Variable Scope:
public class VarScopeProg
{
public static void main(String[] args)
{
int A=10;
{
int B=20;
System.out.println("Block A: "+A);
System.out.println("Block B: "+B);
}//scope of B=20 ends here
{
int B=30;//scope of B=30 starts here
System.out.println("Block A: "+A);
System.out.println("Block B: "+B);
}//scope of B=30 ends here
int B=40;//scope of B=40 starts here
{
System.out.println("Block A: "+A);
System.out.println("Block B: "+B);
}
}//scope of all the variables end here
}
Use Of Class:
/*This is a Java program which shows theuse of class in the program
*/
class Rectangle
{
int height;
int width;
void area()
{
int result=height*width;
System.out.println(“The area is ”+result);
}
}
class classDemo
{
public static void main(String args[])
{
Rectangle obj=new Rectangle();
obj.height=10;//setting the attribute values
obj.width=20;//from outside of class
obj.area();//using object method of class is called
}
}
Type Casting
public class TypeCastProg
{
public static void main(String[] args)
{
double x;
int y;
x=25.50;
System.out.println("Value of [double] x: "+x);
System.out.println("Conversion of double to integer");
y=(int)x;
System.out.println("Value of [integer] y: "+y);
int m;
double n;
m=10;
n=(double)m;
System.out.println("Value of [integer] m: "+m);
System.out.println("Conversion of integer to double");
System.out.println("Value of [double] n: "+n);
}
}
Exception Handling
class ExceptionDemo
{
public static void main(String args[])
{
try
{
int a,b;
a=5;
b=a/0;
}
catch(ArithmeticException e)
{
System.out.println("Divide by Zero\n");
}
System.out.println("...Executed catch statement");
}
}
<%@ page language="java" import="java.sql.*" %>
<%@ page import="java.io.*" %>
<%
Connection conn=null;
ResultSet rs=null;
Statement stmt=null;
Class.forName("com.mysql.jdbc.Driver").newInstance();
conn=
DriverManager.getConnection("jdbc:mysql://localhost:3306/students","root","system");
out.write("Connected to mysql!!!");
stmt=conn.createStatement();
if(request.getParameter("action") != null)
{
String Studname=request.getParameter("Studname");
String Studaddress=request.getParameter("Studaddress");
String Studphone=request.getParameter("Studphone");
stmt.executeUpdate("insert into students_table(name,address,phone) values
(' "+Studname+" ',' "+Studaddress+" ',' "+Studphone+" ')" );
rs=stmt.executeQuery("select * from students_table");
%>
<html>
<body>
<center>
<h2>Student List</h2>
<table border="1" cellspacing="0" cellpadding="0">
<tr>
<td><b>Roll No</b></td>
<td><b>Student Name</b></td>
<td><b>Address</.b></td>
<td><b>Phone</.b></td>
</tr>
<%
int num=1;
while(rs.next()){
%>
<tr>
<td><%=num%></td>
<td><%=rs.getString("name")%></td>
<td> <%=rs.getString("address")%></td>
<td> <%=rs.getString("phone")%></td>
</tr>
<%
num++;
}
rs.close();
stmt.close();
conn.close();
%>
</table>
</center>
</body>
</html>
<%}else{%>
<html>
<head>
<title>Student Registartion Demo</title>
<script language="javascript">
function validation(Form_obj)
{
if(Form_obj.Studname.value.length==0){
alert("Please,fill up the remaining information!!");
Form_obj.Studname.focus();
return false;
}
if(Form_obj.Studaddress.value.length==0){
alert("Please,fill up the remaining information!!");
Form_obj.Studaddress.focus();
return false;
}
if(Form_obj.Studphone.value.length==0){
alert("Please,fill up the remaining information!!");
Form_obj.Studphone.focus();
return false;
}
return true;
}
</script>
</head>
<body>
<center>
<form action="StudentForm.jsp" method="post"
name="entry" onSubmit="return validation(this)">
<input type="hidden" value="list" name="action">
<table border="3" cellpadding="0" cellspacing="0">
<tr>
<td>
<table>
<tr>
<td colspan="2" align="center">
<h2>Student Entry Form</h2></td>
</tr>
<tr>
<td colspan="2"> </td>
</tr>
<tr>
<td>Student Name:</td>
<td><input name="Studname" type= "text" size="50"></td>
</tr>
<tr>
<td>Address:</td>
<td><input name="Studaddress" type="text" size="50"></td>
</tr>
<td>Phone:</td>
<td><input name="Studphone" type="text" size="15"></td>
</tr>
<tr>
<td colspan="2" align="center">
<input type="submit" value="Submit"></td>
</tr>
</table>
</td>
</tr>
</table>
</form>
</center>
</body>
</html>
<%}%>
class Thread_demo implements Runnable
{
String str,msg;
Thread t;
Thread_demo(String str)
{
msg=str;
t=new Thread(this,str);
t.start();//directs to the run method
}
public void run()//thread execution starts
{
for(int i=1;i<=5;i++)
{
System.out.println(msg);
}
try
{
Thread.sleep(1000);
}
catch(InterruptedException e)
{
System.out.println("Exception in Thread handling");
}
}
}
public class Many_Thread_runnable
{
public static void main(String args[])
{
Thread_demo t1=new Thread_demo("First Thread");
Thread_demo t2=new Thread_demo("Second Thread");
Thread_demo t3=new Thread_demo("Third Thread");
}
}
/******************************************************
This is a Java program which creates a three thread
by extending the Thread class
*******************************************************/
class Thread_demo extends Thread
{
String msg;
Thread_demo(String str)
{
msg=str;
start();//directs to the run method
}
public void run()//thread execution starts
{
for(int i=1;i<=5;i++)
{
System.out.println(msg);
}
try
{
Thread.sleep(1000);
}
catch(InterruptedException e)
{
System.out.println("Exception in Thread handling");
}
}
}
public class Many_Thread
{
public static void main(String args[])
{
Thread_demo t1=new Thread_demo("First Thread");
Thread_demo t2=new Thread_demo("Second Thread");
Thread_demo t3=new Thread_demo("Third Thread");
}
}
import java.awt.*;
import java.applet.*;
/*
<applet code="MethodDemo" width=350 height=200>
</applet>
*/
public class MethodDemo extends Applet
{
String msg;
public void init()
{
msg="init method: ";
}
public void start()
{
msg=msg+"start method: ";
}
public void stop()
{
msg=msg+"stop method: ";
}
public void destroy()
{
msg=msg+"destroy method: ";
}
public void paint(Graphics g)
{
msg=msg+"paint method: ";
g.drawString(msg,50,30);
}
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public class LifeCycle extends GenericServlet
{
public void init(ServletConfig config) throws ServletException
{
System.out.println("init");
}
public void service(ServletRequest request, ServletResponse response)
throws ServletException, IOException
{
System.out.println("from service");
PrintWriter out = response.getWriter();
out.println("Twinkle Twinkle Little Stars.");
out.print("How I wonder what you are.");
}
public void destroy()
{
System.out.println("destroy");
}
}
Sample Student form using jsp
Sample Student form using jsp
<%@ page language="java" import="java.sql.*" %>
<%@ page import="java.io.*" %>
<%
Connection conn=null;
ResultSet rs=null;
Statement stmt=null;
Class.forName("com.mysql.jdbc.Driver").newInstance();
conn=
DriverManager.getConnection("jdbc:mysql://localhost:3306/students","root","system");
out.write("Connected to mysql!!!");
stmt=conn.createStatement();
if(request.getParameter("action") != null)
{
String Studname=request.getParameter("Studname");
String Studaddress=request.getParameter("Studaddress");
String Studphone=request.getParameter("Studphone");
stmt.executeUpdate("insert into students_table(name,address,phone) values
(' "+Studname+" ',' "+Studaddress+" ',' "+Studphone+" ')" );
rs=stmt.executeQuery("select * from students_table");
%>
<html>
<body>
<center>
<h2>Student List</h2>
<table border="1" cellspacing="0" cellpadding="0">
<tr>
<td><b>Roll No</b></td>
<td><b>Student Name</b></td>
<td><b>Address</.b></td>
<td><b>Phone</.b></td>
</tr>
<%
int num=1;
while(rs.next()){
%>
<tr>
<td><%=num%></td>
<td><%=rs.getString("name")%></td>
<td> <%=rs.getString("address")%></td>
<td> <%=rs.getString("phone")%></td>
</tr>
<%
num++;
}
rs.close();
stmt.close();
conn.close();
%>
</table>
</center>
</body>
</html>
<%}else{%>
<html>
<head>
<title>Student Registartion Demo</title>
<script language="javascript">
function validation(Form_obj)
{
if(Form_obj.Studname.value.length==0){
alert("Please,fill up the remaining information!!");
Form_obj.Studname.focus();
return false;
}
if(Form_obj.Studaddress.value.length==0){
alert("Please,fill up the remaining information!!");
Form_obj.Studaddress.focus();
return false;
}
if(Form_obj.Studphone.value.length==0){
alert("Please,fill up the remaining information!!");
Form_obj.Studphone.focus();
return false;
}
return true;
}
</script>
</head>
<body>
<center>
<form action="StudentForm.jsp" method="post"
name="entry" onSubmit="return validation(this)">
<input type="hidden" value="list" name="action">
<table border="3" cellpadding="0" cellspacing="0">
<tr>
<td>
<table>
<tr>
<td colspan="2" align="center">
<h2>Student Entry Form</h2></td>
</tr>
<tr>
<td colspan="2"> </td>
</tr>
<tr>
<td>Student Name:</td>
<td><input name="Studname" type= "text" size="50"></td>
</tr>
<tr>
<td>Address:</td>
<td><input name="Studaddress" type="text" size="50"></td>
</tr>
<td>Phone:</td>
<td><input name="Studphone" type="text" size="15"></td>
</tr>
<tr>
<td colspan="2" align="center">
<input type="submit" value="Submit"></td>
</tr>
</table>
</td>
</tr>
</table>
</form>
</center>
</body>
</html>
<%}%>
Creating a thread by using Runnable Interface
Creating a thread by using Runnable Interface
class Thread_demo implements Runnable
{
String str,msg;
Thread t;
Thread_demo(String str)
{
msg=str;
t=new Thread(this,str);
t.start();//directs to the run method
}
public void run()//thread execution starts
{
for(int i=1;i<=5;i++)
{
System.out.println(msg);
}
try
{
Thread.sleep(1000);
}
catch(InterruptedException e)
{
System.out.println("Exception in Thread handling");
}
}
}
public class Many_Thread_runnable
{
public static void main(String args[])
{
Thread_demo t1=new Thread_demo("First Thread");
Thread_demo t2=new Thread_demo("Second Thread");
Thread_demo t3=new Thread_demo("Third Thread");
}
}
creating a three thread by extending the Thread class
creating a three thread by extending the Thread class
/******************************************************
This is a Java program which creates a three thread
by extending the Thread class
*******************************************************/
class Thread_demo extends Thread
{
String msg;
Thread_demo(String str)
{
msg=str;
start();//directs to the run method
}
public void run()//thread execution starts
{
for(int i=1;i<=5;i++)
{
System.out.println(msg);
}
try
{
Thread.sleep(1000);
}
catch(InterruptedException e)
{
System.out.println("Exception in Thread handling");
}
}
}
public class Many_Thread
{
public static void main(String args[])
{
Thread_demo t1=new Thread_demo("First Thread");
Thread_demo t2=new Thread_demo("Second Thread");
Thread_demo t3=new Thread_demo("Third Thread");
}
}
Applet Program in java
Applet Program in java
import java.awt.*;
import java.applet.*;
/*
<applet code="MethodDemo" width=350 height=200>
</applet>
*/
public class MethodDemo extends Applet
{
String msg;
public void init()
{
msg="init method: ";
}
public void start()
{
msg=msg+"start method: ";
}
public void stop()
{
msg=msg+"stop method: ";
}
public void destroy()
{
msg=msg+"destroy method: ";
}
public void paint(Graphics g)
{
msg=msg+"paint method: ";
g.drawString(msg,50,30);
}
Servlet Life Cycle
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public class LifeCycle extends GenericServlet
{
public void init(ServletConfig config) throws ServletException
{
System.out.println("init");
}
public void service(ServletRequest request, ServletResponse response)
throws ServletException, IOException
{
System.out.println("from service");
PrintWriter out = response.getWriter();
out.println("Twinkle Twinkle Little Stars.");
out.print("How I wonder what you are.");
}
public void destroy()
{
System.out.println("destroy");
}
}
No comments:
Post a Comment