Question

我正在尝试将json字符串反序列化为java对象，如下所示

String json="A valid json";
Job job = new Gson().fromJson(json, Job.class);

以上陈述引发了以下异常

Exception in thread "main" com.google.gson.JsonSyntaxException: java.lang.NumberFormatException: empty String
    at com.google.gson.internal.bind.TypeAdapters$7.read(TypeAdapters.java:241)
    at com.google.gson.internal.bind.TypeAdapters$7.read(TypeAdapters.java:231)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:93)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:172)
    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.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:93)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:172)
    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.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:93)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:172)
    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.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:93)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:172)
    at com.google.gson.Gson.fromJson(Gson.java:803)
    at com.google.gson.Gson.fromJson(Gson.java:768)
    at com.google.gson.Gson.fromJson(Gson.java:717)
    at com.google.gson.Gson.fromJson(Gson.java:689)
    at com.test.JobValidator.validate(JobValidator.java:10)
    at com.test.Test.main(Test.java:25)
Caused by: java.lang.NumberFormatException: empty String
    at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1011)
    at java.lang.Double.parseDouble(Double.java:540)
    at com.google.gson.stream.JsonReader.nextInt(JsonReader.java:1178)
    at com.google.gson.internal.bind.TypeAdapters$7.read(TypeAdapters.java:239)
    ... 24 more

这里Job是我为这个json结构定义的pojo。为什么我得到这个例外？如何解决？

Answer 1

您将收到此异常，因为json字符串中的值必须是数值。

ex：你的Pojo课程。

public class Job {

private int id;

public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}

你的json字符串：

{"id":""}

id必须是数值（例如：0）

此处提供更多信息：How to handle a NumberFormatException with Gson in deserialization a JSON response

线程“main”中的异常com.google.gson.JsonSyntaxException：java.lang.NumberFormatException：empty String

1 个答案: