Java 8 Interview question with solution

 Example:1 / Filter employees with salary > 50000 and get their names(map example)

Solution:

Output:

High Earning Employees: [Alice, Charlie]   

Program:

import java.util.*;

import java.util.stream.Collectors;

class Employee {

    String name;

    double salary;

    Employee(String name, double salary) {

        this.name = name;

        this.salary = salary;

    }

}

public class EmployeeMapExample {

    public static void main(String[] args) {

        List<Employee> employees = Arrays.asList(

                new Employee("Alice", 60000),

                new Employee("Bob", 45000),

                new Employee("Charlie", 70000)

        );

        // Filter employees with salary > 50000 and get their names

        List<String> highEarnerNames = employees.stream()

                .filter(emp -> emp.salary > 50000) // condition

                .map(emp -> emp.name)             // transform Employee to name

                .collect(Collectors.toList());    // collect as List<String>

        System.out.println("High Earning Employees: " + highEarnerNames);

    }

}

GitLab - Package registry & mvn command to deploy the package

 Token Name/Username: Test    

  The role should be:Developer

Project id:59093775

.gitlab-ci.yml

# This file is a template, and might need editing before it works on your project.
# To contribute improvements to CI/CD templates, please follow the Development guide at:
# https://docs.gitlab.com/ee/development/cicd/templates.html
# This specific template is located at:
# https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/gitlab/ci/templates/Maven.gitlab-ci.yml

# Build JAVA applications using Apache Maven (http://maven.apache.org)
# For docker image tags see https://hub.docker.com/_/maven/
#
# For general lifecycle information see https://maven.apache.org/guides/introduction/introduction-to-the-lifecycle.html

# This template will build and test your projects
# * Caches downloaded dependencies and plugins between invocation.
# * Verify but don't deploy merge requests.
# * Deploy built artifacts from master branch only.
#before_script:
image: maven:3.8.4-openjdk-17



variables:
  workload_name: core
  core_project: com
  # `showDateTime` will show the passed time in milliseconds. You need to specify 

`--batch-mode` to make this work.
#  MAVEN_OPTS: >-
#    -Dhttps.protocols=TLSv1.2
#    -Dmaven.repo.local=$CI_PROJECT_DIR/.m2/repository
#    -Dorg.slf4j.simpleLogger.showDateTime=true
#    -Djava.awt.headless=true

  # As of Maven 3.3.0 instead of this you MAY define these options in `.mvn/maven.config` so the same config is used
  # when running from the command line.
  # As of Maven 3.6.1, the use of `--no-tranfer-progress` (or `-ntp`) suppresses download and upload messages. The use
  # of the `Slf4jMavenTransferListener` is no longer necessary.
  # `installAtEnd` and `deployAtEnd` are only effective with recent version of the corresponding plugins.
#  MAVEN_CLI_OPTS: >-
#    --batch-mode
#    --errors
#    --fail-at-end
#    --show-version
#    --no-transfer-progress
#    -DinstallAtEnd=true
#    -DdeployAtEnd=true

# This template uses the latest Maven 3 release, e.g., 3.8.6, and OpenJDK 8 (LTS)
# for verifying and deploying images
# Maven 3.8.x REQUIRES HTTPS repositories.
# See https://maven.apache.org/docs/3.8.1/release-notes.html#how-to-fix-when-i-get-a-http-

repository-blocked for more.

stages:
#  - test
  - build
  - package
#  - upload
#  - release
  - deploy

# Cache downloaded dependencies and plugins between builds.
# To keep cache across branches add 'key: "$CI_JOB_NAME"'
# Be aware that `mvn deploy` will install the built jar into this repository. If you notice

 your cache size
# increasing, consider addin g `-Dmaven.install.skip=true` to `MAVEN_OPTS` or in `.mvn/maven.config`
#cache:
#  paths:
#    - /.m2/repository

# For merge requests do not `deploy` but only run `verify`.
# See https://maven.apache.org/guides/introduction/introduction-to-the-lifecycle.html
#.verify:
#  stage: test
#  script:
#    - 'mvn $MAVEN_CLI_OPTS verify'
#  except:
#    variables:
#      - $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH
#
## Verify merge requests using JDK8
#verify:jdk8:
#  extends:
#    - .verify

# To deploy packages from CI, create a `ci_settings.xml` file
# For deploying packages to GitLab's Maven Repository: See https://docs.gitlab.com/ee/user/

packages/maven_repository/index.html#create-maven-packages-with-gitlab-cicd for more details.
# Please note: The GitLab Maven Repository is currently only available in GitLab Premium / Ultimate.
# For `master` or `main` branch run `mvn deploy` automatically.
#deploy:jdk8:
#  stage: deploy
#  script:
#    - if [ ! -f ci_settings.xml ]; then
#        echo "CI settings missing\! If deploying to GitLab Maven Repository, please see 

https://docs.gitlab.com/ee/user/packages/maven_repository/index.html#create-maven-packages-

with-gitlab-cicd for instructions.";
#      fi
#    - 'mvn $MAVEN_CLI_OPTS deploy --settings ci_settings.xml'
#  only:
#    variables:
#      - $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH
build-app:
  stage: build
#  tags:
#    - docker
  script:
    - echo "Maven compile started"
    - "mvn install"
  artifacts:
    paths:
      - target/core-0.0.1-SNAPSHOT.jar
#      - https://gitlab.com/monikasahu200595/microservices/59093775/packages/maven/core-0.0

.1-SNAPSHOT.jar

package-snapshot:
  stage: package
  #  tags:
  #    - docker
  script:
    - echo "Jar package started"
    - "mvn package"

#deploy-snapshot:
#  stage: deploy
#  #  tags:
#  #    - docker
#  script:
#    - echo "Jar deploy started"
#    - "mvn deploy"

#upload:
#  stage: upload
##  before_script:
##    - export VERSION=$(grep -m1 '<version>' pom.xml | grep -oP  '(?<=>).*(?=<)')
#  script:
#    - echo $VERSION
##    - 'curl --header "JOB-TOKEN: $CI_JOB_TOKEN" --upload-file target/file_name.jar 

"${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/packages/generic/package-name/$VERSION-${CI_COMMIT_SHORT_SHA}/file_name.jar"'
#    - 'curl --header "JOB-TOKEN: $CI_JOB_TO

KEN" --upload-file target/core-0.0.1-SNAPSHOT.jar "https://gitlab.com/monikasahu200595/

microservices/59093775/packages/maven/core-0.0.1-SNAPSHOT.jar"'
#  dependencies:
#    - build-app

deploy:
  stage: deploy
  script:
    - "mvn deploy"
# Configure Maven settings for deployment
# Create a settings.xml file for Maven with GitLab CI/CD environment variables

Where to get Project Name  and Project ID:

Check if you have project access by access token:

Command to deploy image into package registry:

mvn settings.xml deploy -DgeneratePom=true -DaltDeploymentRepository=gitlab-maven::default::https://gitlab.com/api/v4/projects/59093775/packages/maven

ArrayList And 2D ArrayList Iteartions

 package scaler.ifElse2.Arraylist;

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

public class ArrayListExample {
    public static void main(String[] args) {
        ArrayList<ArrayList<Integer>> A = new ArrayList<ArrayList<Integer>>();
        ArrayList<Integer> A1 = new ArrayList<Integer>();
        A1.add(1);
        A1.add(2);
        A1.add(3);
        List<Integer> A1Stream=A1.stream().collect(Collectors.toList());
        System.out.println("A 1 Stream loop :"+A1Stream);
        ArrayList<Integer> A2 = new ArrayList<Integer>();
        A2.add(11);
        A2.add(22);
        A2.add(33);
        for(int i=0;i<A2.size();i++){
            System.out.println("A2 iterate by simple for loop :"+A2.get(i));
        }
        ArrayList<Integer> A3 = new ArrayList<Integer>();
        A3.add(111);
        A3.add(222);
        A3.add(333);
        for(int a3 : A3){
            System.out.println("A3 iterate by for each :"+a3);
        }
        System.out.println(A1);
        System.out.println(A2);
        System.out.println(A3);
        A.add(A1);
        A.add(A2);
        A.add(A3);
        System.out.println("A :"+A);
        System.out.println(A.get(0).get(0));

       List<ArrayList<Integer>> j=A.stream().collect(Collectors.toList());
        System.out.println(j);

       A.stream().forEach(a -> System.out.println("For each stream : "+a));


       //first way to iterate by for Each
        for(ArrayList<Integer> aa:A){
            System.out.println("aa :"+aa);
            for(Integer aaa:aa){
                System.out.println("aaa :"+aaa);
            }
        }

        for(int i=0;i<A.size();i++){
            for(int m=0;m<A.get(i).size();m++){
                System.out.println("aaa   111111111111111 :"+A.get(i).get(m));
            }
        }

    }

}

OutPut:

"C:\Program Files\Java\jdk1.8.0_311\bin\java.exe" -javaagent:C:\Users\monik\AppData\Local\JetBrains\Toolbox\apps\IDEA-C\ch-0\213.5744.223\lib\idea_rt.jar=64922:C:\Users\monik\AppData\Local\JetBrains\Toolbox\apps\IDEA-C\ch-0\213.5744.223\bin -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_311\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_311\jre\lib\rt.jar;C:\Monika\springboot\javaPratice\target\classes" scaler.ifElse2.Arraylist.Ans
A 1 Stream loop :[1, 2, 3]
A2 iterate by simple for loop :11
A2 iterate by simple for loop :22
A2 iterate by simple for loop :33
A3 iterate by for each :111
A3 iterate by for each :222
A3 iterate by for each :333
[1, 2, 3]
[11, 22, 33]
[111, 222, 333]
A :[[1, 2, 3], [11, 22, 33], [111, 222, 333]]
1
[[1, 2, 3], [11, 22, 33], [111, 222, 333]]
For each stream : [1, 2, 3]
For each stream : [11, 22, 33]
For each stream : [111, 222, 333]
aa :[1, 2, 3]
aaa :1
aaa :2
aaa :3
aa :[11, 22, 33]
aaa :11
aaa :22
aaa :33
aa :[111, 222, 333]
aaa :111
aaa :222
aaa :333
aaa   111111111111111 :1
aaa   111111111111111 :2
aaa   111111111111111 :3
aaa   111111111111111 :11
aaa   111111111111111 :22
aaa   111111111111111 :33
aaa   111111111111111 :111
aaa   111111111111111 :222
aaa   111111111111111 :333

Process finished with exit code 0

Swing Login example with mySql connectivity

 Scenarios:

Create a New Form :

Enter User Name
Enter Mail Id
Enter Password

Login Form :

Enter User Name :
Enter Password :

>>>If user enters 3 times wrong user name or password...Disable both textfield and display message:
>> Communicate to Admin

otherwise if both are correct ....Display message : Login Succesfull.





Click on Button :Existing User Login:





Three time attempt:



Sucessful login:





 

SignUpDemo.java


package swingdbdemoform;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.logging.Level;
import java.util.logging.Logger;
import swingdbdemo.EmployeeEntry;

/**
 *
 * @author monika
 */
public class SignUpDemo extends javax.swing.JFrame {

    /**
     * Creates new form loginDemoValidation
     */
    public SignUpDemo() {
        initComponents();
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                         
    private void initComponents() {

        jLabel1 = new javax.swing.JLabel();
        jLabel2 = new javax.swing.JLabel();
        jLabel3 = new javax.swing.JLabel();
        jTextField1 = new javax.swing.JTextField();
        jTextField3 = new javax.swing.JTextField();
        jButton1 = new javax.swing.JButton();
        jTextField2 = new javax.swing.JTextField();
        jLabel4 = new javax.swing.JLabel();
        jButton2 = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jLabel1.setText("UserName");

        jLabel2.setText("EmailId");

        jLabel3.setText("Password");

        jTextField1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jTextField1ActionPerformed(evt);
            }
        });

        jTextField3.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jTextField3ActionPerformed(evt);
            }
        });

        jButton1.setText("Sign Up");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        jButton2.setText("Existing User login");
        jButton2.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton2ActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                    .addComponent(jLabel4, javax.swing.GroupLayout.PREFERRED_SIZE, 218, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                        .addGroup(layout.createSequentialGroup()
                            .addGap(49, 49, 49)
                            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                                .addGroup(layout.createSequentialGroup()
                                    .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 74, javax.swing.GroupLayout.PREFERRED_SIZE)
                                    .addGap(18, 18, 18)
                                    .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 146, javax.swing.GroupLayout.PREFERRED_SIZE))
                                .addGroup(layout.createSequentialGroup()
                                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                                        .addComponent(jLabel2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                                        .addComponent(jLabel3, javax.swing.GroupLayout.DEFAULT_SIZE, 66, Short.MAX_VALUE))
                                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                                        .addGroup(layout.createSequentialGroup()
                                            .addGap(27, 27, 27)
                                            .addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, 146, javax.swing.GroupLayout.PREFERRED_SIZE))
                                        .addGroup(layout.createSequentialGroup()
                                            .addGap(26, 26, 26)
                                            .addComponent(jTextField2)
                                            .addGap(1, 1, 1))))))
                        .addGroup(layout.createSequentialGroup()
                            .addGap(70, 70, 70)
                            .addComponent(jButton1)
                            .addGap(42, 42, 42)
                            .addComponent(jButton2))))
                .addContainerGap(100, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(27, 27, 27)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel1)
                    .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                            .addComponent(jLabel2)
                            .addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addComponent(jLabel3))
                    .addGroup(layout.createSequentialGroup()
                        .addGap(45, 45, 45)
                        .addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
                .addGap(33, 33, 33)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jButton1)
                    .addComponent(jButton2))
                .addGap(18, 18, 18)
                .addComponent(jLabel4)
                .addContainerGap(114, Short.MAX_VALUE))
        );

        pack();
    }// </editor-fold>                       

    private void jTextField3ActionPerformed(java.awt.event.ActionEvent evt) {                                           
        // TODO add your handling code here:
    }                                          

    private void jTextField1ActionPerformed(java.awt.event.ActionEvent evt) {                                           
        // TODO add your handling code here:
    }                                          

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                        
       
       
        String UserName  =  jTextField1.getText();
        String EmailId   =  jTextField2.getText();
        String Password  =  jTextField3.getText();
       
        String query="insert into login values ('"+UserName+"','"+EmailId+"','"+Password+"')";
       
       
       
       
       
        System.out.println("Query   :"+query);
         String query1="select * from login ";
       
         try {
            // TODO add your handling code here:
 
             Class.forName("com.mysql.jdbc.Driver");
             con=DriverManager.getConnection("jdbc:mysql://localhost:3306/logindb","root","test"); 
       //here sonoo is database name, root is username and password 
     
             st=con.createStatement();
             ResultSet  rs=st.executeQuery(query1); 
             boolean found=false;
             while(rs.next())
             {
                 if(UserName.equals(rs.getString("username")))
                 {
                     found=true;
                     break;
                 }
             }
            if(found==true)
            {
                     jLabel4.setText("UserName is already Existe, Kindly Enter another UserName");
                     jTextField1.setText("");
                     jTextField2.setText("");
                     jTextField3.setText("");
            }
            else
            {
           
             st.executeUpdate(query);   
             jTextField1.setText("");
             jTextField2.setText("");
             jTextField3.setText("");
             jLabel4.setText("UserName is sucessfully signed up!!!!!");
            }
        } catch (ClassNotFoundException ex) {
            Logger.getLogger(EmployeeEntry.class.getName()).log(Level.SEVERE, null, ex);
        } catch (SQLException ex) {
            Logger.getLogger(EmployeeEntry.class.getName()).log(Level.SEVERE, null, ex);
        }
    
    }                                       

    private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                        
        // TODO add your handling code here:
       
        LoginPage loginPage = new LoginPage();
        loginPage.setVisible(true);
    }                                       

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(SignUpDemo.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(SignUpDemo.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(SignUpDemo.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(SignUpDemo.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new SignUpDemo().setVisible(true);
            }
        });
    }
 Connection con;
     Statement st;
    // Variables declaration - do not modify                    
    private javax.swing.JButton jButton1;
    private javax.swing.JButton jButton2;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JLabel jLabel4;
    private javax.swing.JTextField jTextField1;
    private javax.swing.JTextField jTextField2;
    private javax.swing.JTextField jTextField3;
    // End of variables declaration                  
}

LoginPage.java

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package swingdbdemoform;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JButton;
import swingdbdemo.EmployeeEntry;

/**
 *
 * @author monika
 */
public class LoginPage extends javax.swing.JFrame {

    /**
     * Creates new form LoginPage
     */
    public LoginPage() {
        initComponents();
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                         
    private void initComponents() {

        jLabel1 = new javax.swing.JLabel();
        jLabel2 = new javax.swing.JLabel();
        jTextField1 = new javax.swing.JTextField();
        jTextField2 = new javax.swing.JTextField();
        jButton1 = new javax.swing.JButton();
        jLabel3 = new javax.swing.JLabel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jLabel1.setText("UserName");

        jLabel2.setText("Password");

        jButton1.setText("Login");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addGap(79, 79, 79)
                        .addComponent(jButton1)
                        .addGap(38, 38, 38)
                        .addComponent(jLabel3, javax.swing.GroupLayout.PREFERRED_SIZE, 131, javax.swing.GroupLayout.PREFERRED_SIZE))
                    .addGroup(layout.createSequentialGroup()
                        .addGap(59, 59, 59)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                            .addComponent(jLabel2)
                            .addComponent(jLabel1))
                        .addGap(53, 53, 53)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                            .addComponent(jTextField1, javax.swing.GroupLayout.DEFAULT_SIZE, 125, Short.MAX_VALUE)
                            .addComponent(jTextField2))))
                .addContainerGap(95, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(30, 30, 30)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel1)
                    .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(18, 18, 18)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel2)
                    .addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(39, 39, 39)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                    .addComponent(jButton1)
                    .addComponent(jLabel3))
                .addContainerGap(150, Short.MAX_VALUE))
        );

        pack();
    }// </editor-fold>                       

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                        
        String UserName  =  jTextField1.getText();
        String Password  =  jTextField2.getText();
       
         String query1="select * from login ";
       
         try {
            // TODO add your handling code here:
 
             Class.forName("com.mysql.jdbc.Driver");
             con=DriverManager.getConnection("jdbc:mysql://localhost:3306/logindb","root","test"); 
       //here sonoo is database name, root is username and password 
     
             st=con.createStatement();
             ResultSet  rs=st.executeQuery(query1); 
             boolean found=false;
             while(rs.next())
             {
                 if(UserName.equals(rs.getString("username")) && Password.equals(rs.getString("password")))
                 {
                     found=true;
                     break;
                 }
             }
            if(found==true)
            {  
                 homePage.setVisible(true);
                    
            }
            else
            {
            count++;
           
            if(count>3)
            {
              
               jButton1.setEnabled(false);
                jTextField1.setEnabled(false);
                 jTextField2.setEnabled(false);
                  jLabel3.setText("Communicate to Admin!!!!!");
            } else
            {
                jLabel3.setText("Wrong User Name or Password!!!!!");
            }
           
           
            }
        } catch (ClassNotFoundException ex) {
            Logger.getLogger(EmployeeEntry.class.getName()).log(Level.SEVERE, null, ex);
        } catch (SQLException ex) {
            Logger.getLogger(EmployeeEntry.class.getName()).log(Level.SEVERE, null, ex);
        }        // TODO add your handling code here:
    }                                       

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(LoginPage.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(LoginPage.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(LoginPage.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(LoginPage.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new LoginPage().setVisible(true);
            }
        });
    }
     Connection con;
     Statement st;
     HomePage homePage =  new HomePage();
     int count = 0;
    // Variables declaration - do not modify                    
    private javax.swing.JButton jButton1;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JTextField jTextField1;
    private javax.swing.JTextField jTextField2;
    // End of variables declaration                  
}


HomePage.Jave


 /*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package swingdbdemoform;

/**
 *
 * @author monika
 */
public class HomePage extends javax.swing.JFrame {

    /**
     * Creates new form HomePage
     */
    public HomePage() {
        initComponents();
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                         
    private void initComponents() {

        jLabel1 = new javax.swing.JLabel();
        jLabel2 = new javax.swing.JLabel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jLabel2.setBackground(new java.awt.Color(51, 51, 255));
        jLabel2.setFont(new java.awt.Font("Tahoma", 0, 12)); // NOI18N
        jLabel2.setText("Welcome to Home Page");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addGap(86, 86, 86)
                        .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 232, javax.swing.GroupLayout.PREFERRED_SIZE))
                    .addGroup(layout.createSequentialGroup()
                        .addGap(129, 129, 129)
                        .addComponent(jLabel2)))
                .addContainerGap(82, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(24, 24, 24)
                .addComponent(jLabel1)
                .addGap(57, 57, 57)
                .addComponent(jLabel2)
                .addContainerGap(204, Short.MAX_VALUE))
        );

        pack();
    }// </editor-fold>                       

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(HomePage.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(HomePage.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(HomePage.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(HomePage.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new HomePage().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify                    
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    // End of variables declaration                  
}