String json="A valid json";

Job job = new Gson().fromJson(json, Job.class);

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

以上的异常是因为类如下

public class Job {

private int id;

public int getId() {

    return id;

}

public void setId(int id) {

    this.id = id;

}

传递的json如下

{"id":""}

来自：http://*.com/questions/27886127/exception-in-thread-main-com-google-gson-jsonsyntaxexception-java-lang-number