Mini Calculator in Java Swing

import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
class jframe extends JFrame implements ActionListener
{
String a=null,b=null,c=null;
double x,y,z;
JButton b1,b2,b3,b4;
JTextField t1,t2,t3;
Container con;
jframe(String s)
{
super(s);
setSize(300,300);
con=getContentPane();
con.setLayout(new FlowLayout(FlowLayout.LEFT));
t1=new JTextField(7);
t2=new JTextField(7);
t3=new JTextField(7);
b1=new JButton("+");
b2=new JButton("-");
b3=new JButton("X");
b4=new JButton("%");
b1.addActionListener(this);
b2.addActionListener(this);
b3.addActionListener(this);
b4.addActionListener(this);
con.add(t1);
con.add(t2);
con.add(t3);
con.add(b1);
con.add(b2);
con.add(b3);
con.add(b4);
addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
});

}
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==b1)
{

a=t1.getText();
b=t2.getText();
x=Double.parseDouble(a);
y=Double.parseDouble(b);
z=x+y;
t3.setText(String.valueOf(z));
}
if(e.getSource()==b2)
{

a=t1.getText();
b=t2.getText();
x=Double.parseDouble(a);
y=Double.parseDouble(b);
z=x-y;
t3.setText(String.valueOf(z));
}

if(e.getSource()==b3)
{
a=t1.getText();
b=t2.getText();
x=Double.parseDouble(a);
y=Double.parseDouble(b);
z=x*y;
t3.setText(String.valueOf(z));
}

if(e.getSource()==b4)
{
a=t1.getText();
b=t2.getText();
x=Double.parseDouble(a);
y=Double.parseDouble(b);
z=x/y;
t3.setText(String.valueOf(z));
}

}
}

class jframe1
{
public static void main(String args[])
{
JFrame f=new jframe("Frame with button");
f.setVisible(true);
}
}

JDBC Program to Show Data in Database

import java.io.*;
import java.sql.*;
import java.sql.Statement.*;
import java.sql.ResultSet.*;
class show
{
public static void main(String args[])
{
String n,c;
Connection cn;
Statement st;
ResultSet rs;
try
{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
cn=DriverManager.getConnection("jdbc:odbc:ucer","","");
st=cn.createStatement();
rs=st.executeQuery("select * from school");
while(rs.next())
{
n=rs.getString(1);
c=rs.getString(2);
System.out.println("name "+n+" city "+c);
}

}
catch(Exception xx)
{
System.out.println("check data"+xx.getMessage());
}
}
}

JDBC Program to Save Data in Database

import java.io.*;
import java.sql.*;
import java.sql.Connection.*;
import java.sql.PreparedStatement.*;
class save
{
        public static void main(String args[])
        {
                String n,c;
                Connection cn;
                PreparedStatement pst;
int x;
                try
                {
InputStreamReader ir=new InputStreamReader(System.in);
BufferedReader br=new BufferedReader(ir);
System.out.println("enter name & city");
n=br.readLine();
c=br.readLine();


Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");

cn=DriverManager.getConnection("jdbc:odbc:ucer","","");

pst=cn.prepareStatement("insert into school(name,city) values(?,?)");
pst.setString(1,n);
pst.setString(2,c);
x=pst.executeUpdate();
if(x==1)
{
System.out.println("Record has been saved");
}

                }
                catch(Exception xx)
{
System.out.println("please check the data "+xx.getMessage());
}
        }
}

JDBC Program to Delete Data in Database

import java.io.*;
import java.sql.*;
class del
{
public static void main(String args[])
{
String n;
int x;
Connection k;
PreparedStatement pp;
try
{
n=args[0];
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
k=DriverManager.getConnection("jdbc:odbc:ucer","","");
pp=k.prepareStatement("delete from school where name=?");
pp.setString(1,n);
x=pp.executeUpdate();
if(x==1)
{
System.out.println("record has been deleted");
}

}
catch(Exception xx)
{
System.out.println("check data"+xx.getMessage());
}
}
}

Applet Program to Display Multiple Images in java

import java.applet.*;
import java.awt.*;
import java.net.*;
public class app extends Applet
{
String m1,m2,m3,m4;
URL codb;
Image picture;
public void init()
{
codb=getCodeBase();
picture=getImage(codb,"a.jpg");
setForeground(Color.green);
setBackground(Color.red);
m1="init";
}
public void start()
{
m2="start";
}

public void stop()
{
m3="stop";
}

public void destroy()
{
m4="destroy";
}

public void paint(Graphics g)
{
g.drawImage(picture,10,10,this);
g.drawString(m1,20,30);
g.drawString(m2,20,40);
g.drawString(m3,20,50);
g.drawString(m4,20,60);
g.drawString("hello",20,70);
g.drawRect(0,0,100,100);
resize(200,300);
}

}
/*
<applet code=app width=400 height=400></applet>
*/ 

Multithreading Program in Java

class merathread implements Runnable
{
int i,sum=0;
Thread th;
merathread()
{
th=new Thread(this,"My thread 2");
System.out.println("Thread name is"+th.getName());
th.start();

}
public void run()
{
System.out.println("Thread name is"+th.getName());
for(int i=0;i<10;i++)
{
Thread.sleep(2000);
}

}
}

Key Event in Applet using Java

import java.awt.*;
import java.applet.*;
import java.awt.event.*;
public class Keyeventdemo extends Applet implements KeyListener
{
String msg;
public void init()
{
addKeyListener(this);
}
public void keyPressed(KeyEvent k)
{
showStatus("Key Pressed");
}

public void keyReleased(KeyEvent k)
{
showStatus("Key Released");
}

public void keyTyped(KeyEvent k)
{
msg=msg+k.getKeyChar();
repaint();
}
public void paint(Graphics g)
{
g.drawString(msg,20,40);
}
}
/*
<applet code=Keyeventdemo width=300 height=300>
</applet>
*/