gson.fromJson return null values

Question

This is My JSON String : "{'userName' : 'Bachooo'}"

Converting JSON String to LoginVO logic is:

Gson gson = new GsonBuilder().excludeFieldsWithoutExposeAnnotation().create();
LoginVO loginFrom  = gson.fromJson(jsonInString, LoginVO.class);
System.out.println("userName " + loginFrom.getUserName()); // output null

My LoginVO.class is:

public class LoginVO {

 private String userName;
 private String password;

 public String getUserName()
 {
    return userName;
 }
 public void setUserName(String userName)
 {
    this.userName = userName;
 }
 public String getPassword()
 {
    return password;
 }
 public void setPassword(String password)
 {
    this.password = password;
 }

}

Note I am using jdk 1.8.0_92

Output of loginForm.getUserName() is NULL instead of "Bachooo" any idea about this issue?

Solution

Since you are setting excludeFieldsWithoutExposeAnnotation() configuration on the GsonBuilder you must put @Expose annotation on those fields you want to serialize/deserialize.

So in order for excludeFieldsWithoutExposeAnnotation() to serialize/deserialize your fields you must add that annotation:

@Expose
private String userName;
@Expose
private String password;

Or, you could remove excludeFieldsWithoutExposeAnnotation() from the GsonBuilder.

Comments

[OneCricketeer]

And what happens if you only use Gson gson = new Gson()?

[PAncho]

if i only use Gson gson = new Gson() Infinity loop at recursive calling com.google.gson.internal.$Gson$Types.resolve($Gson$Types.jav‌​a:375)

[Braj]

what excludeFieldsWithoutExposeAnnotation says? "only expose fields that are annotated and ignore the rest "

[Siguza]

Possible duplicate of How should I escape strings in JSON?

[Siguza]

^ i.e. single quotes are not valid JSON.

[PAncho]

Thanks man its work 100% all I need @Expose To my variable i need to initialized.

[Vikas Madhusudana]

Or the other option is to just say new GsonBuilder().create() if you dont have access to edit the class