E / WindowManager：活动已泄露最初添加到此处的窗口

Question

我收到错误

以下是我的代码，

public class SendMail extends AsyncTask<Void,Void,Void> {

private Context context;
private Session session;
private String email;
private String subject;
private String message;
private ProgressDialog progressDialog;

public SendMail(Context context,String email, String subject,String message){

    this.context = context;
    this.email = email;
    this.subject = subject;
    this.message = message;
}

@Override
protected void onPreExecute() {

    super.onPreExecute();
    progressDialog = ProgressDialog.show(context,"Sending Email","Please Wait...",false,false);
}

@Override
protected void onPostExecute(Void aVoid) {

    super.onPostExecute(aVoid);
    progressDialog.dismiss();
    Toast.makeText(context,"Email Sent", Toast.LENGTH_LONG).show();
}

@Override
protected Void doInBackground(Void... voids) {

    Properties props = new Properties();

    props.put("mail.smtp.host", "smtp.gmail.com");
    props.put("mail.smtp.socketFactory.port","465");
    props.put("mail.smtp.socketFactory.class","javax.net.ssl.SSLSocketFactory");
    props.put("mail.smtp.auth","true");
    props.put("mail.smtp.port","465");

    session =Session.getDefaultInstance(props, new javax.mail.Authenticator(){
        protected PasswordAuthentication getPasswordAuthentication(){
            return new
                    PasswordAuthentication(Config.EMAIL, Config.PASSWORD);
        }
    });
    try {

        MimeMessage mm = new MimeMessage(session);
        mm.setFrom(new InternetAddress(Config.EMAIL));
        mm.addRecipient(Message.RecipientType.TO, new InternetAddress(email));
        mm.setSubject(subject);
        mm.setText(message);
        Transport.send(mm);

    }catch (MessagingException e){
        e.printStackTrace();
    }
    return null;
}
 }

我知道我得到一个错误，因为ProgressDialog正在运行而我的Activity被销毁。我应该放一个progressDialog.dismiss（）。所以我把它但是仍然，我收到了这个错误。

我不知道如何解决这个问题。希望有人帮助我。