JAXB解组XML文件ObservableList

Question

我正在尝试解组我编组的XML文件，但是当我打印它时它返回"os.rozgonov.notebook.model.Problem@333c8d07“。

我看了这里，但它不工作Null Pointer Exception in JAXB RI ClassFactory

类问题：

import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;


public class Problem {
private StringProperty problems;


public Problem() {          
}

public Problem(String problems) {
    this.problems = new SimpleStringProperty(problems);
}

public String getproblems() {
    return problems.get();
}
public void setproblems(String problems) {
    this.problems.set(problems);
}
public StringProperty problemsProperty() {
    return problems;
}
@Override 
 public String toString(){return getproblems();}

}

包装器：

import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;

import javafx.collections.ObservableList;

@XmlRootElement(name = "probl")
public class ProblemListWrapper {

private ObservableList<Problem> problem;

@XmlJavaTypeAdapter(ListProblemAdapter.class)
public  ObservableList<Problem> getProblems() {
    return problem;
}

public void setProblems(ObservableList<Problem> problems) {
    this.problem = problems;
}

}

ListAdapter：

import javax.xml.bind.annotation.adapters.XmlAdapter;

import javafx.collections.FXCollections;
import javafx.collections.ObservableList;

public class ListProblemAdapter extends XmlAdapter<ListProblem, ObservableList<Problem>> {

  @Override
  public ObservableList<Problem> unmarshal(ListProblem v) throws Exception {
    ObservableList<Problem> problemData = FXCollections.observableArrayList(v.problem);
    return problemData;
  }

  @Override
  public ListProblem marshal(ObservableList<Problem> v) throws Exception {
      ListProblem problems = new ListProblem();
    v.stream().forEach((item) -> {
      problems.problem.add(item);
    });
    return problems;
  }
}

列表：

import java.util.ArrayList;
import java.util.List;

import javax.xml.bind.annotation.XmlElement;

public class ListProblem {

@XmlElement(name = "problem")
  List<Problem> problem = new ArrayList<>();

  public List<Problem> getproblems() {
    return problem;

  }   
}

和Main：

public void loadProblemDataFromFile(File file) {
    try {
        JAXBContext context = JAXBContext
                .newInstance(ProblemListWrapper.class);

        Unmarshaller um = context.createUnmarshaller();


        ProblemListWrapper wrap = (ProblemListWrapper)um.unmarshal(file);                  

        problemData.clear();
        problemData.addAll(wrap.getProblems());

        System.out.println(problemData.get(0).toString());

        setProblemFilePath(file);


    } catch (Exception e) { 
        Alert alert = new Alert(AlertType.ERROR);
        alert.setTitle("Error");
        alert.setHeaderText("Could not load data");
        alert.setContentText("Could not load data from file:\n" + file.getPath());

        alert.showAndWait();
    }
}
  public void saveProblemDataToFile(File file) {
    try {           
        JAXBContext context = JAXBContext
                .newInstance(ProblemListWrapper.class);
        Marshaller m = context.createMarshaller();
        m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);


        System.out.println(problemData.get(0).toString());


        ProblemListWrapper wrapper = new ProblemListWrapper();
        wrapper.setProblems(problemData);

        m.marshal(wrapper, file);


        setProblemFilePath(file);
    } catch (Exception e) { // catches ANY exception
        Alert alert = new Alert(AlertType.ERROR);
        alert.setTitle("Error");
        alert.setHeaderText("Could not save data");
        alert.setContentText("Could not save data to file:\n" + file.getPath());

        alert.showAndWait();
    }
}

Answer 1

Problem.class中的默认构造函数中存在问题

public Problem() {  
    **this(null);**

这就是全部