This exercise implements the class Persons and Phonebook and then adds Persons into an ArrayList in Phonebook.
My Code
Main
public class Main {
public static void main(String[] args) {
Phonebook phonebook = new Phonebook();
phonebook.add("Pekka Mikkola", "040-123123");
phonebook.add("Edsger Dijkstra", "045-456123");
phonebook.add("Donald Knuth", "050-222333");
String number = phonebook.searchNumber("Pekka Mikkola");
System.out.println( number );
number = phonebook.searchNumber("Martti Tienari");
System.out.println( number );
}
}Person
public class Person {
private String name;
private String number;
public Person(String name, String number){
this.name = name;
this.number = number;
}
public String getName(){
return this.name;
}
public String getNumber(){
return this.number;
}
public void changeNumber(String newNumber){
this.number = newNumber;
}
public String toString(){
return this.name + " number: " + this.number;
}
}Phonebook
import java.util.ArrayList;
public class Phonebook {
private ArrayList<Person> phonebook = new ArrayList<Person>();
public Phonebook() {
}
public void add(String name, String number) {
Person person = new Person(name, number);
this.phonebook.add(person);
}
public String searchNumber(String name) {
for (Person person : phonebook) {
if (person.getName() == name) {
return person.getNumber();
}
}
return "number not known";
}
public void printAll() {
for (Person person : phonebook) {
System.out.println(person);
}
}
}
Model Code
Main
public class Main {
public static void main(String[] args) {
Phonebook phonebook = new Phonebook();
phonebook.add("Pekka Mikkola", "040-123123");
phonebook.add("Edsger Dijkstra", "045-456123");
phonebook.add("Donald Knuth", "050-222333");
String number = phonebook.searchNumber("Pekka Mikkola");
System.out.println( number );
number = phonebook.searchNumber("Martti Tienari");
System.out.println( number );
}
}Person
public class Person {
private String name;
private String number;
public Person(String name, String number) {
this.name = name;
this.number = number;
}
@Override
public String toString() {
return name+" number: "+number;
}
public String getName() {
return name;
}
public String getNumber() {
return number;
}
public void changeNumber(String newNumber){
number = newNumber;
}
}Phonebook
import java.util.ArrayList;
public class Phonebook {
private ArrayList<Person> list;
public Phonebook() {
list = new ArrayList<Person>();
}
public void add(String name, String number) {
list.add(new Person(name, number));
}
public void printAll() {
for (Person person : list) {
System.out.println(person);
}
}
public String searchNumber(String name) {
for (Person person : list) {
if (person.getName().equals(name)) {
return person.getNumber();
}
}
return "number not known";
}
}Comments
OK, so I didn’t do so well in this one. I have a redundant ArrayList delaration at the top of Phonebook, haven’t done the constructor correctly and I used == to compare strings instead of .equals(name).