JAVA BY RAMAKRISHNA

Monday, 7 October 2013

Read File Using FileReader,BufferedReader

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class BufferedReaderExample {

public static void main(String[] args) {

BufferedReader br = null;

try {

String s;
br = new BufferedReader(new FileReader("d:/ram.txt"));

while ((s = br.readLine()) != null) {
System.out.println(s);
}

} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (br != null)br.close();
} catch (IOException ex) {
ex.printStackTrace();
}
}

}
}

Read File Using Java 1.7 Files Class

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Iterator;
import java.util.List;

//Files class is available from 1.7
public class FilesClassExample {

public static void main(String args[]){
Path path = Paths.get("d:/ram.txt");

try {
/*
//Read file to byte array
byte[] bytes = Files.readAllBytes(path);

String val=new String(bytes);
System.out.println(val);

*/

//Read file to String list
List<String> allLines = Files.readAllLines(path, StandardCharsets.UTF_8);

Iterator<String> i=allLines.iterator();
while(i.hasNext()) {
System.out.println(i.next());
}

} catch (IOException e) {
e.printStackTrace();
}
}
}

Read File Contents Using Scanner

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class UsingScanner {

public static void main(String[] args) throws FileNotFoundException {
Scanner s=new Scanner(new File("d:/ram.txt"));
while (s.hasNextLine()) {
String line = s.nextLine();
System.out.println(line);
}
s.close();
}

}

Thursday, 3 October 2013

JQuery+Ajax+Json+Servlet+Maven Example

Explanation:

When we click the button , request will come to JQuery $.ajax method,and then execuete ServletClass ,ServletClass returns Json data as output,this output will display inside div.

Here JSONObject json = new JSONObject(); is used to create JSON data.

Maven pom.xml

</dependency>

</dependencies>

Welcome.html

<html>

<head>

$(document).ready(function() {

$("#SubmitButton").click(function() {

$.ajax({

url:'sc',

type:'GET',

dataType: 'json',

success: function(data) {

$("#main").html("<p>Name:"+data.name+",Company:"+data.company+"</p>");

error: function(e) {

alert(e.status);

}

});

</script>

</head>

<body>

<button id="SubmitButton">CallServlet</button>

</div>

</body>

</html>

ServletClass.java

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import org.json.JSONException;

import org.json.JSONObject;

public class ServletClass extends HttpServlet {

@Override

public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException {

PrintWriter out=response.getWriter();

JSONObject json = new JSONObject();

try {

json.put("name","java");

json.put("company","oracle");

} catch (JSONException e) {

e.printStackTrace();

}

out.print(json);

}

Web.xml

<web-app>

<servlet-name>sc</servlet-name>

<servlet-class>ServletClass</servlet-class>

<load-on-startup>2</load-on-startup>

</servlet>

<servlet-mapping>

<servlet-name>sc</servlet-name>

<url-pattern>/sc</url-pattern>

</servlet-mapping>

</web-app>

Saturday, 28 September 2013

Friday, 27 September 2013

JDBC CURD Operations using PreparedStatement

//Insert Record into table using PreparesStatement in JDBC

package com.iton;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class MainApp2 {

public static void main(String[] args) {

try {
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/ramakrishna","root","root");

String query="insert into emp values(?,?)";
PreparedStatement pstmt=con.prepareStatement(query);

pstmt.setInt(1,25);
pstmt.setString(2,"jamesGosling");
pstmt.executeUpdate();

System.out.println("+++Record inserted successfully+++");

} catch (SQLException e) {
e.printStackTrace();
}
}
}

//Update Record/Records in the table using PreparesStatement in JDBC

package com.iton;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class MainApp2 {

public static void main(String[] args) {

try {
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/ramakrishna","root","root");

String query="update emp set name=? where no=?";
PreparedStatement pstmt=con.prepareStatement(query);

pstmt.setString(1,"java");
pstmt.setInt(2,25);

pstmt.executeUpdate();

System.out.println("+++Record updated successfully+++");

} catch (SQLException e) {
e.printStackTrace();
}
}
}

//Delete Record/Records in the table using PreparesStatement in JDBC

package com.iton;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class MainApp2 {

public static void main(String[] args) {

try {
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/ramakrishna","root","root");

String query="delete from emp where no=?";
PreparedStatement pstmt=con.prepareStatement(query);

pstmt.setInt(1,25);

int count=pstmt.executeUpdate();

System.out.println("+++"+count+" Records deleted successfully+++");

} catch (SQLException e) {
e.printStackTrace();
}
}
}

//Retrieve Record/Records in the table using PreparesStatement in JDBC

package com.iton;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class MainApp2 {

public static void main(String[] args) {

try {
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/ramakrishna","root","root");

String query="select * from emp where no=?";
PreparedStatement pstmt=con.prepareStatement(query);

pstmt.setInt(1,26);

ResultSet rs=pstmt.executeQuery();

while(rs.next()) {
System.out.print("No:"+rs.getInt("no"));
System.out.println(" Name:"+rs.getString("name"));
}

} catch (SQLException e) {
e.printStackTrace();
}
}
}

JDBC CURD operations using Statement object

//Create table using Statement object in JDBC

package com.iton;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;

public class MainApp {

public static void main(String[] args) {

try {
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/ramakrishna","root","root");

Statement stmt = con.createStatement();
String query = "create table emp(no int,name varchar(15))";

stmt.executeUpdate(query);
System.out.println("+++Table is created successfully+++");

} catch (SQLException e) {
e.printStackTrace();
}
}
}

//Insert Record into table using Statement object in JDBC

package com.iton;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;

public class MainApp {

public static void main(String[] args) {

try {
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/ramakrishna","root","root");

Statement stmt = con.createStatement();
String query = "insert into emp values(25,'jamesGosling')";

stmt.executeUpdate(query);
System.out.println("+++Record inserted successfully+++");

} catch (SQLException e) {
e.printStackTrace();
}
}
}

//Update Record/Records in the table using Statement object in JDBC

package com.iton;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;

public class MainApp {

public static void main(String[] args) {

try {
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/ramakrishna","root","root");

Statement stmt = con.createStatement();
String query = "update emp set name='james' where no=25";

stmt.executeUpdate(query);
System.out.println("+++Record updated successfully+++");

} catch (SQLException e) {
e.printStackTrace();
}
}
}

//Delete Record/Records in the table using Statement object in JDBC

package com.iton;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;

public class MainApp {

public static void main(String[] args) {

try {
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/ramakrishna","root","root");

Statement stmt = con.createStatement();
String query = "delete from emp where no=25";

int count=stmt.executeUpdate(query);
System.out.println("+++"+count+" Records deleted successfully+++");

} catch (SQLException e) {
e.printStackTrace();
}
}
}

//Retrieve Record/Records in the table using Statement object in JDBC

package com.iton;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class MainApp {

public static void main(String[] args) {

try {
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/ramakrishna","root","root");

Statement stmt = con.createStatement();
String query = "select * from emp";

ResultSet rs=stmt.executeQuery(query);

while(rs.next()) {
System.out.print("No:"+rs.getInt("no"));
System.out.println(" Name:"+rs.getString("name"));
}

} catch (SQLException e) {
e.printStackTrace();
}
}
}