Answered: implement a database about people, they…

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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Question

implement a database about people, they could be made up, but you want to include a sizable number, maybe 10-20. The data that you store for each person must include a name and at least one additional piece of information, such as a birthday. You can assume that the names are unique. The database should enable you to enter, remove, modify, or search this data. You also should be able to save the data in a file for use later.

Define a class Person to represent a person and another one to represent the database. A dictionary should be a data member of the database class, with Person objects as search keys for this dictionary. Write a program that tests and demonstrates your database.

Expert Solution

Step 1: Code

import java.util.HashSet;

public class Test {

publicstaticclassPerson{

privateStringname;

privateintage;

publicPerson(Stringname, intage){

this.name = name;

this.age = age;

}

publicStringgetName(){returnname;}

publicintgetAge(){returnage;}

publicvoidsetName(Stringname) {this.name = name;}

publicvoidsetAge(intage) {this.age = age;}

}

publicstaticclassPersonDB{

privateHashSet<Person> persons;

publicPersonDB(){

persons = newHashSet<Person>();

}

publicvoidaddPerson(Personperson) {

persons.add(person);

}

publicvoidremovePerson(Personperson) {

persons.remove(person);

}

publicvoidmodifyPerson(Personperson, PersonnewPerson) {

persons.remove(person);

persons.add(newPerson);

}

publicPersonfindPerson(Stringname) {

varcurrentPerson = persons.iterator();

while (currentPerson.hasNext()){

varperson = currentPerson.next();

if (person.getName().equals(name))

returnperson;

}

returnnull;

}

publicvoidprintAllPersons(){

varcurrentPerson = persons.iterator();

while (currentPerson.hasNext()){

varperson = currentPerson.next();

System.out.println("Name: "+person.getName()+" | Age: "+person.getAge());

}

publicstaticvoidmain(String[] args){

vardb = newPersonDB();

varp1 = newPerson("Maurice", 34);

varp2 = newPerson("Kati", 40);

db.addPerson(p1);

db.addPerson(p2);

db.printAllPersons();

varperson = db.findPerson("Maurice");

if(person != null)

System.out.println("Found Maurice");

person = db.findPerson("Joe");

if(person == null)

System.out.println("Did not find Joe");

db.removePerson(p1);

System.out.println("Removed Maurice");

db.printAllPersons();

varnewJane = newPerson("Maron", 44);

db.modifyPerson(p2, newJane);

System.out.println("Updated Maron");

db.printAllPersons();

}

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