Forcing “portrait” orientation mode for android application

Adding following code segment in AndroidManifest file for each activity, we can force the android application to work only in portrait mode.

Note: Don't apply the orientation to the application element, instead you should apply the attribute to the activity element, and you must also set configChanges as noted below.

<activity
   android:screenOrientation="portrait"
   android:configChanges="orientation|keyboardHidden">
</activity>

Java Interview Question: HashSet vs HashMap

HashSet

1. HashSet class implements the Set interface
2. In HashSet, we store objects(elements or values) e.g. If we have a HashSet of string elements then it could depict a set of HashSet elements: {“Hello”, “Hi”, “Bye”, “Run”}
3. HashSet does not allow duplicate elements that mean you can not store duplicate values in HashSet.
4. HashSet permits to have a single null value.
5. HashSet is not synchronized which means they are not suitable for thread-safe operations until unless synchronized explicitly. 

HashMap

1. HashMap class implements the Map interface
2. HashMap is used for storing key & value pairs. In short, it maintains the mapping of key & value (The HashMap class is roughly equivalent to Hashtable, except that it is unsynchronized and permits nulls.) This is how you could represent HashMap elements if it has integer key and value of String type: e.g. {1->”Hello”, 2->”Hi”, 3->”Bye”, 4->”Run”}
3. HashMap does not allow duplicate keys however it allows having duplicate values.
4. HashMap permits single null key and any number of null values.
5. HashMap is not synchronized which means they are not suitable for thread-safe operations until unless synchronized explicitly. 

How to handle HTTP Header related issue in Apache

By following below steps you can suppress following HTTP Header related security issues in web applications those are hosted in apache web server.

• Web Browser XSS Protection Not Enabled
• X-Frame option Header not set
• X-Content-Type-Options header missing  
• Incomplete or No Cache-control and Pragma HTTP Header Set

These issues can be handled by placing following lines in httpd.conf of apache web server.

Header set X-XSS-Protection “1; mode=block”
Header set Strict-Transport-Security "max-age=31536000; includeSubDomains; preload"
Header always append X-Frame-Options DENY
Header set X-Content-Type-Options nosniff
Header set Content-Security-Policy "default-src 'self';"

For this mod_hedaers module also need to be enabled. so uncomment the following Load Module line:

LoadModule headers_module modules/mod_headers.so

Now doing security audit test again, you can see these issues are handled properly. 

Handling HTTP Header related security issues in Tomcat 8 web applications

The following issues are the commonly occurs in security audit report of any java web applications

• Web Browser XSS Protection Not Enabled
• X-Frame option Header not set
• X-Content-Type-Options header missing  
• Incomplete or No Cache-control and Pragma HTTP Header Set

Tomcat 8 provides, support for following http header 

• X-Frame-Options – to prevent clickjacking attack
• X-XSS-Protection – to avoid cross-site scripting attack
• X-Content-Type-Options – block content type sniffing
• HSTS – add strict transport security

To utilize this option we need to follow simple steps. Just uncomment the following lines in Tomcat's web.xml files (\conf\web.xml).

<filter>
     <filter-name>HeaderSecurityFilter</filter-name> 
     <filter-class>org.apache.catalina.filters.HttpHeaderSecurityFilter</filter-class>
 </filter>
<filter-mapping>
      <filter-name>HeaderSecurityFilter</filter-name>
      <url-pattern>/*</url-pattern>
 </filter-mapping>

Remember it is not applications individual web.xml files. it is tomcat's web.xml. after uncommenting these lines. restart the tomcat and redo the security audit. you can see the issues are handled.

'gradle' is not recognized as an internal or external command

Following steps need to be followed for fixing: "'gradle' is not recognized as an internal or external command" error.

1.  Download the zipped file of Gradle from https://services.gradle.org/distributions/gradle-2.8-all.zip. 
2. Unzip them and place them in your Windows machine at any specific location. For e.g. “C:\Program Files\”. 
3. Click on the Windows button at the left bottom of the desktop. 
4. Right-click on “Computer” and click on “Properties”. This will open the Control Panel. 
5. Click on “Advanced System settings” and then click on “Environment Variables” button. 
6. Click on “New…” button under the “System Variables” section and enter Variable name as ‘GRADLE_HOME’. 
7. Provide the path of the Gradle file as Variable value, i.e. C:\Program Files\gradle-2.8 
8. Click OK. 
9. Select “path” variable under the “System Variables” section and click on “Edit” button. 
10. Go to the end of variable value and add “;%GRADLE_HOME%\bin” and click on “OK” button. 
11. Press “Windows + R” and type ‘cmd’. Click OK. 
12. Type the command “gradle –v” on the command prompt. 
13. Now the screen displays the version of the Gradle. This means that the Gradle is successfully configured on the given Windows machine.

Escape Special chracters in java

Following code escaps the special meaning of characters before showing in XML or in view

 public static String escapeText(String s) {
   
    if (s.indexOf('&') != -1 || s.indexOf('<') != -1
     || s.indexOf('>') != -1 || s.indexOf('"') != -1
     || s.indexOf('\'') != -1 ) {
      StringBuffer result = new StringBuffer(s.length() + 6);
      for (int i = 0; i < s.length(); i++) {
        char c = s.charAt(i);
        if (c == '&') result.append("&amp;");
        else if (c == '<') result.append("&lt;");
        else if (c == '"') result.append("&quot;");
        else if (c == '\'') result.append("&apos;");
        else if (c == '>') result.append("&gt;");
        else result.append(c);
      }
      return result.toString();  
    }
    else {
      return s;   
    }
        
  }

HTML 5 logo unveiled by W3C

Imagination, meet implementation. HTML5 is the cornerstone of the W3C's open web platform; a framework designed to support innovation and foster the full potential the web has to offer. Heralding this revolutionary collection of tools and standards, the HTML5 identity system provides the visual vocabulary to clearly classify and communicate our collective efforts.


W3C unveiled today an HTML5 logo, a striking visual identity for the open web platform. W3C encourages early adopters to use HTML5 and to provide feedback to the W3C HTML Working Group as part of the standardization process. Now there is a logo for those who have taken up parts of HTML5 into their sites, and for anyone who wishes to tell the world they are using or referring to HTML5, CSS, SVG, WOFF, and other technologies used to build modern Web applications. The logo home page includes a badge builder (which generates code for displaying the logo), a gallery of sites using the logo, links for buying an HTML5 T-shirt, instructions for getting free stickers, and more. The logo is available under "Creative Commons 3.0 By" so it can be adapted by designers to meet their needs.