加载方法的自定义异常

Question

我创建了一个自定义异常，以便当我浏览文件并关闭浏览器时，我会捕获错误并告诉用户“请选择一个文件”：

public class CancelException extends Exception {

    public CancelException() {
    }

    public CancelException(String message) {
        super(message);
    }

}

现在我试图在加载方法中输入它，但我看不到我可以在哪里输入它，因为已经有多个由 netbeans 自动生成的异常：

public static Person loadcons() throws IOException
{
    Person loadcons = null;
    JFileChooser chooser = new JFileChooser();
    int chooserOption = chooser.showSaveDialog(null);
    chooserOption = JFileChooser.APPROVE_OPTION;

    try {
        File file = new File (chooser.getSelectedFile().getAbsolutePath());
        ObjectInputStream input = new ObjectInputStream(new FileInputStream(file));
        loadcons = (Person) input.readObject();
        input.close();
        return loadcons;
    } catch (IOException ex) {
        System.out.println(ex.getMessage());
    } catch (ClassNotFoundException ex) {
        System.out.println(ex.getMessage());
    }
    return null;

}

private String toString(String PersonID) {
    throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
}

如果我是这门语言的初学者，我将不胜感激。

我尝试在加载方法中创建异常：

  public static Person loadcons() throws IOException, CancelException {
    Person loadcons = null;
    try {
        JFileChooser chooser = new JFileChooser();
        int chooserOption = chooser.showSaveDialog(null);
       if (chooserOption == JFileChooser.APPROVE_OPTION)
       {

        File file = new File(chooser.getSelectedFile().getAbsolutePath());
        ObjectInputStream input = new ObjectInputStream(new FileInputStream(file));

        loadcons = (Person) input.readObject();
        input.close();
        return loadcons;
       }
       else{
           throw new CancelException("ERROR MESSAGE");
       }
    } catch (IOException ex) {
        System.out.println(ex.getMessage());
    } catch (ClassNotFoundException ex) {
        System.out.println(ex.getMessage());
    }
    return null;

}

private String toString(String PersonID) {
    throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
}

但是没有抛出异常

Answer 1

我想在下面建议使用您的自定义异常--

import *.CancelException;

public static Person loadcons() throws IOException,CancelException 
  ..
  ..
try {
    ..
    ..
    } catch (IOException ex) {
        System.out.println(ex.getMessage());
    } catch (ClassNotFoundException ex) {
    System.out.println(ex.getMessage());
    }catch (Exception ex) {
        throw new CancelException("Please select a file");
   }
    return null;