Core Java: List and ArrayList Example

Posted by Unknown On 7:36 AM
Views:

List and ArrayList Example: Hi friends this is my first post on core java. I think you know the basics of Collections. I am not explaining basics here. When i am learning java I saw so  many sites are giving examples only on Collections to add integer or string or float. Little bit sites only giving example on adding objects and retrieving  then from Collections. this is my first example using java.util.List and java.util.Arraylist. i am not explaining anything about this example.I think you can understand by seeing this example.

the usage of this example is understanding List and ArrayList and contains method. we are adding employee to a list and avoiding duplicates while adding to list by overriding equals method. and retrieving all employees and displaying them from List. have any questions contact me or post a comment below.

here is the download link for this example. if you free hosting site is deleted this file you can drop your mail id to get this example

Download List and ArrayList Example and open it with eclipse and execute main method


Package structure:



Employee.java

package com.jagadeesh.domain;

public interface Employee {

    public Integer getId();

    public void setId(Integer id);

    public String getFirstName();

    public void setFirstName(String firstName);
    
    public String getLastName();

    public void setLastName(String lastName);
    
    public void setEmail(String email);
    
    public String getEmail();

    public int getPriority();

    public void setPriority(int priority);
    
    public String getDesignation();

    public void setDesignation(String designation);

    public String toDisplayString();
}

EmployeeImpl.java

package com.jagadeesh.domain.impl;

import java.io.Serializable;

import com.jagadeesh.domain.Employee;
import com.jagadeesh.utils.EmployeeIO;

public class EmployeeImpl extends EmployeeIO 
             implements Employee {

 private static final long serialVersionUID = 5058287999709032283L;

 private Integer id;
 private String firstName;
 private String lastName;
 private String email;
 private int priority;
 private String designation;

 @Override
 public Integer getId() {
  return id;
 }

 @Override
 public void setId(Integer id) {
  this.id = id;
 }

 @Override
 public String getFirstName() {
  return firstName;
 }

 @Override
 public void setFirstName(String firstName) {
  this.firstName = firstName;
 }

 @Override
 public String getLastName() {
  return lastName;
 }

 @Override
 public void setLastName(String lastName) {
  this.lastName = lastName;
 }

 @Override
 public String getEmail() {
  return email;
 }

 @Override
 public void setEmail(String email) {
  this.email = email;
 }

 @Override
 public int getPriority() {
  return priority;
 }

 @Override
 public void setPriority(int priority) {
  this.priority = priority;
 }

 @Override
 public String getDesignation() {
  return designation;
 }

 @Override
 public void setDesignation(String designation) {
  if ("CEO".equalsIgnoreCase(designation)) {
   setPriority(1);
  } else if ("MD".equalsIgnoreCase(designation)) {
   setPriority(2);
  } else if ("HR".equalsIgnoreCase(designation)) {
   setPriority(3);
  } else {
   setPriority(4);
  }
  this.designation = designation;
 }

 @Override
 public String toString() {
  StringBuffer buffer = new StringBuffer();
  buffer.append("EmployeeImpl [id=");
  buffer.append(id);
  buffer.append(", firstName=");
  buffer.append(firstName);
  buffer.append(", lastName=");
  buffer.append(lastName);
  buffer.append(", email=");
  buffer.append(email);
  buffer.append(", priority=");
  buffer.append(priority);
  buffer.append(", designation=");
  buffer.append(designation);
  buffer.append("]");
  return buffer.toString();
 }

 @Override
 public boolean equals(Object object) {
  if (object == null)
   return false;
  if (object == this)
   return true;
  if (this.getClass() != object.getClass())
   return false;
  Employee employee = (Employee) object;
  if (this.id.equals(employee.getId())
    && this.firstName.equalsIgnoreCase(employee.getFirstName())
    && this.lastName.equalsIgnoreCase(employee.getLastName())
    && this.email.equalsIgnoreCase(employee.getEmail())
    && this.designation.equalsIgnoreCase(employee.getDesignation()))
   return true;
  return false;
 }

 @Override
 public String toDisplayString() {
  StringBuffer buffer = new StringBuffer();
  buffer.append(this.getId());
  buffer.append("\t");
  buffer.append(this.getFirstName());
  buffer.append("\t");
  buffer.append(this.getLastName());
  buffer.append("\t");
  buffer.append(this.getEmail());
  buffer.append("\t");
  buffer.append(this.getDesignation());
  return buffer.toString();
 }
}

EmployeeService.java

package com.jagadeesh.service;

import java.util.List;

import com.jagadeesh.domain.Employee;

public interface EmployeeService {

    List<Employee> getAll();

    void addEmployee(Employee employee);

}

EmployeeServiceImpl.java

package com.jagadeesh.service.impl;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import com.jagadeesh.domain.Employee;
import com.jagadeesh.service.EmployeeService;

public class EmployeeServiceImpl implements EmployeeService {
 private List<Employee> employees = new ArrayList<Employee>();

 @Override
 public List<Employee> getAll() {
  List<Employee> employees = new ArrayList<Employee>(this.employees);
  return Collections.unmodifiableList(employees);
 }

 @Override
 public void addEmployee(Employee employee) {
  if (employees.contains(employee)) {
   System.out.println("Employee already exists");
  } else {
   this.employees.add(employee);
  }
 }
}

EmployeeIO.java

package com.jagadeesh.utils;

import java.util.List;

import com.jagadeesh.domain.Employee;
import com.jagadeesh.domain.impl.EmployeeImpl;


public class EmployeeIO {

 public static Employee read() {
  Employee employee = new EmployeeImpl();
  employee.setId(KeyBoard.readInt("Enter Id :"));
  employee.setFirstName(KeyBoard.read("Enter First Name :"));
  employee.setLastName(KeyBoard.read("Enter Last Name :"));
  employee.setEmail(KeyBoard.read("Enter Email :"));
  employee.setDesignation(KeyBoard.read("Enter Designation :"));
  return employee;
 }

 public static void out(List<Employee> employees) {
  StringBuilder builder = new StringBuilder();
  builder.append("Id\t\tFirst Name\t\tLast Name\t\tEmail\ttDesignation\n");
  for (int i = 0; i < employees.size(); i++) {
   builder.append(employees.get(i).toDisplayString());
   builder.append("\n");
  }
  System.out.println(builder);
 }

}
KeyBoard.java 
package com.jagadeesh.utils;

import java.util.Scanner;

public class KeyBoard {
  
    public static int readInt(String message) {
        System.out.print(message);
        Scanner scanner = new Scanner(System.in);
        try {
            int number = Integer.parseInt(scanner.next());
            return number;
        }
        catch(NumberFormatException e) {
            System.out.println("Invalid Number");
            return readInt(message);
        }            
    }
    
    public static String read(String message) {
        System.out.print(message);
        Scanner scanner = new Scanner(System.in);
        return scanner.nextLine();
    }    
}
EmployeeMain.java 
package com.jagadeesh.main;

import com.jagadeesh.domain.Employee;
import com.jagadeesh.service.EmployeeService;
import com.jagadeesh.service.impl.EmployeeServiceImpl;
import com.jagadeesh.utils.EmployeeIO;
import com.jagadeesh.utils.KeyBoard;

public class EmployeeMain {
    public static void main(String[] args) throws Exception {
        int option = 1;
        EmployeeService empService = new EmployeeServiceImpl();
        do {
            Employee employee = EmployeeIO.read();
            empService.addEmployee(employee);
            option = KeyBoard.readInt(
                    "Do you want add another employee(1/0) :");
            
        } while(option == 1);
        System.out.println("Reading from List");
        EmployeeIO.out(empService.getAll());
    }
}
Out put of the program

Enter Id :1
Enter First Name :jagadeesh
Enter Last Name :kumar
Enter Email :mannejkumar@gmail.com
Enter Designation :developer
Do you want add another employee(1/0) :1
Enter Id :2
Enter First Name :jagadeesh
Enter Last Name :kumar
Enter Email :mannejkumar@gmail.com
Enter Designation :developer
Do you want add another employee(1/0) :1
Enter Id :1
Enter First Name :jagadeesh
Enter Last Name :kumar
Enter Email :mannejkumar@gmail.com
Enter Designation :developer
Employee already exists
Do you want add another employee(1/0) :testing invalid option
Invalid Number
Do you want add another employee(1/0) :1
Enter Id :3
Enter First Name :jagadeesh
Enter Last Name :kumar
Enter Email :admin@myrmidons.co.in
Enter Designation :developer
Do you want add another employee(1/0) :0
Reading from List
Id First Name Last Name Email  Designation
1 jagadeesh kumar mannejkumar@gmail.com developer
2 jagadeesh kumar mannejkumar@gmail.com developer
3 jagadeesh kumar admin@myrmidons.co.in developer
i am not uploading this example. free file hosting sites removing files. if you want this example please drop your mail id or contact mannejkumar@gmail.com. for more information follow our fan page on facebook




Categories:

Site search