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1) 3 times wrong password
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package myastfolder;

import java.awt.event.*;
import javax.swing.*;


public class Q1 {

	public static int cnt=0;
	public static boolean flag=false;
public static void main(String[] args) {


    JFrame f=new JFrame("Button Example");
    final JTextField tf=new JTextField();
    tf.setBounds(50,50, 150,20);
    JButton b=new JButton("Click Here");
    b.setBounds(50,100,95,30);

    JLabel l1;
    l1=new JLabel("");
    l1.setBounds(50,60, 150,50);

    f.add(l1);
    f.setSize(300,300);
    f.setLayout(null);
    f.setVisible(true);
    b.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
	int p;


	//int cnt=0;
           	   cnt++;
        	   if(tf.getText().equals("11"))
        	   {
        	//	   break;
        		   flag=true;
        		   l1.setText("congoo correct pwd!!!");
        	   }
        	   else
        	   {
        		   l1.setText("oops wrong pwd!!!");
        	   }

           if(cnt==3 && flag==false)
           {
        	   System.exit(0);
           }
           tf.setText("");
        }
    });
    f.add(b);f.add(tf);
    f.setSize(400,400);
    f.setLayout(null);
    f.setVisible(true);
}
}
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2)  SQLInjection

new.html

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<form action='userCheck' method="post">
<input type='text' name='user' value=''/>
<input type='submit' value='Submit'/>
</form>
</body>
</html>


userCheck.java


import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class userCheck extends HttpServlet {
	private static final long serialVersionUID = 1L;
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {

            String user = request.getParameter("user");
            //out.println(user);
            Connection conn = null;
            String url = "jdbc:mysql://192.168.100.75:3307/";
            String dbName = "dac7";
            String driver = "com.mysql.jdbc.Driver";
            String userName = "dac7";
            String password = "welcome";
            try {
                Class.forName(driver).newInstance();
                conn = DriverManager.getConnection(url + dbName, userName, password);

                Statement st = conn.createStatement();
                String query = "SELECT * FROM  user1 where username='"+user+"'";
                out.println("Query : " + query);
                System.out.printf(query);
                ResultSet res = st.executeQuery(query);

                out.println("Results");
                while (res.next()) {
                    String s = res.getString("username");
                    out.println("\t\t" + s);
                }
                conn.close();

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

}
}