Develop Reference

I am trying to print out the Address a1 of an object person p1 I created. The Person constructor takes in the Address object as well

public class Person {
enum Sex{Male, Female}
private String initials;
private String lastname;
private String firstname;
private Sex sex;
private int yearOfBirth;
private double netWorth;
private Address homeaddress;
Sex male = Sex.Male;
Sex female = Sex.Female;
public Person(){}
public Person(String firstname, String lastname, int yearOfBirth, Sex sex, double netWorth, Address homeaddress)
{
this.netWorth = netWorth;
this.firstname = firstname;
this.lastname = lastname;
this.sex = sex;
this.homeaddress = homeaddress;
this.male = Sex.Male;
this.female = Sex.Female;
}
public void updateNetworth(double x)
{
this.netWorth = netWorth + x;
}
public String toString(){
return("\nName: " + this.firstname + this.lastname + "\n" +
"Address: " + this.homeaddress + "\nNet Worth: " + this.netWorth);
}
public static void main(String[] args)
{
Address a1 = new Address (258, "Masachu","New York","USA");
Person p1 = new Person("John","Brown",1998,Sex.Male,1000.00,a1);
System.out.println(p1.toString());
p1.updateNetworth(1000.00);
System.out.println(p1.toString());
}
}
public class Address {
private int streetNumber;
private String streetName;
private String city;
private String country;
public Address (int streetNumber, String streetName, String city, String country)
{
this.streetNumber = streetNumber;
this.streetName = streetName;
this.city = city;
this.country = country;
}
}
Whenever I run this my Address field is being printed out as Address#3feba861. I am unclear as to why this is so. So my Person constructor takes in the Address object, but it seems that I cannot print out the person object with the address in this way. How do I go about fixing this.

#Override
public String toString() {
return "Address{" +
"streetNumber=" + streetNumber +
", streetName='" + streetName + '\'' +
", city='" + city + '\'' +
", country='" + country + '\'' +
'}';
}

While Iterating through ArrayList using for loop instead of Iterator, why does the output reference an address instead of actual object?

I've created a list from objects from my user defined class called students.
class Student {
String name, phone, group;
Student(String name, String phone, String group) {
this.name = name;
this.phone = phone;
this.group = group;
}
}
And accessed it in the following way:
public static void main(String[] args) {
Student s1 = new Student("Ayush", "9841293412", "L1N1");
Student s2 = new Student("Rahul", "9842432423", "L1M1");
Student s3 = new Student("Gaurav", "984129231", "L1N2");
ArrayList<Student> al = new ArrayList<Student>();
al.add(s1);
al.add(s2);
al.add(s3);
al.add(s4);
al.add(s5);
for(Student name:al){
System.out.println("Name: " + name);
}
But the output is referencing object like following:
Name: Student#1baf61
Name: Student#b5272
I don't know why this has happened.

Just extract the name field instead:
class Student {
String name, phone, group;
Student(String name, String phone, String group) {
this.name = name;
this.phone = phone;
this.group = group;
}
public String getName() {
return name;
}
#Override
public String toString() {
return "Student{" +
"name='" + name + '\'' +
", phone='" + phone + '\'' +
", group='" + group + '\'' +
'}';
}
public static void main(String[] args) {
Student s1 = new Student("Ayush", "9841293412", "L1N1");
Student s2 = new Student("Rahul", "9842432423", "L1M1");
Student s3 = new Student("Gaurav", "984129231", "L1N2");
ArrayList<Student> al = new ArrayList<Student>();
al.add(s1);
al.add(s2);
al.add(s3);
for (Student name : al) {
System.out.println("Name: " + name.name);
System.out.println("Name: " + name.getName()); // Using a getter
System.out.println(name); // Using toString
}
}
}
As a best practice use a getter or a toString implementation to better represent your model

You can override the toString method in your StudentClass or if u want only the name you can implement a getter method in your StundentClass..
class Student {
String name, phone, group;
Student(String name, String phone, String group) {
this.name = name;
this.phone = phone;
this.group = group;
}
public String getName() {
return name;
}
#Override
public String toString() {
return "Student{" +
"name='" + name + '\'' +
", phone='" + phone + '\'' +
", group='" + group + '\'' +
'}';
}
usage toString
for(Student name:al){
System.out.println("Name: " + name);
}
output:
Name: Student{name='Ayush', phone='9841293412', group='L1N1'}
Name: Student{name='Rahul', phone='9842432423', group='L1M1'}
Name: Student{name='Gaurav', phone='984129231', group='L1N2'}
usage of your getter
for(Student name:al){
System.out.println("Name: " + name.getName());
}
output:
Name: Ayush
Name: Rahul
Name: Gaurav

how to sort an array of string records using comparator in java?

i have a string array data comprising of individual records. i.e., firstname,lastname,age,emailid,sex,address.
example:
static String[] users = {"Lola,Grimsdyke,89,lgrimsdyke0#facebook.com,Female,Newport Beach,CA","Sybilla,Martinetto,84,smartinetto1#google.it,Female,Anniston,AL","Casi,Roizn,78,croizn2#scribd.com,Female,San Jose,CA"};
how to extract each user record and sort them according to age using comparable interface?

First Thing you have to convert your string array to list.
String[] users = { "Lola,Grimsdyke,89,lgrimsdyke0#facebook.com,Female,Newport Beach,CA",
"Sybilla,Martinetto,84,smartinetto1#google.it,Female,Anniston,AL",
"Casi,Roizn,78,croizn2#scribd.com,Female,San Jose,CA" };
ArrayList<UserDetails> list=new ArrayList<>();
for (int i = 0; i < users.length; i++) {
String[] sp = users[i].split(",");
list.add(new UserDetails(sp[0], sp[1], Integer.parseInt(sp[2]), sp[3], sp[4], sp[05]));
}
for(UserDetails detail:list) {
System.out.println(detail);
}
class UserDetails {
String firstName;
String lastName;
int age;
String emailId;
String sex;
String address;
public UserDetails(String firstName, String lastName, int age, String emailId, String sex, String address) {
super();
this.firstName = firstName;
this.lastName = lastName;
this.age = age;
this.emailId = emailId;
this.sex = sex;
this.address = address;
}
#Override
public String toString() {
return "UserDetails [firstName=" + firstName + ", lastName=" + lastName + ", age=" + age + ", emailId="
+ emailId + ", sex=" + sex + ", address=" + address + "]";
}
}
After that create agecomparator to compare age.
class AgeComparator implements Comparator<UserDetails> {
#Override
public int compare(UserDetails o1, UserDetails o2) {
return o1.age - o2.age;
}
}
After that sort using comparator.
System.out.println("After Sort");
AgeComparator ageComparator=new AgeComparator();
Collections.sort(list, ageComparator);
for(UserDetails detail:list) {
System.out.println(detail);
}

Create method to count occurrences of type char within an array

I need to create a method that searches a String array whether a specfic character exists in the array and returns an integer of the number of occurrences the character appears, I have looked on other posts to try and work it out myself but they are all arrays of int not String
I have another class name hence the array name being type Name.
public class Reg {
//Fields
private ArrayList<Name> Name;
//Constructors
public Reg() {
Name = new ArrayList<>();
}
//Methods
public int CountCharacterOccurrences (Char character){
}
}
Name Class:
public class Name implements Comparable<Name> {
//Fields
private String firstName;
private String familyName;
//Constructors
public Name() {
firstName = "";
familyName = "";
}
public Name(String firstName, String familyName) {
this.firstName = firstName;
this.familyName = familyName;
}
//Methods
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public void setFamilyName(String familyName) {
this.familyName = familyName;
}
public String getFirstName() {
return firstName;
}
public String getFamilyName() {
return familyName;
}
public String getFullName() {
if (firstName.equals("") && familyName.equals("")) {
return "";
} else {
return firstName + " " + familyName;
}
}
#Override
public String toString() {
return "Name:[firstName=" + firstName + ", familyName=" + familyName + "]";
}
}
How do I add a method CountCharacterOccurences that accepts a char argument and returns an int signalling the number of occurrences.

Maybe this is what you mean:
class Reg{
private ArrayList<Name> names;
public Reg() {
names = new ArrayList<>();
}
public int countFirstNameOccurrences(char c) {
return names.stream() // get Stream<Name>
.map(Name::getFirstName) // convert Stream<Name> to Stream<String> using Name's firstName
.mapToInt(s -> s.length() - s.replace(String.valueOf(c), "").length()) // calculate every occurrence c in each firstName and get an IntStream
.sum(); // sum all the values
}
public static void main(String[] args) {
Reg reg = new Reg();
reg.names.add(new Name("John", "Doe"));
reg.names.add(new Name("Johnny ", "Doe"));
reg.names.add(new Name("Richard", "Roe"));
reg.names.add(new Name("James", "Roe"));
reg.names.add(new Name("Jane", "Roe"));
System.out.println(reg.countFirstNameOccurrences('J'));
}
}
Output:
4
as there are 4 J's in the first names in the list (John, Johnny, James and Jane)

two person object

import cs1.Keyboard;
import java.util.Scanner;
class Person
{
private String name;
private String persnr;
private String adress;
private int age;
public Person(String _name, String _persnr, String _adress, int _age)
{
name = name;
persnr = persnr;
adress = adress;
age = age;
}
public void byterNamn(String _name)
{
name = _name;
}
public void byterAdress(String _adress)
{
adress = _adress;
}
public void fyllerAr()
{
age = age + 1;
}
public String hamtaNamn()
{
return name;
}
public String hamtaPersonnmmer()
{
return persnr;
}
public String hamtaAdress()
{
return adress;
}
public int hamtaAlder()
{
return age;
}
public String toString()
{
String _toString;
_toString = "Namn: " + name + "\nÅlder: " + age;
_toString = _toString + "\nPersonnummer: " + persnr + "\nAdress: " + adress;
return _toString;
}
public p1()
{
System.out.print("namn: ");
name = Keyboard.readString();
System.out.print( "adress: " );
String adress = Keyboard.readString();
System.out.print( "ålder: " );
Integer age = new Integer();
age.parseInt(Keyboard.readint());
System.out.print( "personnummer: " );
String persnr = Keyboard.readString();
}
public p2()
{
System.out.print("namn: ");
name = Keyboard.readString();
System.out.print( "adress: " );
String adress = Keyboard.readString();
System.out.print( "ålder: " );
Integer age = new Integer();
age.parseInt(Keyboard.readint());
System.out.print( "personnummer: " );
String persnr = Keyboard.readString();
}
public static void main(String[] args)
{
String name = Keyboard.readString();
String persnr = Keyboard.readString();
String adress = Keyboard.readString();
int age = Keyboard.readint();
Person p1 = new Person(name, age, adress, personnummer);
String name = Keyboard.readString();
String persnr = Keyboard.readString();
String adress = Keyboard.readString();
int age = Keyboard.readint();
Person p2 = new Person(name, age, adress, personnummer);
}
}
hello.
I try to do so it is 2 people. where you should enter the age, name, address of both people and then print it after you enter what you want when the program runs. and i wondering how do i do return on public p1() and public p2() so i can do it. Or is it a easier way to do it?

This code does not compile. public p1() and public p2() are not valid method declarations. You must at least add a method return type after the public and before the method name, for example:
public Person p1()
Then I guess what you want to do is return a Person object from each of those two methods. Inside the method you must create a new Person object and then return it from the method:
return new Person(name, persnr, adress, age);
See Defining Methods and Returning a Value from a Method in Oracle's Java Tutorials.