java - 如何处理要传播给调用者的异常？

Question

我是一名正在转向 Java/Scala 的 Pythonista，我想知道如何处理您希望在发生异常时抛出异常的情况。以下面的玩具为例:

public class PersonSaver {
    private final File file;

    public PersonSaver(File file) {
        this.file = file;
    }

    public void save(List<Person> people) {
        try (ObjectOutputStream output = new ObjectOutputStream(new FileOutputStream(file))) {
            output.writeObject(people);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

在Python中，如果找不到文件，我希望它抛出一个错误，并让调用代码处理异常。惯例只是重新抛出相同的异常吗？

Answer 1

您可以让您的方法抛出这些异常:

public class PersonSaver {
    private final File file;

    public PersonSaver(File file) {
        this.file = file;
    }

    public void save(List<Person> people) throws FileNotFoundException {
        try (ObjectOutputStream output = new ObjectOutputStream(new FileOutputStream(file))) {
            output.writeObject(people);
        } catch (IOException e) {
            //handle the exception you want to handle
            e.printStackTrace();
        }
    }
}

只需确保使用 throws 语句声明您的方法，否则您的编译器可能不喜欢它;)

您也可以采用这种方式(我们称之为半异常处理):

public class PersonSaver {
    private final File file;

    public PersonSaver(File file) {
        this.file = file;
    }

    public void save(List<Person> people) throws FileNotFoundException, IOException {
        try (ObjectOutputStream output = new ObjectOutputStream(new FileOutputStream(file))) {
            output.writeObject(people);
        } catch (IOException e) {
            /*Some code to clear some data or to handle the 
              exception but still throw an exception higher*/
            throw e;
        }
    }
}