What is Mercurial ?

Mercurial is a fast, lightweight Source Control Management system designed for efficient handling of very large distributed projects. It is mainly implemented using the Python programming language. It is supported on Windows and Unix-like systems, such as Mac OS X and Linux.

All of Mercurial's operations are invoked as arguments to its driver program hg, a reference to the chemical symbol of the element mercury.

Mercurial's major design goals include high performance and scalability, decentralized, fully distributed collaborative development, robust handling of both plain text and binary files, and advanced branching and merging capabilities, while remaining conceptually simple. 

How you can benefit from Mercurial

1. It is fast and powerful, It efficiently handles projects of any size and kind. Every clone contains the whole project history, so most actions are local, fast and convenient.
   
2. Mercurial supports a multitude of workflows and you can easily enhance its functionality with extensions.
   
3. It is easy to learn and use
   
4. It is lightweight.
   
5. It scales excellently.

How to read certificates using CertificateFactory class

In my previous blog, I have explained how can you create self signed certificate using bouncy castle API and how to import it into keystore.

This tutorial will explain how to read existing certificate file using java.security.cert.CertificateFactory class.


import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.security.KeyStore;
import java.security.PublicKey;
import java.security.cert.Certificate;
import java.security.cert.CertificateFactory;

/**
 * Reads the certificate and import into Java keystore.
 *
 * @author abdul
 *
 */
public class ReadCertificateFile {

    /**
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception {

        ReadCertificateFile readCertificateFile = new ReadCertificateFile();

        // Path of the certificate file
        FileInputStream fis = new FileInputStream("YOUR_CERTIFICATE.cert");

        /*
         * Returns a CertificateFactory object of the specified certificate
         * type.
         */
        CertificateFactory cf = CertificateFactory.getInstance("X.509");
       
        /*
         * Read the certificate from the specified input stream, and returns it
         * as a Certificate object. It can read certificate in both binary (DER
         * encoded) and printable (RFC standard) formats.
         */
        java.security.cert.Certificate cert = cf.generateCertificate(fis);

        System.out.println();
        System.out.println("Certificate Details: ");
        /*Returns the type of this certificate factory*/
        System.out.println("Type = " + cert.getType());
       
        System.out.println("toString = " + cert.toString());

        PublicKey key = cert.getPublicKey();
        System.out.println();
        System.out.println("PublicKey Object Info: ");
        System.out.println("Algorithm = " + key.getAlgorithm());
        System.out.println("Format = " + key.getFormat());
        System.out.println("toString = " + key.toString());

        // save/import certificate into keystore
        readCertificateFile.saveCert(cert);
    }

    private void saveCert(Certificate cert) throws Exception {
        KeyStore keyStore = KeyStore.getInstance("JKS");
        keyStore.load(null, null);

        // import your certificate into keystore
        keyStore.setCertificateEntry("YOUR_ALIAS_NAME", cert);

        // name of keystore "
        File file = new File(".", "YOUR_KEYSTORE_NAME");
        keyStore.store(new FileOutputStream(file),
                "YOUR_PASSWORD".toCharArray());
    }

}

Eclipse - Tips & Tricks

This article is for those who use Eclipse. Keyboards shortcuts are very important for comfortable and quick editing. Here are the list of most important shortcuts in Eclipse :

For a full list of shortcuts, you can also check by pressing Ctrl+Shift+L.

1. Ctrl +3 Focus into the Quick Access search box which allows you to execute any Eclipse command.
2. Ctrl+SHIFT+T Search dialog for Java Type, Start typing the name and the list gets smaller. Try typing the capital letters of the class only (e.g. type "NPE" to find "NullPointerException")
3. Ctrl+SHIFT+R Search dialog for resources, e.g. Xml files, text files, or files of any other type.
4. Ctrl+E Open Editor Drop down, Presents a popup window listing currently opened files.
5. Ctrl+O Quick Outline, Show all methods of the current class, Press Ctrl+O a second time to include inherited methods.
6. Ctrl+SHIFT+space Context Information
7. Ctrl+Shift+O Organize Imports, Adjusts the imports statements in the current Java source file
8. F3 Open Declaration ,Navigate to the declaration of the selected variable . This works much like a browser hyperlink.
9. Ctrl + hover to methods,variables Ask for Open Declaration, Implementation, Super Implementation or return types.
10. Alt+Left/Right Backward/Forward History, Works like a browser's back/forward button.
11. Ctrl + L Go to a specific line number.
12. F4 Open Type Hierarachy
13. Ctrl+Alt+H Open Call Hierarchy. Show where a method is called from.
14. Alt + SHIFT + R Use this to rename type, method, or field. All existing references will be refactored as well.
15. Alt+Shift+M Extract method, Use this to extract a new method from existing code. The parameter list and return type will be automatically created.
16. Ctrl+Shift+P Go to the matching bracket.
17. SHIFT+ENTER /Ctrl+SHIFT+ENTER Insert a line below or above the current line.
18. Ctrl + /, Ctrl+7, Ctrl +\ Add or Remove block comment.
19. Ctrl +F6 Switch among the editor.
20. Ctrl + F7 Switch among open views.
21. Ctrl + F8 Switch among perspectives.
22. Alt +/ It does the word completion based on the set of words already present in the current file.
23. Ctrl + I It correct the indention for block of Java code or an entire class.
24. Ctrl + . or Ctrl + , It will navigate to next or previous error.
25. Ctrl+F11, F11, Run or Debug the Application.
26. F5,F6, F7, F8 Step into function, Next Step (line by line) , Step out , Skip to next breakpoint.
27. Ctrl +1 Give quick fix code.
28. Ctrl + D Delete the current line.
29. Ctrl + SHIFT + G Search for current cursor positioned word reference in workspace.
30. Ctrl +Page Up/Page Down Switch to next editor / switch to previous editor
31. Alt + - Open Editor Window Option menu.
32. Ctrl +F10, then n It will show or hide the line numbers
33. Ctrl + q It will jump to last location edited
34. Ctrl + SHIFT + f It will format all code in Editor using code formatter.
35. Alt + SHIFT + J or /** and then press Enter Add javadoc Element Comment ( adds '/** ... */')
36. Alt + SHIFT + V Move selected element to other class or file (With complete method or class selected)
37. Ctrl + DEL Delete next element
38. Ctrl + BACKSPACE Delete previous element. 
    Note : I have not added basic shortcut like Ctrl+S to save the file.
    Feel free to comment If you find something is incorrect or update me more :)