Milinda Pro

Revert Ubuntu boot loader after installing Window 7

This post will describe to install Ubuntu GRUB boot loader after installing windows 7 on a PC that already Ubuntu installed. Also this is a problem that I faced after installing Windows 7. Suddenly my Windows 7 installation was crashed and I formatted Windows installed drive and reinstall the Windows 7. I was used Windows and Ubuntu installed on different drives as a dual boot. But after installing windows 7 Ubuntu boot loader was overwritten by windows boot loader and that boot loader does not list my Ubuntu installation. Therefore I could not select Ubuntu to load and windows boot loader automatically boot the Windows7 itself. To overcome this problem we have to overwrite GRUB boot loader on windows boot loader. Follow the steps that I explained bellow correctly to do that.

This method will copy boot settings from Ubuntu Live-CD in order to boot from GRUB boot loader.

Step1- Insert Ubuntu Live CD into CD drive and boot from it.

Step2- Click on 'Try Ubuntu' (on Ubuntu 11.04) to load Ubuntu from Live CD without affecting to your computer.

Step3- When Ubuntu Live desktop appear Run 'Terminal' (Application-->Accessories-->Terminal) to execute following commands.
Step4- In terminal type sudo fdisk -l
It will display all partitions on the hard disk with some details

Identify the partition which Ubuntu installed by checking 'System' column from the above result. The partition which has 'Linux' under system column is the partition of Ubuntu installed.

But here(in my computer) 3 partitions hold 'Linux' under system column. Therefore you should identify the correct partition. For that you can use 'Disk utility' software(it is already included in Live-CD session). Still complicated to identify the partition please be patient, it can be identify in next step.

Step5- Mount the Ubuntu partition drive
sudo mount /dev/sdXX /mnt
(Example- sudo mount /dev/sda9 /mnt)

Now go to Home directory(Place-->Home), go to root directory and go to mnt directory by double clicking. Make sure here the folders such as 'boot', 'opt', 'usr' and 'bin' etc exists on this directory(/mnt directory). If not you could not mount Ubuntu installed partition to the mnt, so unmount it and mount the correct partition to the mnt.(To unmount type sudo unmount /mnt)

Step6- If you have different partitions for boot, home, etc... mount them to each corresponding directory in /mnt directory.
Example- sudo mount /dev/sda3 /mnt/boot

sudo mount /dev/sda10 /mnt/home

(to check whether you mount correct partition to the correct directory check out the content of each directories)

Step7- Now all the files that are required had mounted and ready to install GRUB boot loader.

sudo grub-install --root-directory=/mnt /dev/sda

(Note-That's /dev/sda the hard disk itself, not Ubuntu installed partition)
If it says grub-install is not a command then you had some mistake on mounting.

Step8- Unmount and restart
unmount all the partitions that mounted.
Restart the computer - sudo reboot

That's it. Now you can see the GRUB boot loader with all the installed operating system listed.

Use Android phone as a modem (Internet connection to PC through Android phone)

First of all I would like to say happy new year to all of you. So this is my first post in 2012.

This post is based on a problem that I faced after -->brought an Android phone. Oh I forgot to say you, I brought an Android phone it is Sony Ericsson Experia X10 mini pro. The problem that I faced is 'How to connect this phone and establish a internet connection in PC'. You know most of the normal phone that capable GPRS can connect to PC(USB or bluetooth) and establish the internet connection over phone. Earlier I used a Nokia phone(Nokia 3120 classic). It can be used as a modem to pc, therefore I could brows internet in PC through the phone.
But in this Android phone it is a little bit different. Because this is an Android phone *#%@.=+.

Simply here are steps to configure your Android phone as a modem.

First of all you have to download and install software needed in both sides, phone and PC. This task is just like a client-server application. So first, lets install on the phone.

The software is EasyTether. EasyTether allows you to shares your phone Internet connection with computer/laptop/notebook (Windows 7/Vista/XP 64-bit/32-bit, Mac OS X 10.4/10.5/10.6/10.7, Ubuntu 10.4+, Fedora 13+)

you can download Easy Tether from Android market and install it from your phone it self. But there is a thing to say you this is not a Free software. But Lite version of Easy Tether is available in Android market but the latest version of the EasyTether Lite has some restrictions since it is lite version. Such as blocking secure HTTP sites....... Therefore this is not a complete solution. But there is a way to Activate the EasyTether. Follow these steps to achieve the EasyTether.

The older version of the EasyTether has the Activation code for full version. Therefore you have to install an older version of Easy tether to get the code.

First download EasyTether 0.9.3 apk file from here or here.
Install the apk file manually to the phone.
Open the EasyTether from the phone ans just go to 'About' page and write down 5 digit code (under 'Registration code'). So this is the activation code for your phone.
Now uninstall EasyTether 0.9.3 from your phone to install latest version.
Install latest version of the EasyTether Lite version(free version)from the Android market.
Open it. In first start, EasyTether will show a dialog box about a setup wizard or some thing like that. Just cancel it(You can get it later from setup) and tap on 'Activate EasyTether' to activate the product.
Here you should type the 5 digit number which you written under 'Activation code'
Now you have the full version of the EasyTather with all capabilities.

Now tap on 'Setup/Settings' and tap on 'USB Tethering setup' to configure your computer for EasyTether. now a setup wizard for the configuration will open and you can easily follow the instruction. This setup wizard is more descriptive and easy. Therefore I think that is no need to explain these steps here. Additionally you have to download the EasyTether software for PC.(The setup wizard will inform you to download and install it to your PC).

Additionally make sure the network drivers installed on your PC. In Windows you can be found it in 'Device manager' under 'Network adapters' named 'Easy Tether Network Adapter'.

Finally you will be able to connect to internet through your Android phone.

To establish the connection just plug USB cable and click on 'Connect' by right click on the EasyTether icon from sys tray in Windows.

Hibernate operations (Data Deletion) - Part 4

Hibernate is an object-relational mapping (ORM) library for the Java language. Hibernate provides data query and retrieval facilities that significantly reduce the development time. Hibernate facilitates you to develop persistent classes following an object-oriented styles such as inheritance, polymorphism, composition, association, and collections.

This article only concern about data retrieving through hibernate. (Data insertion article can be found at Part 1 of this series and data update article can be found at Part 2 of this article series)

And also I have to mention here this article not describing all the hibernate from the beginning. Therefore this is not the best way to start your first hibernate java project. Simply this article very much suitable for the people those who having basis of the hibernate.

To start these all the sample programs you should do the initial thing such as adding related jar files, referring those jars, establish MySql db connection(from eclipse or netbeans to view db's data), etc.

Initiating............
First let's create java class which used as a persistent class.
Create a java class named "Person.java"


package pkg;
import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class Person {
 private int id;
 private String name;
 private int age;

 @Id
 public int getId() {
  return id;
 }
 public void setId(int id) {
  this.id = id;
 }
 public String getName() {
  return name;
 }
 public void setName(String name) {
  this.name = name;
 }
 public int getAge() {
  return age;
 }
 public void setAge(int age) {
  this.age = age;
 }
}

This class is now persistent class through annotations.
(This class is identical to the class that we used in part 1)

Data Deletion

Before writing codes for data deletion, you should have a knowledge about HQL for the hibernate. This HQL can be use to data retrieve,update and delete from db. If you do not have at least basis of the HQL please refer part 2 of this article series.

So, now let move to data deletion, this deletion is also a some kind of update to the db. Because deletion means removing specific field or fields from a table by changing its status (status means number of fields, file size, etc). Therefore the method that we used for update the db can be used for data deletion also. Here code for data deletion is not much differ from data updating.

Therefore the HQL query for data deletion is,


delete from Person

If we use this query itself for data deletion, the query will delete the current element from the table. But this thing won't be used for practical scenarios. Therefore we have to let it know 'what records to be deleted' by executing the query.

HQL query for data deletion with conditions


delete from Person as p where p.id = :key

Here I used the parameter(if you can remember) for this query named 'key'. (Need 'what is the parameter?' please refer part2 of this article series). Therefore the complete java code for this query is,


String searchId = "1";

String query = "

delete from Person as p where p.id = 
:key

";



session.createQuery(query).setString("key",

searchId).executeUpdate()

Simply this is the way to update the database also, only change of this code is the word 'delete' in the query. Isn't it easy?...........But finally remember to commit the operation because 'we change the database's data'.

The complete java code for data deletion is,




package pkg;

import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.classic.Session;
import org.hibernate.tool.hbm2ddl.SchemaExport;

public class TestPerson {

    public static void main(String[] args) {
        
        AnnotationConfiguration config = new AnnotationConfiguration();
        config.addAnnotatedClass(Person.class);
        config.configure("hibernate.cfg.xml");
        
        SessionFactory factory = config.buildSessionFactory();
              
        //beginning of the session
        Session session = factory.openSession();
        session.beginTransaction();//beginning of the transaction

String searchId = "1";

//this is the key id for field being updated
        
        //create the delete query

String query = "

delete from Person as p where p.id = 
:key

";

session.createQuery(query).setString("key",

searchId).executeUpdate();

        session.getTransaction().commit();//end of transaction
        session.close();//end of  session
        
        
        }

}

If you execute this code segment the field with id of "1" will be deleted (if exist).
Also I have to mention here the method createQuery() will return the number of fields that it changed by executing the query. Therefore if you want to get the number of fields that changed or check whether any changes had been done by the query, you can use that number. To do that first assign the number return by method to the int variable.


int fieldCount = session.createQuery(query).setString("key", searchId).executeUpdate();

After that you can use this variable for get the number of fields that changed or check whether any changes had been done by the query.

For example,


int fieldCount = session.createQuery(query).setString("key", searchId).executeUpdate();

if(fieldCount > 0)
    System.out.printf("Number of fields changed %d\n", fieldCount);
else
    System.out.printf("No changes had been done\n");

Hmmmmm.... so this is the last article for hibernate operation article series. If you go through all the parts of this article series you will be able to do basic hibernate operations such as,

Data insertion.
Data updating
Data retrieving
Data deletion.

Hibernate operations (Data Retriving) - Part 3


package pkg;
import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class Person {
 private int id;
 private String name;
 private int age;

 @Id
 public int getId() {
  return id;
 }
 public void setId(int id) {
  this.id = id;
 }
 public String getName() {
  return name;
 }
 public void setName(String name) {
  this.name = name;
 }
 public int getAge() {
  return age;
 }
 public void setAge(int age) {
  this.age = age;
 }
}

This class is now persistent class through annotations.
(This class is identical to the class that we used in part 1)

Data Retriving
Before writing codes for data retrieving, you should have a knowledge about HQL for the hibernate. This HQL can be use to data retrieve from db. If you do not have at least basis of the HQL please refer part 2 of this article series.

It is very easy to retrieve data from the db by just executing HQL query but getting data in java program from the result of the executed query is some what hard.

The query for retrieve all data from Person class is,


from Person

This query can be execute by executing following java code segment.


String query = "from Person";

session.createQuery(query);

These codes will be executed successfully but where is the result which returned from the executed query?
In hibernate the result of the HQL query can be caught by java.util.List. Therefore code for retrieving data can be update as follows.

Now list object hold the all of data which return from the executed query.

Now let's see how to access to the list in order to get the real data. To acquire this we have to use java.util.Iterator class. So do not forget this is Hibernate(a ORM tool) therefore we can use getters from 'Person' class to get the particular data. If we going to use getters, it should be included some data into instance variables in the class. Therefore we can assign data into Person type object.

String query = "from Person";
List list = session.createQuery(query).list();
        
Iterator iterator = list.iterator();


Person obj = (Person) iterator.next();//cast and assign data to Person type object


System.out.print(obj.getId() + "\t" + obj.getAge() + "\t" + obj.getName() + "\n");

We can use while loop to view all data on the result set.

String query = "from Person";
List list = session.createQuery(query).list();
        
Iterator iterator = list.iterator();



while (iterator.hasNext()) {
        Person obj = (Person) iterator.next();//cast and assign data to Person type object
            
        System.out.print(obj.getId() + "\t" + obj.getAge() + "\t" + obj.getName() + "\n");
}

Also you can implement conditional retrieving using 'where' keyword.

String searchId = "1";

String query = "from Person as p where p.id = :sId";
List list = session.createQuery(query)
        .setString("sId", searchId).list();
        
Iterator iterator = list.iterator();
        
while (iterator.hasNext()) {
        Person obj = (Person) iterator.next();//cast and assign data to Person type object
            
        System.out.print(obj.getId() + "\t" + obj.getAge() + "\t" + obj.getName() + "\n");
}

The complete java code for data retrieving is,


apackage pkg;

import java.util.Iterator;
import java.util.List;

import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.classic.Session;
//import org.hibernate.tool.hbm2ddl.SchemaExport;

public class TestPerson {

    public static void main(String[] args) {

        AnnotationConfiguration config = new AnnotationConfiguration();
        config.addAnnotatedClass(Person.class);
        config.configure("hibernate.cfg.xml");
              
        SessionFactory factory = config.buildSessionFactory();
        Session session = factory.getCurrentSession();

session.beginTransaction();


        String searchId = "1";
        String query = "from Person as p where p.id = :sId";
        List list = session.createQuery(query)
                    .setString("sId", searchId).list();
        
        Iterator iterator = list.iterator();
        
        while (iterator.hasNext()) {//is next data exist? then loop
            Person obj = (Person) iterator.next();//cast and assign next data to Person type object
            
            System.out.print(obj.getId() + "\t" + obj.getAge() + "\t" + obj.getName() + "\n");
        }
        
        session.close();

Now as an example let's consider our table data are looks like this,

+----+-----+-------------------+
| id | age | name              |
+----+-----+-------------------+
|  1 |  23 | Milinda           |
|  2 |  24 | Milinda Aruna     |
|  4 |  25 | Aruna Milinda UWU |
|  5 |  25 | Aruna UWU Milinda |
+----+-----+-------------------+

The output of this code segment is,

1 23 Milinda

Related posts

Hibernate operations (Data Update) - Part 2

Hibernate is an object-relational mapping (ORM) library for the Java language. Hibernate provides data query and retrieval facilities that significantly reduce the development time. Hibernate facilitates you to develop persistent classes following an object-oriented styles such as inheritance, polymorphism, composition, association, and collections.

This article only concern about data update through hibernate. (Data insertion article can be found at Part 1 of this series)

And also I have to mention here this article not describing all the hibernate from the beginning. Therefore this is not the best way to start your first hibernate java project. Simply this article very much suitable for the people those who having basis of the hibernate.

To start these all the sample programs you should do the initial thing such as adding related jar files, referring those jars, establish MySql db connection(from eclipse or netbeans to view db's data), etc.

Initiating............
First let's create java class which used as a persistent class.
Create a java class named "Person.java"


package pkg;
import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class Person {
 private int id;
 private String name;
 private int age;

 @Id
 public int getId() {
  return id;
 }
 public void setId(int id) {
  this.id = id;
 }
 public String getName() {
  return name;
 }
 public void setName(String name) {
  this.name = name;
 }
 public int getAge() {
  return age;
 }
 public void setAge(int age) {
  this.age = age;
 }
}

This class is now persistent class through annotations.
(This class is identical to the class that we used in part 1)

Data Update
Before writing codes for updating let me introduce the HQL for the hibernate. This HQL can be use to update the db. It is essential to get know about HQL before move to further operations of hibernate.

HQL - The Hibernate Query Language
HQL is similar in appearance to SQL that can be used as a a powerful query language for Hibernate.HQL is a case insensitive query language. Therefore as an example the keyword fRoM, FrOm, from and FROM are identical for a query.

The first HQL query.

from: from is the simplest possible Hibernate query. Let's clarify this by using few examples.

from Person

This will return all the data from Person table. The equaling sql query is,

/*this is equaling sql query for 'from Person'*/ select * from Person

In order to refer to the Person in other parts of the query, you can assign an alias for Person using 'as' keyword.

from Person as P /*Now P refer the Person table*/

Also this can be acquired without using 'as' keyword.

from Person P /*Now P refer the Person table*/

Parameters: These parameters can be used within the the query to pass values when they are executing in the java program.

The sign : used to define the parameters.

from Person as p where p.id = :personId

Here 'personId' is a parameter. Now lets execute a HQL query in java. Basically to execute a HQL query the method 'createQuery' in the class 'org.hibernate.classic.Session' is used.

String searchId = "1"; String query = "from Person as p where p.id = :personId"; session.createQuery(query).setString("personId", searchId);

When call the method 'createQuery' the value of 'searchId' will assign to the parameter 'personId' in the query. Finally the query for execute is,

from Person as p where p.id = 1

Now let's combine update and these 2 concepts to execute the update query. 'createQuery' method can be used execute the update query. A update query uses the keyword 'update' as follows

'keyId' is a parameter for the query which can be used to pass a value when it execute.

The complete java program for the update is,




package pkg;

import java.util.Iterator;
import java.util.List;

import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.classic.Session;
import org.hibernate.tool.hbm2ddl.SchemaExport;

public class TestPerson {

    public static void main(String[] args) {
        
        AnnotationConfiguration config = new AnnotationConfiguration();
        config.addAnnotatedClass(Person.class);
        config.configure("hibernate.cfg.xml");
        
        SessionFactory factory = config.buildSessionFactory();
              
        //beginning of the session
        Session session = factory.openSession();
        session.beginTransaction();//beginning of the transaction
        
        String name = "New_Milinda";//this is new name for 'id'
        String id = "1";//this is the key id for field being updated
        
        //create the update query
        String query = "update Person as p set p.name = :newName where p.id = :keyId";
        
        session.createQuery(query)
            .setString("newName", name)//this will set the string 'newName' to name variable
            .setString("keyId", id)
            .executeUpdate();

        session.getTransaction().commit();//end of transaction
        session.close();//end of  session
        
        
        }

}

After this code segment run the data's which having id equal 1 will change its name into 'New_Milinda'. Here I used 'where' keyword to implement the condition for the update. (similar method used in mysql queries)

Finally the query to be executed is,


update Person as p set p.name = New_Milinda where p.id = 1

Also this is the query after setting all the parameters(newName and keyId).

I hope to post more articles for other operations of hibernate such as

Data retrieve
Data delete

from the db. Will be soon........

Related posts

Hibernate operations (Data insertion) - Part 1

Hibernate is an object-relational mapping (ORM) library for the Java language. Hibernate provides data query and retrieval facilities that significantly reduce the development time. Hibernate facilitates you to develop persistent classes following an object-oriented styles such as inheritance, polymorphism, composition, association, and collections.

This article only concern about data insertion to the db through hibernate.

And also I have to mention here this article not describing all the hibernate from the beginning. Therefore this is not the best way to start your first hibernate java project. Simply this article very much suitable for the people those who having basis of the hibernate.

Hibernate is a ORM tool. Therefore it is not necessary to care about db type (whether MySql or derbydb or another) when you programming a application for a db. But you have to concern only about the 'connection.driver_class' and 'connection.url' in the 'hibernate.cfg.xml' file to match the db type.

Therefore you can change your database type at anytime without changing whole java codes or queries written for da operations. It is the power of Hibernate.

To start these all the sample programs you should do the initial thing such as adding related jar files, referring those jars, establish MySql db connection(from eclipse or netbeans to view db's data), etc.

Initiating............
First let's create java class which used as a persistent class.
Create a java class named "Person.java"


package pkg;
import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class Person {
 private int id;
 private String name;
 private int age;

 @Id
 public int getId() {
  return id;
 }
 public void setId(int id) {
  this.id = id;
 }
 public String getName() {
  return name;
 }
 public void setName(String name) {
  this.name = name;
 }
 public int getAge() {
  return age;
 }
 public void setAge(int age) {
  this.age = age;
 }
}

This class is now persistent class through annotations.

Data insertion
Data insertion can be done using this persistent class's object. Following sample code shows the way to insert data to a database through hibernate.

Create a java class named "TestPerson.java" with main method.


package pkg;

import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.classic.Session;
import org.hibernate.tool.hbm2ddl.SchemaExport;

public class TestPerson {

 public static void main(String[] args) {

  //create configurations for Person class
  AnnotationConfiguration config = new AnnotationConfiguration();
  config.addAnnotatedClass(Person.class);
  config.configure("hibernate.cfg.xml");

  //create new schema(db and table)
  new SchemaExport(config).create(true, true);//comment this line if you already created the table Person
  
  SessionFactory factory = config.buildSessionFactory();
  Session session = factory.getCurrentSession();
  
  session.beginTransaction();//begin the db operations
  
  //Insertion to the table
  Person person = new Person();//create the object from persistent class
  //set data that you want to store in db
  person.setId(1);
  person.setName("Milinda");
  person.setAge(24);
   
  session.save(person);//save the object to db
  
  session.getTransaction().commit();//save permanently to db(end of db operations)
 }
}

Now data(id=1, name=Milinda and age=24) will be stored in the 'Person' table. Finally the 'Person' table's data can be shows as follows.

+----+-----+----------+
| id | age | name     |
+----+-----+----------+
|  3 |  24 | Milinda  |
+----+-----+----------+

Note- You can remove(or comment) the code line new SchemaExport(config).create(true, true); if you already create the db and particular tables.(This code line responsible for create tables on th db)

I hope to post more articles for other operations of hibernate such as

Data update
Data retrieve
Data delete

from the db. Will be soon........

Related posts

Add Hibernate javadoc to eclipse

Javadoc is a convenient way to learn and get help from documents which are provided by the programmer. These javadoc can be added to Eclipse IDE to view appropriate javadoc for a particular class or method or interface etc. These javadocs views on eclipse when auto complete (or content assist) appear. You can view the content assist by pressing 'Ctrl+Space'.

You can see the javadoc window on right hand side of this figure.

By default the javadoc for hibernate distribution does not exists. To add the javadoc to eclipse follow these steps.

Step 1
Download javadoc jar file from following link
hibernate-3.2.2.ga-javadoc.jar
Any how you should download the hibernate-3.2.2.ga-javadoc.jar file.

Step2
Open eclipse and add above jar file to hibernate3.jar as a javadoc for it. To do that follow the steps explained below.

Step 3
Right click on 'hibernate3.jar' by expanding user library which contain all your hibernate reference jar files. And select 'Properties'.

Step 4
Select 'Javadoc Location' from side pane and click on 'Javadoc in archive' to select it.

Step 5
Browse for downloaded jar file and add that jar file location as javadoc location for 'hibernate3.jar'.

Step 6
Click 'Apply' and 'OK' to save the changes.

Now it is done you can view javadoc from eclipse.

Usefull PIC programming tips for PIC16f877A

This article totally depends on my experiences when I doing some microcontroller projects based on PIC16f877A. Further more following article describe the answers which I found for following questions.

Make RA4(4th bit of PORTA) as a digital output.

All the bits on all the ports in PIC16f877A microcontroller can be configure as digital input or output except RA4. All other bits on ports can be configure as a digital I/O by changing its TRIS register's values and configuring ADCON1 register(for analog input pins). But if we consider about RA4 pin, its behavior different than other I/O pins.

RA4 is an open collector I/O pin. Therefore when we want to use RA4 as a digital output, we have to pull up RA4 by a resistor. This approach can be understand by following example.

This is an example program to use RA4 as a digital output using Hi-Tech C.



#include <htc.h>

#define _XTAL_FREQ 4000000

void main(){

    TRISA = 0;//PORTA is output

    

    //configure ADCON1 to set PORTA as digital I/O

    PCFG0 = 0;

    PCFG1 = 1;

    PCFG2 = 1;

    PCFG3 = 0;

    

    ADON = 0;//ADC modulde is off

    

    while(1){

        RA4 = 1;//Now LED will off

        __delay_ms(100);

        __delay_ms(100);

        __delay_ms(100);

        RA4 = 0;//Now LED will on

        __delay_ms(100);

        __delay_ms(100);

        __delay_ms(100);

    }

}

Finally what we have to do is, supply a current to LED attached to RA4 and change the logic to on and off the LED.

Status on RA4	LED status
1 (High)	Off
0 (Low)	On

References and further readings-

The best source for understand the behavior of the PIC is "Data sheet".

This is a cropped part from PIC16f877A data sheet.

Make RB3(3rd bit of PORTB) as a digital Input

All the bits on PROTB can be used as digital input except RB3. Because by default the Low-Voltage ICSP Programming (LVP) is enabled in PIC16f877A which lead to disable RB3 I/O function. If you do not use LVP, you can disable LVP by following these steps in MPLAB IDE.

Configure
Configuration bit.
Uncheck Configuration Bits set in code.
Select disable on LVP field.
Close and recompile the code.

Now you can use RB3's input function by changing TRISB's 3rd bit into 1.(TRISB3 = 1)

References and further readings-

The best source for understand the behavior of the PIC is "Data sheet".

This is a cropped part from PIC16f877A data sheet.

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