public class MainActivity extensions AppCompatActivity{
@ Override
protected void onCreate (Bundle savedInstanceState) {
ObjectMapper mapper = new ObjectMapper();
try{
JackSon response=mapper.readValue(
new URL ("http://express.heartrails.com/api/json?method=getAreas"),
JackSon.class);
String m=response.get("response").get(0).get("area").asText();
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextView textView= (TextView) findViewById (R.id.text_view);
textView.setText(String.valueOf(m));
} catch(IOExceptione){
e.printStackTrace();
}
}
}
In the above code, the response.get get has the error Cannot resolve method 'get(java.lang.String)'.
@Data
public class JackSon{
private area response;
@ Data
public class area {
private String [ ] area;
}
}
How can I display this code?
[
{
"a": "xxx",
"b" —yyy
},
{
"a": "xxxx",
"b" —yyyy
},
{
"a": "xx",
"b" —yy
}
]
How can I change it if I want to display JSON data like this instead of the above URL?
java android-studio json jackson
JavaBean class JackSon:
import com.fasterxml.jackson.announcement.JsonProperty;
import java.util.List;
public class JackSon{
@ JsonProperty ("response")
private response;
public void setResponse(Response response) {
this.response=response;
}
public Response getResponse(){
return response;
}
public static class Response {
@ JsonProperty ("area")
private List <String > area;
public void setArea(List<String>area){
This.area=area;
}
publicList<String>getArea(){
return area;
}
}
}
public class MainActivity extensions AppCompatActivity{
@ Override
protected void onCreate (Bundle savedInstanceState) {
ObjectMapper mapper = new ObjectMapper();
JackSon response=null;
try{
response=mapper.readValue(new URL("http://express.heartrails.com/api/json?method=getAreas"), JackSon.class);
final List<String>area=response.getResponse().getArea();
final Strings=area.toString();
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextView textView= (TextView) findViewById (R.id.text_view);
textView.setText(String.valueOf(m));
} catch(IOExceptione){
e.printStackTrace();
}
}
}
In the above code, the response.get get has the error Cannot resolve method 'get(java.lang.String)'.
I think @Data is Lombok annotation, so getter is generated automatically.Therefore, the code for retrieving area data is
response.getResponse().getArea();
is the case.
(It's not directly related to the question, but you don't need to define the Area class as a nonstatic internal class, and generally you shouldn't.)
How can I change it if I want to display JSON data like this instead of the above URL?
Conversion of JSON with the top level [] depends on whether you convert it to an array or to a list.
@Data
US>class MyData{
private String a;
private intb;
}
For classes defined as :
a) When converting to an array
MyData[]myDataArray=mapper.readValue(...,MyData[].class);
b) To convert to a list
List<MyData>myDataList=mapper.readValue(..., new TypeReference<List<MyData>>(){});
(However, even if you want to convert it to a list, it is faster to convert it to an array using the former method and then to a list instead of using TypeReference.See the reference link below.)
Note:
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