, Sim_StartDateTime=2019-01-01T00:00, LastAgentStrategyRun=2020-12-19T17:40:30.531}]