First Java Program

Java first program clear explanation:

public class FirstProgram {

    public static void main(String arg[])

    {

     System.out.println("this is the java first program");

    }

} 

Explanation:

è public class FirstProgram{

public keyword is an access modifier, it mean other class can access this class.

Class is a keyword to declare the class name.

FirstProgram is a class name of this program.

{ open brace, it mean starting of the class scope.

àpublic static void main(String arg[]){

Static is a keyword. If we declare a method as static, no need to create object for that method. Here no need to create object to invoke main method. The main method is executed by JVM.

Void is return. It does not return any value.

Main is a method name. It represents startup of the program.

(String arg[])  is main method parameter, it stores the  values as String array format  arg[] is a variable, we can given other name whatever we want(a[],b[],ect..).

Example :

String a=arg[0];

String b=arg[1];

{ open brace for main method. 

System.out.println(“this is the first java program”);

System is a class in the java.lang package.

Out is a static member of the System class

Println is a method of the java.io.PrintStream

} close main method

} close class

Execution: 

Save the above program as  : FirstProgram.java

Compile:  javac FirstProgram.java

Execution:  java FirstProgram

Output:   this is the first java program

Explanation in screen shots :

 

Start new project in NetBeans

Start new project in NetBeans:

Here I posted about, screen shots of start new web application project in NetBeans

Pass the Values via Hyperlink

Pass the Values to next jsp page via Hyperlink:

We can pass the values from one jsp page to other jsp page using Hyperlink

In this process first we get values from database and set that value to hyperlink.

tid=rs.getString(“id”);

<a href="edit.jsp?id=<%out.print(tid);%>">Edit Details</a>

“Id” is database column name, that the id value is stored in “tid” variable.

It shows the value while passing to the next jsp page.

Here I done an application with simple programming, it is very easy to understand, especially for beginners.

Download Source code(5kb file)

   

Code:

Here I done actions registration from, display details, update details, delete details.

Registration form (reg_form.jsp)

<h3>Registration Form</h3>

<form action="registration.jsp"method="post"> 
<table>

<tr><td>Id Number :</td><td><input type="text" name="id" required/></td></tr> 
<tr><td>Name :</td><td><input type="text" name="name" required/></td></tr>         

<tr><td>Gender :</td><td>

<input type="radio" name="gender" value="male"    required/>Male

<input type="radio" name="gender" value="female" required/>Female</td></tr>

<tr><td>Birth Date :</td><td><input type="date" name="date"required/></td></tr>

<tr><td>Phone Number :</td><td><input type="tel" name="phno"

 pattern="[0-9]{10}"required /></td></tr>          

<tr><td>Father Name :</td><td><input type="text"name="fathern"required/>

</td></tr>

<tr><td>Address :</td><td><input type="text" name="add"

placeholder="city/town,area"required/></td></tr> 
<tr><td></td><td><input type="submit" value="Signup" name="Signup" /></td></tr>            

</table>        </form>

Registration JSP Servlet (registration.jsp)

<%

try{

String id,name,dob,gender,phno,fathername,add;

id=request.getParameter("id");

name=request.getParameter("name");

gender=request.getParameter("gender");

dob=request.getParameter("date");

phno=request.getParameter("phno");

fathername=request.getParameter("fathern");

add=request.getParameter("add");

Class.forName("com.mysql.jdbc.Driver");

Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/narendar","user","12345");

String q="insert into student  values('"+id+"','"+name+"','"+gender+"','"+dob+"','"+phno+"','"+fathername+"','"+add+"')";

Statement st=con.createStatement();

int i=st.executeUpdate(q);

if(i>0){

out.print("Registration Successful....");

request.getRequestDispatcher("details.jsp").include(request, response);

}

}

catch(Exception e){

out.println(e);

}

%>

Display Details in table (details.jsp)

<h2>User Details.

</h2>

<h3><a href="reg_form.jsp">Add New User</a></h3>

<%

try{

Class.forName("com.mysql.jdbc.Driver");

Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/narendar","user","12345");

String q="select * from student";

Statement stmt=con.createStatement();

ResultSet re=stmt.executeQuery(q);

String id,name,gen,dob,phno,fn,add;

%>

<style>

tr:hover{

background-color:  #ddec01;

}

</style>

<table border="1">

<thead>

<tr>

<th>Id Number</th>

<th>Name</th>

<th>Gender</th>

<th>Date Of Birth</th>

<th>Phone Number</th>

<th>Father Name</th>

<th>Address</th>

<th></th>

<th></th>

</tr>

</thead>

<%

while(re.next()){

id=re.getString("id");

name=re.getString("name");

gen=re.getString("gender");

dob=re.getString("birthdate");

phno=re.getString("phno");

fn=re.getString("fathername");

add=re.getString("address");

%>

<tbody>

<tr>

<td><%out.print(id);%></td>

<td><%out.print(name);%></td>

<td><%out.print(gen);%></td>

<td><%out.print(dob);%></td>

<td><%out.print(phno);%></td>

<td><%out.print(fn);%></td>

<td><%out.print(add);%></td>

<td><a href="delete.jsp?id=<%out.print(id);%>">Delete</a></td>

<td><a href="edit.jsp?id=<%out.print(id);%>">Edit Details</a></td>

</tr>

</tbody><%}%>

</table>

<%

}

catch(Exception e){

out.print(e);

}%>

Edit Details (edit.jsp)

<h3>Update User Details</h3>

<%

try{

String id=request.getParameter("id");

Class.forName("com.mysql.jdbc.Driver");

Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/narendar","user","12345");

String q="select * from student where id='"+id+"'";

Statement stmt=con.createStatement();

ResultSet re=stmt.executeQuery(q);

String sid=null,name=null,gen=null,dob=null,phno=null,fn=null,add=null;

while(re.next()){

sid=re.getString("id");

name=re.getString("name");

gen=re.getString("gender");

dob=re.getString("birthdate");

phno=re.getString("phno");

fn=re.getString("fathername");

add=re.getString("address");

}

%>

<form action="update.jsp"method="post">

<table>

<tr><td>Id Number :</td><td><input type="hidden" name="id" value="<%out.print(sid);%>"required/></td></tr>

<tr><td>Name :</td><td><input type="text" name="name" value="<%out.print(name);%>"required/></td></tr>          

<tr><td>Gender :</td><td><input type="radio" name="gender" value="male" required/>Male

<input type="radio" name="gender" value="female" required/>Female</td></tr>

<tr><td>Birth Date :</td><td><input type="date" name="date"value="<%out.print(dob);%>"required/></td></tr>

<tr><td>Phone Number :</td><td><input type="tel" name="phno"pattern="[0-9]{10}"value="<%out.print(phno);%>"required /></td></tr>          

<tr><td>Father Name :</td><td><input type="text" name="fathern"value="<%out.print(fn);%>"required/></td></tr>

<tr><td>Address :</td><td><input type="text" name="add"value="<%out.print(add);%>"/></td></tr>

<tr><td></td><td><input type="submit" value="Signup" name="Signup" /></td></tr>

</table>

</form>

<% 

}

catch(Exception e){

System.err.print(e);

}

%>

Update Details (update.jsp)

<%

try{

String id,name,dob,gender,phno,fathername,add;

id=request.getParameter("id");

name=request.getParameter("name");

gender=request.getParameter("gender");

dob=request.getParameter("date");

phno=request.getParameter("phno");

fathername=request.getParameter("fathern");

add=request.getParameter("add");

Class.forName("com.mysql.jdbc.Driver");

Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/narendar","user","12345");

String q="update student set name='"+name+"',gender='"+gender+"',birthdate='"+dob+"',phno='"+phno+"',fathername='"+fathername+"',address='"+add+"' where id='"+id+"'";

Statement st=con.createStatement();

int i=st.executeUpdate(q);

if(i>0){

out.print("User details updated successful....");

request.getRequestDispatcher("details.jsp").include(request, response);

}

}

catch(Exception e){

out.println(e);

}

%>

Delete Details (delete.jsp)

<%

try{

String id=request.getParameter("id");

Class.forName("com.mysql.jdbc.Driver");

Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/narendar","user","12345");

String q1="delete from student where id='"+id+"'";

Statement stmt1=con.createStatement();

int i=stmt1.executeUpdate(q1);

System.out.print("User Details Deleted Successful....");

request.getRequestDispatcher("details.jsp").include(request, response);

}

catch(Exception e){

System.err.print(e);

}                

%>