在Java中创建新的JAXBContext实例时出现jaxb NullPointerException

Question

我有一个类可以将我的对象输出为XML，反之亦然。我的方法是使用JAXB和try/catch

当我运行程序时，我得到错误：

New Drawing object could not me instaned.Exception in thread "main" java.lang.NullPointerException
at se.miun.vife1700.dt062g.jpaint.FileHandler.saveToXML(FileHandler.java:21)
at se.miun.vife1700.dt062g.jpaint.Main.testDrawing(Main.java:53)
at se.miun.vife1700.dt062g.jpaint.Main.main(Main.java:21)

似乎我必须编写JAXBContext context=null；在试抓之前。但我如何以不同的方式做到这一点？当我抛出异常时，程序不会继续执行吗？我不熟悉JAVA，尤其是例外情况

感谢您的任何帮助

    import javax.xml.bind.*;
import java.io.File;
import java.util.Objects;


public class FileHandler {

    public static void saveToXML (Drawing drawing, String fileName) {

        JAXBContext context = null;
        try {
            context = JAXBContext.newInstance(Drawing.class);
        } catch (JAXBException e) {
            System.err.print("New Drawing object could not be instanced.");
        }
        Marshaller marshaller = null;
        try {
            marshaller = context.createMarshaller();
        } catch (JAXBException e) {
            System.err.print("Could not create a Marshaller");
        }

        try {
            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        } catch (PropertyException e) {
            System.err.print("A problem occurred when setting output format");
        }

        if(Objects.equals(".xml", fileName.substring(fileName.length() - 4))) {

            try {
                marshaller.marshal(drawing, new File(fileName));
            } catch (JAXBException e) {
                System.err.print("An error occurred when saving to file.");
            }
        }
        else {

            fileName += ".xml";
            try {
                marshaller.marshal(drawing, new File(fileName));
            } catch (JAXBException e) {
                System.err.print("An error occurred when saving to file.");
            }
        }

    }


    public static Drawing loadFromXML(String fileName){

        Drawing drawing = null;
        JAXBContext context = null;
        try {
            context = JAXBContext.newInstance(Drawing.class);
        } catch (JAXBException e) {
            System.err.print("New Drawing object could not be instanced.");
        }
        Unmarshaller unmarshaller = null;
        try {
            unmarshaller = context.createUnmarshaller();
        } catch (JAXBException e) {
            System.err.print("Could not create a Unmarshaller");
        }

        try {
            drawing = (Drawing) unmarshaller.unmarshal(
                    new File(fileName)
            );
        } catch (JAXBException e) {
            System.err.print("An error occurred when loading from file.");
        }

        return drawing;
    }


}

提前谢谢