Java Jackson JsonMappingException：无法反序列化实例
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Hymanson JsonMappingException: Can not deserialize instance
提问by Azhar92
I'm trying to convert my json data to a POJO object using Hymanson. Here is the MainActivity and my POJO class code. I'm basically getting a JsonMappingException error. I have also attached the whole log.
我正在尝试使用 Hymanson 将我的 json 数据转换为 POJO 对象。这是 MainActivity 和我的 POJO 类代码。我基本上收到了 JsonMappingException 错误。我还附上了整个日志。
MainActivity.java :
主活动.java :
ObjectMapper mapper = new ObjectMapper();
mapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
try {
List<Entries> results = mapper.readValue(new URL("http://collegewires.com/android/Hymansoncw.json"), new TypeReference<List<Entries>>(){});
for(int i=0;i<results.size();++i){
System.out.println(results.get(i).getName());
out = out + " ## " + results.get(i).getName();
txt.setText("1111");
}
} catch (JsonParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (JsonMappingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Entries.java (this is the POJO)
Entries.java（这是POJO）
package com.collegewires.Hymanson;
public class Entries {
public Entries(){
}
private String id, name, email, address, gender;
private Phone phone;
public Phone getPhone() {
return phone;
}
public void setPhone(Phone phone) {
this.phone = phone;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
@Override
public String toString() {
return "Entries:{id: " + id + ", name: " + name +
", email: " + email + ", address: " + address + ", gender: " + gender + ", phone: " + phone + "}";
}
public class Phone {
public Phone(){
}
public String mobile, home, office;
public String getMobile() {
return mobile;
}
public void setMobile(String mobile) {
this.mobile = mobile;
}
public String getHome() {
return home;
}
public void setHome(String home) {
this.home = home;
}
public String getOffice() {
return office;
}
public void setOffice(String office) {
this.office = office;
}
@Override
public String toString() {
return "Phone:{mobile: " + mobile + ", home: " + home +
", office: " + office + "}";
}
}
}
Now, I'm getting the following error in my log. Because of this, I'm unable to proceed with my work. Here is the log :
现在，我的日志中出现以下错误。因此，我无法继续我的工作。这是日志：
07-12 12:06:13.206: W/System.err(30593):
com.fasterxml.Hymanson.databind.JsonMappingException: Can not deserialize instance of java.util.ArrayList out of START_OBJECT token
07-12 12:06:13.206: W/System.err(30593): at [Source: http://collegewires.com/android/Hymansoncw.json; line: 1, column: 1]
07-12 12:06:13.211: W/System.err(30593): at com.fasterxml.Hymanson.databind.DeserializationContext.mappingException(DeserializationContext.java:575)
07-12 12:06:13.211: W/System.err(30593): at com.fasterxml.Hymanson.databind.DeserializationContext.mappingException(DeserializationContext.java:569)
07-12 12:06:13.211: W/System.err(30593): at com.fasterxml.Hymanson.databind.deser.std.CollectionDeserializer.handleNonArray(CollectionDeserializer.java:259)
07-12 12:06:13.211: W/System.err(30593): at com.fasterxml.Hymanson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:217)
07-12 12:06:13.211: W/System.err(30593): at com.fasterxml.Hymanson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:207)
07-12 12:06:13.211: W/System.err(30593): at com.fasterxml.Hymanson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:23)
07-12 12:06:13.211: W/System.err(30593): at com.fasterxml.Hymanson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2888)
07-12 12:06:13.211: W/System.err(30593): at com.fasterxml.Hymanson.databind.ObjectMapper.readValue(ObjectMapper.java:2018)
07-12 12:06:13.211: W/System.err(30593): at com.collegewires.Hymanson.MainActivity.onCreate(MainActivity.java:81)
07-12 12:06:13.211: W/System.err(30593): at android.app.Activity.performCreate(Activity.java:5250)
07-12 12:06:13.211: W/System.err(30593): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1097)
07-12 12:06:13.211: W/System.err(30593): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)
07-12 12:06:13.211: W/System.err(30593): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2297)
07-12 12:06:13.211: W/System.err(30593): at android.app.ActivityThread.access0(ActivityThread.java:152)
07-12 12:06:13.211: W/System.err(30593): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1282)
07-12 12:06:13.211: W/System.err(30593): at android.os.Handler.dispatchMessage(Handler.java:99)
07-12 12:06:13.211: W/System.err(30593): at android.os.Looper.loop(Looper.java:137)
07-12 12:06:13.211: W/System.err(30593): at android.app.ActivityThread.main(ActivityThread.java:5328)
07-12 12:06:13.211: W/System.err(30593): at java.lang.reflect.Method.invokeNative(Native Method)
07-12 12:06:13.211: W/System.err(30593): at java.lang.reflect.Method.invoke(Method.java:511)
07-12 12:06:13.211: W/System.err(30593): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
07-12 12:06:13.211: W/System.err(30593): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
07-12 12:06:13.211: W/System.err(30593): at dalvik.system.NativeStart.main(Native Method)
07-12 12:06:13.251: D/libEGL(30593): loaded /vendor/lib/egl/libEGL_POWERVR_SGX544_115.so
07-12 12:06:13.261: D/libEGL(30593): loaded /vendor/lib/egl/libGLESv1_CM_POWERVR_SGX544_115.so
07-12 12:06:13.266: D/libEGL(30593): loaded /vendor/lib/egl/libGLESv2_POWERVR_SGX544_115.so
07-12 12:06:13.271: I/(30593): !@IMGSRV: DATE: 2013.04.23(11:19:33) | BUILDER: LSI3D | REVISION: e9cd1377d8225457ae40
07-12 12:06:13.346: D/OpenGLRenderer(30593): Enabling debug mode 0
07-12 12:06:31.521: W/IInputConnectionWrapper(30593): setComposingText on inactive InputConnection
采纳答案by VenomVendor
Remove the Constructor in Entries& Phone
GetEntries results = mapper.readValue(new URL("http://collegewires.com/android/Hymansoncw.json"), GetEntries.class);Entries seems to be a parameter in your JSON.
删除条目和电话中的构造函数
GetEntries results = mapper.readValue(new URL("http://collegewires.com/android/Hymansoncw.json"), GetEntries.class);条目似乎是您的 JSON 中的一个参数。
GetEntries.java
获取条目.java
package com.collegewires.Hymanson;
import java.util.List;
public class GetEntries{
private List<Entries> entries;
public List<Entries> getEntries(){
return this.entries;
}
public void setEntries(List<Entries> entries){
this.entries = entries;
}
}
Entries.java
条目.java
package com.collegewires.Hymanson;
import java.util.List;
public class Entries{
private String address;
private String email;
private String gender;
private String id;
private String name;
private Phone phone;
public String getAddress(){
return this.address;
}
public void setAddress(String address){
this.address = address;
}
public String getEmail(){
return this.email;
}
public void setEmail(String email){
this.email = email;
}
public String getGender(){
return this.gender;
}
public void setGender(String gender){
this.gender = gender;
}
public String getId(){
return this.id;
}
public void setId(String id){
this.id = id;
}
public String getName(){
return this.name;
}
public void setName(String name){
this.name = name;
}
public Phone getPhone(){
return this.phone;
}
public void setPhone(Phone phone){
this.phone = phone;
}
}
Phone.java
电话.java
package com.collegewires.Hymanson;
import java.util.List;
public class Phone{
private String home;
private String mobile;
private String office;
public String getHome(){
return this.home;
}
public void setHome(String home){
this.home = home;
}
public String getMobile(){
return this.mobile;
}
public void setMobile(String mobile){
this.mobile = mobile;
}
public String getOffice(){
return this.office;
}
public void setOffice(String office){
this.office = office;
}
}
回答by drew moore
Can not deserialize instance of java.util.ArrayList out of START_OBJECT token
Can not deserialize instance of java.util.ArrayList out of START_OBJECT token
The key words here are ArrayListand START_OBJECT token. You cannot deserialize a single object into an array of objects. Try to make sense of doing that and you'll understand why.
这里的关键词是ArrayList和START_OBJECT token。您不能将单个对象反序列化为对象数组。试着理解这样做的意义，你就会明白为什么。
You can only deserialize an arrayof JSON objects into an array or collection of POJO's. Note that, whereas a JSON object is delimited by { }braces, an array is delimited by [ ]brackets, with some number of objects inside of it.
您只能将JSON 对象数组反序列化为 POJO 数组或集合。请注意，JSON 对象由{ }大括号分隔，而数组由[ ]括号分隔，其中包含一定数量的对象。
回答by Hank Lapidez
The structor of the json implies that you read it back in an object like this:
json 的构造函数意味着您在这样的对象中读回它：
class Response{
private List<Entries> entries = ....
public setEntries(List<Entrie> e)
public getEntries()....
}
and load like this
并像这样加载
Response results = mapper.readValue(new URL("http://collegewires.com/android/Hymansoncw.json"), Response.class);
