So my issue is trying to use the getName() and getPhone() methods (in class Contact) in the main method.
I don't know how to use them in this context with all 3 classes.
Here is what the program is supposed to be doing
Apologies if this is not too concise, I just started programming recently.
public class LookupPhonebook{
public static void main(String[] args) {
Phonebook phonebook = new Phonebook("Sam Johnson");
phonebook.addContact(new Contact("Kelly Wong", "(02) 12345678"));
phonebook.addContact(new Contact("Richard Jackson", "(02) 87654321"));
phonebook.show();
String searchName = Input.askString("Enter a contact name: ");
phonebook.findContactByName(searchName);
if (searchName.equals(phonebook.getName())) {
System.out.println("Phone number is " + phonebook.getPhone());
}
else {
System.out.println(searchName + " not found");
}
}
}
import java.util.*;
public class Phonebook {
private String owner;
private ArrayList<Contact> contacts = new ArrayList<Contact>();
public Phonebook(String owner) {
this.owner = owner;
}
public void addContact(Contact contact) {
contacts.add(contact);
}
public void show(){
System.out.println(owner + "'s phonebook");
for (Contact contact : contacts) {
System.out.println(contact);
}
}
public Contact findContactByName(String name) {
for (Contact contact : contacts) {
if (contact.getName().equals(name)) {
return contact;
}
else {
continue;
}
}
return null;
}
}
public class Contact {
private String name;
private String phone;
public Contact(String name, String phone) {
this.name = name;
this.phone = phone;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public String toString() {
return name + ": " + phone;
}
}
This method is the only one used in a class provided to help with the exercise.
/**
* Asks the user the given question, waits for the user to enter a
* single character at the keyboard, and then returns this character.
*
* #param question the question to be printed
* #return the character that the user entered as an answer to the question
*/
public static char askChar(String question) {
System.out.print(question + " ");
return scanner.nextLine().charAt(0);
}
You need to store the result from findContactByName to a local variable following the instruction. The original program just throw away the result.
public static void main(String[] args) {
Phonebook phonebook = new Phonebook("Sam Johnson");
phonebook.addContact(new Contact("Kelly Wong", "(02) 12345678"));
phonebook.addContact(new Contact("Richard Jackson", "(02) 87654321"));
phonebook.show();
String searchName = Input.askString("Enter a contact name: ");
// 2. Search contact and store is local variable
Contact result = phonebook.findContactByName(searchName);
// 3. If we found contact
if (result != null) {
System.out.println("Phone number is " + result.getPhone());
} else {
// 4. No contact is found
System.out.println(searchName + " not found");
}
}
Related
I got 2 classes
class Curso{
private String name;
public Curso(String nome){
this.name = nome;
}
public String getName(){
return this.name;
}
}
and
public class testaCurso{
public static void main(String[] args){
Course c1 = new Course("Computer Science");
c1.addDisciplina("AlgProgII");
c1.addDisciplina("SO");
c1.addDisciplina ("Grafos");
System.out.println(c1);
}
}
i gotta modify the Course class so that it can store the names of the Disciplina that make up the course and work for the test above with the output as shown. Consider that a course will not have a maximum of 50 subjects.
output:
Course: Computer Science,
Disciplinas:{ AlgProgII SO Grafos }
class Curso {
private String name;
// Add an list field containg the disciplinas
private final List<String> disciplinas = new ArrayList<>();
public Curso(String name){
this.name = name;
}
public String getName(){
return this.name;
}
// Add a `addDisciplina` method
public void addDisciplina(String name) {
disciplinas.add(name);
}
// Override the `toString` method
#Override
public String toString() {
return "Course: " + name + ", Disciplinas: + ", disciplinas;
}
}
We can implement toString() like the following:
public class Course {
private final String name;
private final List<String> disciplinas;
public Course(String name){
this.name = name;
this.disciplinas = new ArrayList<>();
}
public Course(String name, List<String> disciplinas){
this.name = name;
this.disciplinas = new ArrayList<>(disciplinas);
}
public void addDisciplinas(String discplina){
this.disciplinas.add(discplina);
}
#Override
public String toString() {
return "Course: " + name + ", Disciplinas: {" + disciplinas.stream().collect(Collectors.joining(" ")) +"}";
}
}
Usage:
Course course = new Course("Computer Science", Arrays.asList("AlgProgII", "SO", "Grafos"));
System.out.println(course);
Output:
Course: Computer Science, Disciplinas: {AlgProgII SO Grafos}
So I am creating a program that reads customer details and order details from two different files. I created methods to read the file, store the data in the object of customers and then add the object of customers into linkedlist.. Now when I try doing the same for order file, I am getting the wrong output. so in the code shown below, I am trying to check if the customer name entered in order file matches the name stored in customer linkedlist.. So say I have two rows in the order.txt file:
Ord101 true James
Ord102 false Jim
with what I have done, I get the following output:
Ord102 false Jim
Ord102 false Jim
instead of getting the correct output which would be:
Ord101 true James
Ord102 false Jim
because both, James and Jim are names present in Customer file and linkedlist. So here is my code for reading order file:
public void readFileOrder() {
Scanner y;
String b,c,d;
LinkedList<Customers> list=new LinkedList<Customers>(); //another method was already created to add data inside list and its working so list contains data
LinkedList<order> list1=new LinkedList<order>();
Boolean isOpen;
order Order1=new order();
while(y.hasNext())
{
b=y.next();
isOpen=y.nextBoolean();
d=y.next();
System.out.println(list);
Customers customers1=new Customers();
for(int i=0;i<list.size();i++) //this is where i'm checking if the customer name in the order file matches the value in list
{
if(list.get(i).getName().equals(d))
{
customers1=list.get(i);
Order1.setCustomer(customers1);
Order1.setName(b);
Order1.setIsOpen(isOpen);
list1.add(Order1);
}
}
}
for(int j=0;j<list1.size();j++)
{
System.out.println(list1.get(j).getCustomer()+" and "+list1.get(j).getName()+" and "+list1.get(j).getIsOpen());
}
}
just in case, provided below are Customer and order class:
import java.util.LinkedList;
public class Customers {
#Override
public String toString() {
return "Customers [Name=" + Name + ", age=" + age + ", email=" + email + ", Address=" + Address + "]";
}
String Name;
int age;
String email;
String Address;
public String getName() {
return Name;
}
public void setName(String name) {
Name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getAddress() {
return Address;
}
public void setAddress(String address) {
Address = address;
}
public void removeCustomer(String name2, LinkedList<Customers> list) {
for(int k=0;k<list.size();k++)
{
if(list.get(k).getName().equals(name2))
{
list.remove(list.get(k));
}
}
}
}
order class:
import java.util.LinkedList;
public class order{
String name;
Boolean isOpen;
Customers customer;
String cusName;
public order() {
super();
}
public String getName() {
return name;
}
public order(Customers customer) {
super();
this.customer = customer;
}
public void setName(String name) {
this.name = name;
}
public Boolean getIsOpen() {
return isOpen;
}
public void setIsOpen(Boolean isOpen) {
this.isOpen = isOpen;
}
public String getCustomer() {
return customer.getName();
}
public void setCustomer(Customers customer) {
this.customer=customer;
this.cusName=customer.getName();
}
}
You are adding references to the same order to the list over and over again, each time overwriting the attributes set in the previous iteration of the loop. Instead, create a new order inside the loop.
In other words, change this:
order Order1=new order();
while(y.hasNext()) {
to this:
while(y.hasNext()) {
order Order1=new order();
So here is assignment :
A student entity has a name and an address (both represented by an object of class Name and Address), in addition to a university ID, and a course schedule represented by an ArrayList of Courses
Your code should not allow the creation of Two students with the same university ID
So I'm thinking of using ArrayList to hold a list of student and check if student exists or not before create a new student. sorry, this is my first question so I'm trying my best to explain it:
This is my Address class:
public class Address {
private int streetNumber;
private String streetName;
private String city;
private String state;
private int province;
private String country;
public Address (int streetNumber,String streetName,String city,String state,int province,String country)
{
this.streetNumber=streetNumber;
this.streetName=streetName;
this.city=city;
this.state=state;
this.province=province;
this.country=country;
}
public int getStreetNumber() {
return streetNumber;
}
public void setStreetNumber(int streetNumber) {
this.streetNumber = streetNumber;
}
public String getStreetName() {
return streetName;
}
public void setStreetName(String streetName) {
this.streetName = streetName;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public String getState() {
return state;
}
public void setState(String state) {
this.state = state;
}
public int getProvince() {
return province;
}
public void setProvince(int province) {
this.province = province;
}
public String getCountry() {
return country;
}
public void setCountry(String country) {
this.country = country;
}
public String toString() {
return " [streetNumber=" + streetNumber + ", streetName=" + streetName
+ ", city=" + city + ", state=" + state + ", province="+province+", country="
+ country + "]";
}
public boolean equals(Address add)
{
if(add==null)
{
return true;
}
if(this.getClass()!=add.getClass())
{
return false;
}
Address address=(Address) add;
return streetNumber==address.streetNumber &&
province==address.province && streetName.equals(address.streetName)
&& city.equals(address.city)&& state.equals(address.state)&& country.equals(address.country);
}
}
This is my Name class
public class Name {
private String firstName;
private String lastName;
private char middle;
public Name (String fiName,String laName, char middle)
{
this.firstName=fiName;
this.lastName=laName;
this.middle=middle;
}
public String getFirst()
{
return firstName;
}
public void setFirst(String first)
{
firstName=first;
}
public String getLast()
{
return lastName;
}
public void setLast(String last)
{
lastName=last;
}
public char getMiddle()
{
return middle;
}
public void setMiddle(char midd)
{
middle=midd;
}
/*public String toString()
{
return "[First Name= "+ firstName +" Last Name "+ lastName+" Middle Name "+ middle +"";
}*/
}
This is my Student class:
public class Student {
private int studentId;
private Name name;
private Address address;
boolean a;
ArrayList<Course> courseSchedule = new ArrayList<Course>();
ArrayList<Student> student=new ArrayList<Student>();
public Student(String fiName,String laName, char middle,int stNumber,String stName,String city,String state,int province,String country,int id)
{
if(student.contains(id))
{
System.out.println("Student cannot be same id");
}
else
{
address= new Address(stNumber,stName,city,state,province,country);
name=new Name(fiName,laName,middle);
this.studentId=id;
student.add();
}
}
public int getID()
{
return studentId;
}
public void setId(int id)
{
this.studentId = id;
}
public ArrayList<Course> getCourseSchedule()
{
return courseSchedule;
}
public void setCourseSchedule(ArrayList<Course> courseSchedule)
{
this.courseSchedule = courseSchedule;
}
public void addCourse(Course c) {
courseSchedule.add(c);
}
public void dropCourse(Course course) {
courseSchedule.remove(course);
}
}
My question is how can you add Student Object into Student ArrayList
and how can I check if the Student Id exists in ArrayList with contains() method
student.contains(id) this line right here it does not seem to be right
I hope im explain my question a little clear now. Sorry for my english also.
You would not keep a list of Student objects within the class for Student. Your ArrayList<Student> student=new ArrayList<Student>(); does not belong there.
You would have another structure or collection kept elsewhere named something like StudentBody. When a student is instantiated, it is added to the StudentBody collection.
List< Student > studentBody = new ArrayList< Student >() ; // This list is stored somewhere else in your app.
You could loop a List of Student objects in the StudentBody object. For each you would access the UniversityId member field and compare to your new one being added.
Or you could use a Map, where the key is a UniversityId object and the value is a Student object. Check for an existing key before adding.
These solutions ignore the important issue of concurrency. But that is likely okay for a homework assignment in a beginning course in programming.
Use A HashMap() for collecting information based on unique Ids.
public class Student {
private int studentId;
private Name name;
private Address address;
private static HashMap<Integer,Student> students = new ConcurrentHashMap<>(); // Make a static Map so all objectrs shared same data
public Student(String fiName,String laName, char middle,int stNumber,String stName,String city,String state,int province,String country,int id)
{
if(students.contains(id))
{
System.out.println("Student can be same id");
}
else
{
address= new Address(stNumber,stName,city,state,province,country);
name=new Name(fiName,laName,middle);
this.studentId=id;
students.put(id,this); // use this to add current object
}
}
Im trying to create a student class, a course class and the main class. I am trying to add students to the course, and when students are added to the class the number of students in the course should increase, when the the code is run it should print the course details followed by the students in the course.
I have got the following code:
Main class:
public class JavaLecture3 {
public static final int DEBUG = 0;
public static void main(String [] args){
//Student student = new Student(); // Calling default constructor here.
Course course = new Course();
student = new Student(21, "Joe", "CSE", "07447832342");
course = new Course("CSE", "Tom", 5);
System.out.println("Course Information: ");
System.out.println("-------------------");
System.out.println(course);
System.out.println();
System.out.println("Student contains: "); // calls student.toString());
System.out.println("-------------------");
System.out.println(student);
}
}
Course class:
public class Course {
ArrayList<Student> studentList;
private String courseName;
private String teacher;
private int noOfStudents;
//Getters
public String getCourseName(){
return this.courseName;
}
public int getNoOfStudents(){
return this.noOfStudents;
}
public String getTeacher(){
return this.teacher;
}
//Setters
public void setCourseName(String courseName){
this.courseName = courseName;
}
public void setNoOfStudents(int noOfStudents){
this.noOfStudents = noOfStudents;
}
public void setTeacher(String teacher){
this.teacher = teacher;
}
/**
* Default constructor. Populates course name, number of students with defaults
*
*/
public Course(){
this.noOfStudents = 0;
this.courseName = "Not Set";
this.teacher = "Not Set";
studentList = new ArrayList<Student>();
}
/**
* Constructor with parameters
* #param noOfStudents integer
* #param courseName String with the Course name
* #param teacher String with the teacher
*/
public Course(String courseName, String teacher, int noOfStudents){
this.courseName = courseName;
this.teacher = teacher;
noOfStudents = noOfStudents;
studentList = new ArrayList<Student>();
}
public static void addStudent(Student newStudent){
if(studentList.size()==noOfStudents){
System.out.println("The class is full, you cannot enrol.");
}
else {
studentList.add(newStudent);
}
}
public String toString() {
return "Course Name: " + this.courseName + " Teacher: " + this.teacher
+ " Number of Students: " + this.noOfStudents;
}
}
Student class:
public class Student {
private String name;
private int age;
public String gender = "na";
private String course;
private String phoneNo;
public static int instances = 0;
// Getters
public int getAge(){
return this.age;
}
public String getName(){
return this.name;
}
public String getCourse(){
return this.course;
}
public String getPhoneNo(){
return this.phoneNo;
}
// Setters
public void setAge(int age){
this.age = age;
}
public void setName(String name){
if (JavaLecture3.DEBUG > 3) System.out.println("In Student.setName. Name = "+ name);
this.name = name;
}
public void setCourse(String course){
this.course = course;
}
public void setPhoneNo(String phoneNo){
this.phoneNo = phoneNo;
}
/**
* Default constructor. Populates name,age,gender,course and phone Number
* with defaults
*/
public Student(){
instances++;
this.age = 18;
this.name = "Not Set";
this.gender = "Not Set";
this.course = "Not Set";
this.phoneNo = "Not Set";
}
/**
* Constructor with parameters
* #param age integer
* #param name String with the name
* #param course String with course name
* #param phoneNo String with phone number
*/
public Student(int age, String name, String course, String phoneNo){
this.age = age;
this.name = name;
this.course = course;
this.phoneNo = phoneNo;
}
/**
* Gender constructor
* #param gender
*/
public Student(String gender){
this(); // Must be the first line!
this.gender = gender;
}
protected void finalize() throws Throwable{
//do finalization here
instances--;
super.finalize(); //not necessary if extending Object.
}
public String toString (){
return "Name: " + this.name + " Age: " + this.age + " Gender: "
+ this.gender + " Course: " + this.course + " Phone number: "
+ this.phoneNo;
}
}
Reference:
http://docs.oracle.com/javase/7/docs/api/java/util/ArrayList.html?is-external=true
Course.getNoOfStudents should just return studentList.size(). No need to maintain a separate variable.
To print a list of students (from Course):
for(int i=0;i<studentList.size();i++) System.out.println(studentList.get(i));
Since you initialized the array list in the Course class, you should add the students to it. You should create a method in Course that adds an object to the array list such as:
public void addStudent(Student s){
studentList.add(s);
noOfStudents++;
}
To add multiple students:
public void addStudents(Student[] students){
for(int i = 0; i < students.length; i++){
studentList.add(students[i]);
}
}
You're almost there, just use the .add method made for you in the array list.
public class JavaLecture3 {
public static final int DEBUG = 0;
public static void main(String [] args){
Student student = new Student(); // Calling default constructor here.
Course course = new Course();
student = new Student(21, "Joe", "CSE", "07447832342");
course = new Course("CSE", "Tom", 5);
course.addStudent(student);
System.out.println("Course Information: ");
System.out.println("-------------------");
System.out.println(course);
System.out.println();
System.out.println("Student contains: "); // calls student.toString());
System.out.println("-------------------");
System.out.println(student);
}
}
public class Course {
List<Student> studentList;
private String courseName;
private String teacher;
private int noOfStudents;
// Getters
public String getCourseName() {
return this.courseName;
}
public int getNoOfStudents() {
return this.noOfStudents;
}
public String getTeacher() {
return this.teacher;
}
// Setters
public void setCourseName(String courseName) {
this.courseName = courseName;
}
public void setNoOfStudents(int noOfStudents) {
this.noOfStudents = noOfStudents;
}
public void setTeacher(String teacher) {
this.teacher = teacher;
}
/**
* Default constructor. Populates course name, number of students with
* defaults
*
*/
public Course() {
this.noOfStudents = 0;
this.courseName = "Not Set";
this.teacher = "Not Set";
studentList = new ArrayList<Student>();
}
/**
* Constructor with parameters
*
* #param noOfStudents
* integer
* #param courseName
* String with the Course name
* #param teacher
* String with the teacher
*/
public Course(String courseName, String teacher, int noOfStudents) {
this.courseName = courseName;
this.teacher = teacher;
this.noOfStudents = noOfStudents;
studentList = new ArrayList<Student>();
}
public void addStudent(Student newStudent) {
if (studentList.size() == noOfStudents) {
System.out.println("The class is full, you cannot enrol.");
} else {
studentList.add(newStudent);
}
}
#Override
public String toString() {
return "Course Name: " + this.courseName + " Teacher: " + this.teacher
+ " Number of Students: " + studentList.size();
}
}
public class Student {
private String name;
private int age;
public String gender = "na";
private String course;
private String phoneNo;
public static int instances = 0;
// Getters
public int getAge() {
return this.age;
}
public String getName() {
return this.name;
}
public String getCourse() {
return this.course;
}
public String getPhoneNo() {
return this.phoneNo;
}
// Setters
public void setAge(int age) {
this.age = age;
}
public void setName(String name) {
if (JavaLecture3.DEBUG > 3)
System.out.println("In Student.setName. Name = " + name);
this.name = name;
}
public void setCourse(String course) {
this.course = course;
}
public void setPhoneNo(String phoneNo) {
this.phoneNo = phoneNo;
}
/**
* Default constructor. Populates name,age,gender,course and phone Number
* with defaults
*/
public Student() {
instances++;
this.age = 18;
this.name = "Not Set";
this.gender = "Not Set";
this.course = "Not Set";
this.phoneNo = "Not Set";
}
/**
* Constructor with parameters
*
* #param age
* integer
* #param name
* String with the name
* #param course
* String with course name
* #param phoneNo
* String with phone number
*/
public Student(int age, String name, String course, String phoneNo) {
this.age = age;
this.name = name;
this.course = course;
this.phoneNo = phoneNo;
}
/**
* Gender constructor
*
* #param gender
*/
public Student(String gender) {
this(); // Must be the first line!
this.gender = gender;
}
protected void finalize() throws Throwable {
// do finalization here
instances--;
super.finalize(); // not necessary if extending Object.
}
public String toString() {
return "Name: " + this.name + " Age: " + this.age + " Gender: "
+ this.gender + " Course: " + this.course + " Phone number: "
+ this.phoneNo;
}
}
public class JavaLecture3 {
public static final int DEBUG = 0;
public static void main(String [] args){
//Create course object
Course course = new Course("CSE", "Tom", 5);
Scanner scanner = new Scanner(System.in);
String cmd = "Yes";
while(cmd.equals("Yes")){
Student student = new Student();
System.out.print("Enter a new student? ");
cmd = scanner.next();
if (cmd.equals("Yes")){
//Read student name
System.out.print("Enter a student name: ");
String name = scanner.next();
student.setName(name);
//Read student Age
System.out.print("Enter a student age: ");
int age = scanner.nextInt();
student.setAge(age);
//Read student Course
System.out.print("Enter a student course: ");
String stdent_course = scanner.next();
student.setCourse(stdent_course);
//register the student to the class
course.addStudent(student);
}
}
scanner.close();
System.out.println("Course Information: ");
System.out.println("-------------------");
System.out.println(course.toString());
System.out.println();
}
}
I reworked a bit your toString() method from Course class. This should print the list of students attending a class.
public String toString (){
String ret_value = "Name: " + this.name + " Age: " + this.age + " Gender: "
+ this.gender + " Course: " + this.course + " Phone number: "
+ this.phoneNo + " Students attending this course:";
for (Student student: studentList) {
ret_value = ret_value + " " + Student.getName();
}
return ret_value;
}
I am supposed to come up with this output.
But I am getting this instead..
Here is my code:
import java.lang.*;
import java.util.*;
import java.io.*;
public class Sample{
private String name;
private Hashtable customers = new Hashtable();
private Hashtable movies = new Hashtable();
public Sample(String aName){
name = aName;
}
public String getName(){
return name;
}
public void setName(String aName){
name = aName;
}
public void addCustomer (Customer customer) {
customers.put(customer.getName(), customer);
}
public Customer getCustomer (String customerName) {
return (Customer)customers.get(customerName);
}
public void addMovie (Movie movie) {
movies.put(movie.getName(), movie);
}
public Movie getMovie (String movieName) {
return (Movie)movies.get(movieName);
}
public void error (String message) {
System.out.println ("ERROR: " + message);
}
public Enumeration getMovies() {
return movies.elements();
}
public Enumeration getCustomers() {
return customers.elements();
}
public void showAll() {
System.out.println ("name: "+ this.getName());
Enumeration kk = this.getCustomers();
while (kk.hasMoreElements()) {
Customer one = (Customer) kk.nextElement();
System.out.println (one.show());
}
Enumeration ff = this.getMovies();
while (ff.hasMoreElements()) {
Movie one = (Movie) ff.nextElement();
System.out.println (one.show());
}
}
public void test() {
Customer k1 = new Customer ("Jonah") ; this.addCustomer (k1);
Customer k2 = new Customer ("Hellen") ; this.addCustomer (k2);
Customer k3 = new Customer ("Agnes") ; this.addCustomer (k3) ;
Movie f1 = new Movie ("StarWars"); this.addMovie (f1) ;
Movie f2 = new Movie ("Shrek"); this.addMovie (f2) ;
System.out.println("-**-**- test part 1 -**-**-") ;
this.showAll();
System.out.println("-**-**- test part 2 -**-**-") ;
System.out.println("---" + k1.getName() + " rents " + f1.getName());
this.showAll();
k1.doRent(f1);
MY CUSTOMER CLASS:
package eric;
public class Customer {
String name;
public Customer(String nameCus){
name = nameCus;
}
public String getName(){
return name;
}
public String show(){
return name;
}
public void doRent(Movie f1) {
System.out.println(" -"+ " RentData" + "[" + getName() +"," + f1.getName() + "]" );
}
}
MY MOVIE CLASS:
public class Movie {
String name;
int x = 0;
public Movie(String nameMov){
name = nameMov;
}
public String getName(){
return name;
}
public String show(){
return name+"\n"+" - average: "+x +" days\n"+" - number of rentings: "+x ;
}
}
My problem is that i cannot find a way to fix -RentData [Jonah,StarWars] under the name Jonah... Instead it comes at the end of output.. I need some one to help me figure how am ganna do that.. thanks
You're calling k1.doRent(f1) before this.showAll() so naturally you will get the "RentData..." line printed before the names are printed. The way your code is now is not conducive to what you're trying to do at all. Your Customer class should have a member list called rentedMovies that is populated every time you call doRent(...) on a Customer object. Then, Customer.show() should print the name of the customer, followed by your "RentData..." stuff that comes from rentedMovies.