如何在Java Mail API中使用搜索方法

Question

I am using the javamail api to make a Search option which Searches the Emails in the Gmail Folder on the Basis of a Keyword present in the Subject of the Messages Here is the Code that i am Using

public class EGMail7 {
public static void main(String args[])
{
    Scanner sc = new Scanner(System.in);
    final String m10 = "abc@gmail.com";   
    final String n10 = "12345";
    string host = "smtp.gmail.com"; 
    try
    {
    Properties pro1 = new Properties();   
    pro1.put("mail.smtp.host", "smtp.gmail.com");    
    pro1.put("mail.smtp.socketFactory.port", "465");
    pro1.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");  
    pro1.put("mail.smtp.auth", "true");   
    pro1.put("mail.smtp.port", "465");  
Session session = Session.getDefaultInstance(pro1, 
        new javax.mail.Authenticator()                  
{ 
    protected PasswordAuthentication getPasswordAuthentication()
{
        return new PasswordAuthentication(m10,n10);
        }
    }); 
    Store store = session.getStore("imaps");  
    store.connect(host, m10, n10); 
    Folder folderbox = store.getFolder("INBOX");
    folderbox.open(Folder.READ_ONLY);   
    SearchTerm search = new SearchTerm(){

        @Override
        public boolean match(Message message) {
            try
            {
                if(message.getSubject().contains([Keyword]))  
                {
                    return true;
                }
            }
            catch(Exception e)
            {
                System.err.println(e.getMessage());
            }
            return false;
        }

    };

    Message[] found = folderbox.search(search);

    int length = found.length;
    for(int i = 0;i<found.length;i++)
    {
        Message mess1 = found[i];
        System.out.println("->Message Number > "+i);
        System.out.println("->Message Subject >"+mess1.getSubject());
    }
    folderbox.close(true);
    store.close();
}
    catch(Exception e)
    {
        System.err.println(e.getMessage());
    }
   }
  }

I am using the Eclipse IDE and the problem i am facing is that whatever keyword I pass in the SearchTerm Method I always end up getting null Exception and an Message[] Found Array . I used Stack Trace to find out the Problem of this NullPointer Exception and it is at the line

Message[] found = folderbox.search(search);

I cannot Seem to understand what is the Problem Here ?

Regards, Thank you

PS - and if someone could also please post the corrected code it would be great Thanks

Also When i Am Just Adding the Keyword Directly in the SearchTerm it give an Error like

SearchTerm searchCon = new SearchTerm([Keyword]);

There are 2 Errors 1.Cannot Instantiate the SearchTerm 2.The Serializable class does not Declare a static final Serial Verison UID field of Type Long

So I Cannot Understand what is the Mistake here

Answer 1

You got exception because you have mail without subject. Statement should be corrected with ;

if(message.getSubject() != null && message.getSubject().contains([Keyword]))  

Answer 2

Your code is full of these common JavaMail mistakes , please correct them.

There's no need to create your own custom SearchTerm, just use SubjectTerm :

SearchTerm search = new SubjectTerm(keyword);