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Using Single HashMap we can Retrieve the Entire Row from Database using any Column value

Using this program we can get the entire row by giving any attribute value of that row by using only one Single HashMap and JavaBean. In  this program we used the JDBC connection  to the Database MySQL. we can alter the database table values using Collections.


package morning;

import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Scanner;


public class Until {
static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
static final String DB_URL = "jdbc:mysql://localhost:3307/organization";

// Database credentials
static final String USER = "root";
static final String PASS = "root";

public static void main(String[] args) throws SQLException,
ClassNotFoundException, IOException {
Connection conn = null;
Statement stmt = null;

try {
// STEP 2: Register JDBC driver
Class.forName("com.mysql.jdbc.Driver");

// STEP 3: Open a connection
System.out.println("Connecting to database");
conn = DriverManager.getConnection(DB_URL, USER, PASS);
            Scanner sc =new Scanner(System.in);
         
// STEP 4: Execute a query
System.out.println("Creating statement...");
stmt = conn.createStatement();
String sql;
sql = "select id,job,salary from employ;";
ResultSet rs = stmt.executeQuery(sql);

while (rs.next()) {
Employ z = new Employ();
int empid = (rs.getInt("id"));
String empjob = (rs.getString("Job"));
int salary = rs.getInt("salary");
z.setId(empid);
z.setJob(empjob);
z.setSalary(salary);
SearchEmp.add(z);
}
String key;
System.out.println("Enter the name you want to search ");
System.out.println("Enter 1. EmpId    2.Salary      3.Job");
int x=sc.nextInt();
switch(x)
{
case 1:
   System.out.println("Enter the EmpId");
      key=sc.next();
        SearchEmp.display(x,key);
        break;
     
case 2:   System.out.println("Enter the Salary ");
         key=sc.next();
                   SearchEmp.display(x,key);
                    break;
                 
case 3:       System.out.println("Enter Job");
         key=sc.next();
        SearchEmp.display(x,key);
        break;
}
}
catch(Exception e)
{
e.printStackTrace();
}

}
}

Using the JavaBean we can get the entire user defined set of attributes(datatypes) under single object.

1. A JavaBean Must have Setter and Getter Methods
2. It must be implemented by serializable.
3. It must have a Constructor.

In this Program we are sorting based on their Job Category and Based on their Salary also. In this we taken Java Bean as object to sort the database table.We used Comparator for sorting and Employee type objects are stored in ArrayLists for Sorting.

package com.nt.finals;

import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;

class Justify {

public static ArrayList<Employ> ald = new ArrayList<Employ>();
public static ArrayList<Employ> alt = new ArrayList<Employ>();

public static void add(Employ z) {

// TODO Auto-generated method stub
alt.add(z);}


public static void add1(Employ z) {
ald.add(z);

}
public static void display()
{
Collections.sort(ald, new Comparator<Employ>() {

@Override
public int compare(Employ o1, Employ o2) {
// TODO Auto-generated method stub
if(o1.getSalary()>o2.getSalary())
return 1;
else
return -1;
}

});

for (Employ emd : ald) {

System.out.println(emd);
}
Collections.sort(alt, new Comparator<Employ>() {

@Override
public int compare(Employ o1, Employ o2) {
// TODO Auto-generated method stub
if(o1.getSalary()>o2.getSalary())
return 1;
else
return -1;
}

});

for (Employ em : alt) {

System.out.println(em);
}



}
}

public class Hazard {

static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
static final String DB_URL = "jdbc:mysql://localhost:3307/organization";

// Database credentials
static final String USER = "root";
static final String PASS = "root";

public static void main(String[] args) throws SQLException,
ClassNotFoundException, IOException {
Connection conn = null;
Statement stmt = null;

try {
// STEP 2: Register JDBC driver
Class.forName("com.mysql.jdbc.Driver");

// STEP 3: Open a connection
System.out.println("Connecting to database");
conn = DriverManager.getConnection(DB_URL, USER, PASS);

// STEP 4: Execute a query
System.out.println("Creating statement...");
stmt = conn.createStatement();
String sql;
sql = "select id,job,salary from employ;";

ArrayList<Employ>ald=null;
ArrayList<Employ>alt=null;
ArrayList<Employ> al = new ArrayList<Employ>();
ResultSet rs = stmt.executeQuery(sql);
Justify zx = new Justify();

while (rs.next()) {
Employ z = new Employ();
int empid = (rs.getInt("id"));
String empjob = (rs.getString("Job"));
int salary = rs.getInt("salary");
z.setId(empid);
z.setJob(empjob);
z.setSalary(salary);
al.add(z);
String strs = "Tester";
String x = "Developer";
if (empjob.trim().equals(x)) {
zx.add1(z);
}

else if (empjob.trim().equals(strs)) {
zx.add(z);

}

System.out.println(z);

}
System.out.println("Sorting");
Justify.display();


}

catch (Exception e) {
e.printStackTrace();
} finally {
stmt.close();
conn.close();
}

}
}


package com.nt.finals;

public class Employ {
private int id;
private String job;
private int salary;
Employ(){

}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getJob() {
return job;
}
public void setJob(String job) {
this.job = job;
}
public int getSalary() {
return salary;
}
public void setSalary(int salary) {
this.salary = salary;
}
@Override
public String toString() {
return "Employ [id=" + id + ", job=" + job + ", salary=" + salary + "]";
}

}

How to sort Database table(Many columns) using Comparable in collections:

we can sort the Database Table of multiple columns using the Comparable in the  Collection  concept.
package com.nt.extensive;

import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;

public class User {

public static void main(String[] args) throws IOException {

final String DB_URL = "jdbc:mysql://localhost:3307/organization";
    Scanner sc=new Scanner(System.in);
// Database credentials
final String USER = "root";
final String PASS = "root";

Connection conn = null;
Statement stmt = null;
try {
// STEP 2: Register JDBC driver
Class.forName("com.mysql.jdbc.Driver");

// STEP 3: Open a connection
System.out.println("Connecting to database");
conn = DriverManager.getConnection(DB_URL, USER, PASS);

if (conn != null)
// STEP 4: Execute a query
System.out.println("Creating statement...");
stmt = conn.createStatement();
String sql = null;
if (stmt != null)

sql = "SELECT ename,epassword,phonenumber,email,salary,Age FROM employee";

ResultSet rs = stmt.executeQuery(sql);
if (rs != null)
while (rs.next()) {
String sname = rs.getString("ename");
String password = rs.getString("epassword");
Long phonenumbers = rs.getLong("phonenumber");
String eemail = rs.getString("email");
Double Salary = rs.getDouble("salary");
int Age = rs.getInt("age");
System.out.print(sname);
System.out.print("\t");
System.out.print(Age);
System.out.print("\t");
System.out.print(password);
System.out.print("\t\t");
System.out.print(phonenumbers);
System.out.print("\t\t\t");
System.out.print(eemail);
System.out.print("\t\t\t");
System.out.print(Salary);
System.out.println();
}
ResultSetMetaData rsmd=rs.getMetaData();

int num=rsmd.getColumnCount();
System.out.println(num+" Columns");
for(int i=1;i<=num;i++)
{
System.out.println("Column Names        "+rsmd.getColumnName(i));
}
System.out.println("Enter 1. For Salary \t ");
System.out.println("Enter 2. For Ename \t ");
int i=sc.nextInt();

ResultSet rs1 = stmt.executeQuery("Select * from employee");
ArrayList<Newsort> al = new ArrayList<Newsort>();

while (rs1.next()) {

Newsort e = new Newsort();
String sname = (rs1.getString("ename"));
String password = (rs1.getString("epassword"));
Long phonenum = (rs1.getLong("phonenumber"));
String Email = (rs1.getString("Email"));
Double sal = (rs1.getDouble("salary"));
int age=(rs1.getInt("Age"));

e.setEname(sname);
e.setEpassword(password);
e.setPhonenumber(phonenum);
e.setEmail(Email);
e.setSalary(sal);
e.setAge(age);
                 e.setManipulate(i);
al.add(e);
               
}



for (Newsort em : al) {
System.out.println(em);
}

Collections.sort(al);
System.out.println("Sort Employees based on your Requirement ");


for (Newsort em : al) {
System.out.println(em);
}


}

catch (NullPointerException Ne) {
System.out.println("NullPointerException");
}

catch (ClassNotFoundException e) {
System.out.println("UnRegistered Driver");
} catch (SQLException sw) {
System.out.println("SqlException");
} finally {

try {
if (conn != null) {
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();

}
try {
if (stmt != null) {
stmt.close();
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

}



}

package com.nt.sense;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.math.BigDecimal;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Collections;

public class Restore {

static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
static final String DB_URL = "jdbc:mysql://localhost:3307/organization";

// Database credentials
static final String USER = "root";
static final String PASS = "root";

public static void main(String[] args) throws SQLException,
ClassNotFoundException {
Connection conn = null;
Statement stmt = null;
@SuppressWarnings("unused")
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

// STEP 2: Register JDBC driver
Class.forName("com.mysql.jdbc.Driver");

// STEP 3: Open a connection
System.out.println("Connecting to database");
conn = DriverManager.getConnection(DB_URL, USER, PASS);

// STEP 4: Execute a query
System.out.println("Creating statement...");
stmt = conn.createStatement();
String sql;
sql = "SELECT ename,epassword,phonenumber,email FROM employee";
ResultSet rs = stmt.executeQuery(sql);
while (rs.next()) {
String sname = rs.getString("ename");
String password = rs.getString("epassword");
BigDecimal phonenumbers = rs.getBigDecimal("phonenumber");
String eemail = rs.getString("email");
System.out.print(sname);
System.out.print("\t");
System.out.print(password);
System.out.print("\t");
System.out.print(phonenumbers);
System.out.print("\t");
System.out.print(eemail);
System.out.println();
}
System.out.println("this is the display of ename only");
String sql2;
sql2 = "SELECT epassword from employee";
ResultSet rs1 = stmt.executeQuery(sql2);
System.out.println("start.....");
ArrayList<String> al = new ArrayList<String>();
while (rs1.next()) {
{
al.add(rs1.getString("epassword"));
}

}

for (String s : al) {
System.out.println(s);
}

Collections.sort(al);
System.out.println("After sorting");
for (String s1 : al) {
System.out.println(s1);
}
}

}

package com.nt.files;

import java.awt.Image;
import java.io.FileInputStream;

import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;

public class UsingSwings {
public static void main(String[] args) {
FileInputStream fis=null;
try
{
fis=new FileInputStream("F://workspaces//testworkspace//Tasks//src//com//nt//files//bird.jpg");

Image img=ImageIO.read(fis);

JFrame jf=new JFrame();
jf.add(new JLabel(new ImageIcon(img)));
jf.pack();
jf.setVisible(true);
}
catch(Exception e)
{

}
}
}

package com.nt.files;

import java.io.BufferedReader;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;

public class DoQuick
{
private static FileOutputStream   fout;

public static void main(String[] args) throws IOException
{
String sr;
fout = new FileOutputStream("F://workspaces//testworkspace//Tasks//src//com//nt//files//learn.txt",true);
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
sr=br.readLine();
while(!sr.equalsIgnoreCase("Quit"))
{

byte[] b=sr.getBytes();
fout.write(b);
fout.write((char)'\n');
sr=br.readLine();
}



}
}

Difference between ArrayList and LinkedList

ArrayList and LinkedList both implements List interface and maintains insertion order. Both are non synchronized classes.

But there are many differences between ArrayList and LinkedList classes that are given below.

ArrayList                                                                                          
1) ArrayList internally uses dynamic array to store the elements.
2) Manipulation with ArrayList is slow because it internally uses array.      
3) ArrayList class can act as a list only because it implements List only.
4) ArrayList is better for storing and accessing data.
5>Array List search operation is quicker than Linked List bcoz it is Index based system.
6)Removal or deletion in Linked List is quicker than ArrayList.
7)When huge amount of elements we are using it is better to adopt ArrayList.
8)In Linked List it takes Memory consumption for storing the pointers.

LinkedList:

• LinkedList internally uses doubly linked list to store the elements.

• If any element is removed from the array, all the bits are shifted in memory. Manipulation with LinkedList is faster than ArrayList because it uses doubly linked list so no bit shifting is required in memory.

• LinkedList class can act as a list and queue both because it implements List and Deque interfaces.

When to Use:
a)ArrayList can be used for high acessing,Inserting and low manipulation.
b)LinkedList can be used for high manipulation and low accessing elements.


ABOUT STACK:

1)Stack follows the LIFO(Last in First Out)                                                                                            
2)peek,pop,push are the methods used in stack.
3)used for calculating postfix and prefix expressions.
4)

Map:

1)To get the elements we use entrySet()method.
2)In Map <k,v> type follows
3)we can set Map collection into anothercollection class easily by setting like
eg:set<Entry<key,value>> then it must take <k,v> in to a single value.
4)keySet()is used to display keys only.
5)For iteration HashMap must be as follows
Eg: for(Map.Entry entry:CollectionObject.entrySet()) to iterate.




HashMap:

1)It consists of <k,v> value pairs they must be stored.
2)hashMap is unSynchronized .
3)It allows only one null key and multiple null values.
4)Insertion order is not preserved up to java 1.7.

LinkedHashMap:

1)it implements Map Interface and extends HashMap Class.
2)Insertion order is maintained in LinkedHashMap.
3)Searching an element is quick in Linked Hashmap.

iteration in index order, allowing duplicates.
ArrayList should be used for random access get(i) or set(i,o) by index.
HashMap are good default choices when random access by element or keyis needed,and sequential access in element or key order is not needed.

Operation  LinkedList ArrayList HashMap   LinkedHashMap  TreeMap

Add(o)(last)  O(1)             O(1)a

Add(i,o)            O(d)        O(n-i)a

addFirst(o) O(1)

Put(k,v)                                                         O(1)a                    O(log n)

Remove(o) O(n)                                  O(n)            O(1)                   O(log n)

Remove(i) O(d)        O(n-i)

removeFirst() O(1)

Contains(o) O(n)         O(n)

ContainsKey(o)                                                   O(1)         O(log n)


ContainsValue(o)             O(n)           O(n)

indexOf(o) O(n)          O(n)

Get(i)       O(d)     O(1)


Set(i,o)       O(d) O(1)


Get(o)                                            O(1)         O(log n)







About this table tells the:

o(1): It is the constant time to complete the operation or task.



o(log n): Time Proportional to the logarthm of n means it takes to insert  2 elements in 1sec (or) 1 element in 2sec. the time taken directly propotional to the data set
          not so direct proprtional we dont tell how much it takes to do operation.



o(n): Suppose we take 2 elements it takes  2 sec for 100 elements it takes 100 seconds it depends on the dataset we are giving.



o(d): d is the distance from an index i to the nearest end of the list, that is min(i,n-i), for linked list adding and removing is fast bcoz their d is small.

       In ArrayList is fast for only the neat back end. where n-i is small.

o(1)a : Amortized Complexity means over a long sequence of operations the average time  it takes o(1), for single operation it could take o(n).

About Collections in Java:

Collections is a java class that can store and retrieve the elements where you stored.

Collections is obtained from java.util Package.

In Collections  the Structure how the Collection is framed given Below.

1.   List                                      2. Queue                                     3. Set                      
   
   1.1   Array List                        2.1  Priority Queue                 3.1 Hash Set    
   1.2  Linked List                               2.1.1  Deque                                     3.1.1 Linked HashSet
   1.3   Vector                                       2.1.2 Array Deque                      3.2 Sorted Set  
          1.3.1   Stack                        2.2  BlockingQueue                           3.2.1  NavigableSet      
                                                    2.2.1   Priority Blocking Queue                    3.2.2  TreeSet
                                                  2.2.2 Linked Blocking Queue                       .



                                                   4.  Map
                                     
 4.1  HashMap                       4.2  WeakedHashMap               4.3 SortedMap             4.4 Dictionary
  4.1.1   Linked Hash Map        4.2.1 Identity HashMap            4.3.1 NavigableMap  4.4.1   HashTable
                                                                                                      4.3.2 TreeMap           4.4.2  Properties

Karnataka state Government of  Examinations  Authority announced to invite Online application for the post of Staff Nurse.

Number of Posts: 1064

Job Location : Bangalore (Karnataka)

Starting Date to Apply through Online : 02/11/2015

Closing  Date to Apply through Online : 02/12/2015.

Last Date to Pay Fees :04/12/2015.

Job Details :

Post Name : Staff Nurse

Pay Scale : Rs. 176500-32000/-

Eligibility Criteria :

Educational Qualification :  Candidate must Posses the Qualified B.Sc./Diploma Nursing from a Govt recognized Institute also  possess a certificate in General Nursing Course of not to be less than 3 years and a certificate in Midwifery or Psychiatric Nursing course of not to be less than 6 months from a Govt recognized institute .Karnataka Nursing Council is Mandatory.

Nationality : Should be an Indian

Age Limit : 35 years

Age Relaxation :

For 2A,2B,3A&3B Category Candidates : 3 Years

For SC/ST Candidates : 5 Years

Application Fees : Candidates who belongs to General Merit and others  have to pay an amount of Rs. 500/- and who  belongs to SC/ST/Category-1 have to pay an amount of  Rs. 300/- through Specified Bank . Differently Abled candidates are exempted for paying fee.

How to Apply : Interested candidates may apply Online through  this website http://www.kea.kar.nic.in/ 


Important Links :

Detail Advertisement Link : http://kea.kar.nic.in/staffnurse/notification_staffnurse.pdf

Apply Online : https://cetonline.karnataka.gov.in/CETStaffnurse/%28S%28e5e4o543apeu3ztdsadv0gdq%29%29/Home.aspx

Uttar Pradesh Govt has been  released a notification for Subordinate Service Selection Commission (UPSSSC)  in Lucknow inviting the applications for the

Name of the Posts

1) Assistant Development Officer,

2)Industrial Co Supervisor, Assistant Sericulture Development Officer, District Prohibition and

3)Smajotthan Officer & Combined Lower Subordinate Services

Last Date to  Apply Online : 04 November 2015. (Extended to 11 November 2015).


No . of Posts : 296

Advt No. : 18-EXAM /2015

Job Location : Uttar Pradesh

About Jobs :

Post Name : Assistant Development Officer

No. of Vacancy : 23 Posts
Pay Scale : Rs.5200-20200/-
Grade Pay : Rs.2800/-

Post Name : Industrial Co Supervisor
No. of Vacancy : 42 Posts
Pay Scale : Rs.5200-20200/-
Grade Pay : Rs.2000/-

Post Name : Assistant Sericulture Development Officer
No. of Vacancy : 25 Posts
Pay Scale : Rs.5200-20200/-
Grade Pay : Rs.2800/-

Post Name : District Prohibition and Smajotthan Officer
No. of Vacancy : 10 Posts
Pay Scale : Rs.5200-20200/-
Grade Pay : Rs.2800/-

Eligibility Criteria :

Educational Qualification :

For Assistant Development Officer : Candidates Must Posses the  Bachelors degree from a University established by law in India or a qualification recognized by Government.

For Industrial Co Supervisor : Bachelor’s degree and training in cooperation with recognized institute.

For Assistant Sericulture Development Officer : B.Sc. (biology), in which a paper of entomology or M.Sc  (agriculture) qualification or equivalent recognized by the Government.

For  District Prohibition and Smajotthan Officer : Candidate must be Graduated from the University established by Law in India or a qualification recognized as equivalent by the Government.

Nationality : Indian

Age Limit : 18 to 40 Years (As on 01.07.2015)

Selection Process : Selection will be through Written Examination & Interview.

Application Fee :

For General : Rs. 185/-

Other Backward Class : Rs. 185/-

Scheduled Caste/ Scheduled Tribe(SC's/ST's) : Rs. 95/-

PWD Category : Rs. 25/-

Candidates should be submitted  their fee through State Bank  Challana  Only.

How to Apply : Interested Candidates may apply Online through UPSSSC website 

 Click here to apply : http://upsssc.gov.in 

Important Dates to Remember :

Starting Date For Submission Of Online Application : 14.10.2015
Last Date to apply through  Online Application (Part-I) : 06.11.2015
Last Date to submit  Online Application (Part-II) : 11.11.2015
Last  Date for receipt of Application Fee : 09.11.2015

Important Links :

Detail Advertisement Link :
http://upsssc.gov.in/OuterPages/View_Enclosure.aspx?ID=706&flag=H&FID=1107

Apply Online : http://upsssc.gov.in/AllNotifications.aspx

Important Notice : http://upsssc.gov.in/View_Notices.aspx?ID=news&N=90