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Problem filling an array of objects. The result is always null

I created a three-class program. In the third class, I should fill the array with the values "name", "surname", "code", and "age". What happens though is that my array is always "null", and I can't fill it. Thank you all for your help.
First class:
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
String name, surname;
int code, age, i=0, min=150;
System.out.println("How many teachers do you want to enter information?");
i=in.nextInt();
for(int j=0; j<i; j++)
{
System.out.println("Enter the teacher's name");
name=in.next();
System.out.println("Enter the teacher's surname");
surname=in.next();
System.out.println("Enter the teacher's code");
code=in.nextInt();
System.out.println("Enter the teacher's age");
age=in.nextInt();
Teacher d = new Teacher(name, surname, code, age);
System.out.println(d.getCode());
System.out.println(d.getSurname());
System.out.println(d.getAge());
University c = new University(name, surname, code, age);
min=c.MinimumAge(age, min);
}
System.out.println(min);
}
}
Second class:
public class Teacher
{
protected String name;
protected String surname;
protected int code;
protected int age;
public Teacher(String name, String surname, int code, int age)
{
this.name=name;
this.surname=surname;
this.code=code;
this.age=age;
}
public String getName()
{
return name;
}
public int getCode()
{
return code;
}
public String getSurname()
{
return surname;
}
public int getAge()
{
return age;
}
}
Third class (I put "0" as a location for filling the array just to do tests.):
public class University
{
private Teacher[] array=new Teacher[4];;
public University(String name, String surname, int code, int age)
{
array[0] = new Teacher(name, surname, code, age);
}
public int MinimumAge(int age, int min)
{
if (age<min)
min=age;
return min;
}
}

The class University has not been implemented correctly. You can implement it as:
class University {
private int counter = 0;
private final int MAX = 4;
private Teacher[] array = new Teacher[MAX];
public void addTeacher(Teacher teacher) {
if (counter < MAX) {
array[counter++] = teacher;
}
}
public int minimumAge() {
if (counter == 0) {
return 0;
}
int min = array[0].getAge();
for (int i = 1; i < counter; i++) {
if (array[i].getAge() < min) {
min = array[i].getAge();
}
}
return min;
}
}
Accordingly, you need to change your code in main as shown below:
public class Main {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
String name, surname;
int code, age, i = 0, min = 150;
University university = new University();
System.out.print("How many teachers do you want to enter information?: ");
i = in.nextInt();
for (int j = 0; j < i; j++) {
System.out.print("Enter the teacher's name: ");
name = in.next();
System.out.print("Enter the teacher's surname: ");
surname = in.next();
System.out.print("Enter the teacher's code: ");
code = in.nextInt();
System.out.print("Enter the teacher's age: ");
age = in.nextInt();
university.addTeacher(new Teacher(name, surname, code, age));
}
System.out.println(university.minimumAge());
}
}
A sample run:
How many teachers do you want to enter information?: 2
Enter the teacher's name: a
Enter the teacher's surname: b
Enter the teacher's code: 1
Enter the teacher's age: 23
Enter the teacher's name: x
Enter the teacher's surname: y
Enter the teacher's code: 2
Enter the teacher's age: 15
15

Using toString() method in Java

I am trying to utilize the toString() in a class I have called Employee(). I have a 1D array of type Employee, which stores Employee Data, which include the Employee ID, Employee Name, Employee Address, and Employee Hire Date. I want the user to specify the amount of employees, and then enter the relevant data for however many employees the user wants. I then want to print the result for the user with the information entered. I keep getting some results that are null. I tried using an If statement that printed output if it didn't equal null, but that didn't work. I know the output works if I print out a single variable, such as address, but I want all variables to print out. Thank you for any help.
public class Address
{
public String address;
public void getAddress(String a)
{
address = a;
}
public String toString()
{
return address;
}
}
public class Name
{
String name;
public void getName(String n)
{
name = n;
}
public String toString()
{
return name;
}
}
public class Date
{
public String date;
public String date1;
public void getDate(int d, int m, int y)
{
date1 = (m + "/" + d + "/" + y);
}
public String toString()
{
return date1;
}
}
import java.util.Scanner;
public class Employee
{
private int number;
private Name name1 = new Name();
private Address address1 = new Address();
private Date hireDate = new Date();
String number1;
public void getDate1(int d, int m, int y)
{
hireDate.getDate(d, m, y);
}
public void getID(int x)
{
number = x;
}
public void setName( String n)
{
name1.getName(n);
}
public void getAddress(String a)
{
address1.address = a;
}
String z;
public String toString()
{
number1 = String.valueOf(number);
String name2 = String.valueOf(name1);
String address2 = String.valueOf(address1);
String hireDate2 = String.valueOf(hireDate);
z = number1 + " " + name2 + " " + address2 + " " + hireDate2;
return z;
}
public static void main(String args[])
{
Scanner input = new Scanner(System.in);
System.out.println("Please enter amount of Employees: ");
int input1 = input.nextInt();
input.nextLine();
for (int i = 0; i < input1; i++)
{
Employee [] employees = new Employee[4];
System.out.println("Please enter the employee ID: ");
int employeeID = input.nextInt();
input.nextLine();
employees[0] = new Employee();
employees[0].getID(employeeID);
System.out.println("Please enter the employees Name: ");
String name2 = input.nextLine();
employees[1] = new Employee();
employees[1].setName(name2);
System.out.println("Please enter the employee's address: ");
String address2 = input.nextLine();
employees[2] = new Employee();
employees[2].getAddress(address2);
System.out.println("please enter hire date, day (1-31),");
System.out.print("month (1-12), year (1901 - 2019) in order on seperate");
System.out.print(" lines: ");
int input2 = input.nextInt();
int input3 = input.nextInt();
int input4 = input.nextInt();
employees[3] = new Employee();
employees[3].getDate1(input2, input3, input4);
for (int p = 0; p < employees.length; p++)
{
System.out.println(employees[p]);
}
}
}
}

I have create classes which were needed. You can change them but you are creating employee object every time. I have corrected the code debug it and you will know what was wrong.
import java.util.Calendar;
import java.util.Date;
import java.util.Scanner;
class Name {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
class Address {
private String address;
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
}
public class Employee {
private int number;
private Name name1 = new Name();
private Address address1 = new Address();
private Date hireDate = new Date();
String number1;
public void getDate1(int d, int m, int y) {
Calendar calendar = Calendar.getInstance();
calendar.set(y, m, d);
hireDate = calendar.getTime();
}
public void getID(int x) {
number = x;
}
public void setName(String n) {
name1.setName(n);
}
public void getAddress(String a) {
address1.setAddress(a);
}
String z;
public String toString() {
number1 = String.valueOf(number);
String name2 = name1.getName();
String address2 = address1.getAddress();
String hireDate2 = String.valueOf(hireDate);
z = number1 + " " + name2 + " " + address2 + " " + hireDate2;
return z;
}
public static void main(String args[]) {
Scanner input = new Scanner(System.in);
System.out.println("Please enter amount of Employees: ");
int input1 = input.nextInt();
input.nextLine();
Employee[] employees = new Employee[input1];
for (int i = 0; i < input1; i++) {
System.out.println("Please enter the employee ID: ");
int employeeID = input.nextInt();
input.nextLine();
employees[i] = new Employee();
employees[i].getID(employeeID);
System.out.println("Please enter the employees Name: ");
String name2 = input.nextLine();
employees[i].setName(name2);
System.out.println("Please enter the employee's address: ");
String address2 = input.nextLine();
employees[i].getAddress(address2);
System.out.println("please enter hire date, day (1-31),");
System.out.print("month (1-12), year (1901 - 2019) in order on seperate");
System.out.print(" lines: ");
int input2 = input.nextInt();
int input3 = input.nextInt();
int input4 = input.nextInt();
employees[i].getDate1(input2, input3, input4);
System.out.println(employees[i]);
}
}
}

Java Address Book String Reading

I have been having trouble with my removeContact method in the AddressBook class. I can get it to work when I enter a first name, but for some reason can't get it to work for the full name. This is probably simple but i'm just getting nowhere. Thanks
AddessBook Class
public class AddressBook {
private Contact contacts[] = new Contact[100]; //Array to hold all the contacts
private int count = 0; //Number of contacts in the array(in address book)
private String fileName;
AddressBook(String fileName){
this.fileName = fileName;
}
//Add Contact
public boolean addContact(Contact contact){
if(count<100){
contacts[count] = contact;
count++;
return true;
}else{
return false;
}
}
//Remove Contact
public boolean removeContact(String fullname){
for(int i = 0; i<count; i++){
if(fullname.equals(contacts[i].getFullName())){
for(int j = i; j<count; j++){
contacts[j] = contacts[j+1];
}
count--;
}else{
return false;
}
}
return true;
}
//Search Contact
//Display Contacts
public void displayContacts(){
for(int i = 0; i<count; i++){
System.out.println(contacts[i]);
}
}
}
Contact Class
public class Contact {
private String firstName;
private String lastName;
private String phone;
//Contact constructor
Contact(String firstName, String lastName, String phone){
this.firstName = firstName;
this.lastName = lastName;
this.phone = phone;
}
//First name getter
public String getFirstName(){
return firstName;
}
//Last name getter
public String getLastName(){
return lastName;
}
//Full name getter
public String getFullName(){
return firstName+" "+lastName;
}
//Phone number getter
public String getPhone(){
return phone;
}
//First name mutator
public void setFirstName(String firstName){
this.firstName = firstName;
}
//Last name mutator
public void setLastName(String lastName){
this.lastName = lastName;
}
//Phone number mutator
public void setPhone(String phone){
this.phone = phone;
}
//Method to compare first and last names for similarity
public boolean compare(Object o){
Contact contact = (Contact) o;
if(firstName == contact.firstName && lastName == contact.lastName){
return false;
}else{
return true;
}
}
public String toString(){
return firstName+" "+lastName+" "+phone;
}
}
Main Class
import java.util.*;
public class Main {
public static void main(String [] args){
AddressBook addressbook = new AddressBook("Info.txt");
Scanner s = new Scanner(System.in);
boolean quit = false;
while(!quit){
System.out.println("What would you like to do?");
System.out.println(" 1) Display all contacts");
System.out.println(" 2) Add a contact");
System.out.println(" 3) Remove a contact");
System.out.println(" 4) Search a contact");
System.out.println(" 5) Exit");
switch(s.nextInt()){
case 1:
addressbook.displayContacts();
break;
case 2:
System.out.println("First Name: ");
String fName = s.next();
System.out.println("Last Name: ");
String lName = s.next();
System.out.println("Phone Number: ");
String pNumber = s.next();
addressbook.addContact(new Contact(fName, lName, pNumber));
break;
case 3:
System.out.println("Enter in full name: ");
String fullname = s.next();
addressbook.removeContact(fullname);
break;
case 4:
System.out.println("Enter the name of the contact you are looking for: ");
case 5:
quit = true;
break;
}}}}

You are asking for the full name and then comparing it only with the first name:
if(fullname.equals(contacts[i].getFirstName())){
Just compare it with the full name...

When you make your call to the "removeContact" method, you are passing as parameter only the name, not the last name; let say you create the contact "John Doe". When you search for "John Doe" you pass "John" as the name to the method but "Doe" is the next token in the scanner, so when you try to do s.nextInt() you have a problem because "Doe" is not an int.
Also, your removeContact method is not gonna work when you have more than 1 contact. You are doing a return if the first contact of the address book is not the one you are looking for.
Edit:
Try this and let me know what happens:
case 3:
System.out.println("Enter in full name: ");
String firstName = s.next();
String lastName = s.next();
addressbook.removeContact(firstName + " " + lastName);
break;
Edit 2:
// Remove Contact
public boolean removeContact(String fullname) {
for (int i = 0; i < count; i++) {
// No need for an else here
if (fullname.equals(contacts[i].getFullName())) {
for (int j = i; j < count; j++) {
contacts[j] = contacts[j + 1];
}
count--;
return true;
}
}
return false;
}

Ok, I ran your code and tried to remove a name , so I got this error :
Exception in thread "main" java.util.InputMismatchException
Your remove method is not correct. You can easily have 17 Bob's in your Address Book - "Bob Smith", "Bob Jacobs", "Bob Ahmed" , whatever...
You need to fix the removeContact method to look more like this :
public boolean removeContact(String fname, String lname){
for(int i = 0; i<count; i++){
if(contacts[i].getFirstName().equals(fname) && contacts[i].getLastName().equals(lname)){
for(int j = i; j<count; j++){
contacts[j] = contacts[j+1];
}
Also, the case 3 of Main should lok like this :
case 3:
System.out.println("Enter in first name: ");
String firstname = s.next();
System.out.println("Enter in last name: ");
String lastname = s.next();
addressbook.removeContact(firstname, lastname);
break;

Java can't get array list to print out?

So i have 3 classes, and one that runs all the code. A student class, a Graduate student class and an undergraduate class, and a class called lab 4 that runs the code. The code asks for how many grad students and how many undergrad students there are, then asks the user to input all the information for that number of each. After all the info is inputed, the under grad or grad student objects are added to an array list of students. after all the students are added, then prints all the information. However when i input all the information, the array does not print, the program terminates. How do i get the array to print out?
Code:
Lab 4: creates the student objects, array list, adds them to the array, and the prints all information for objects added to the array list
import java.util.ArrayList;
import java.util.Scanner;
public class Lab04 {
public static void main(String[] args) {
ArrayList <Student> studentList = new ArrayList <Student>();
Scanner s = new Scanner(System.in);
System.out.println("How many Graduate Students do you want to store?");
int numOfStudents = s.nextInt();
s.nextLine();
for (int i = 0; i < numOfStudents; i++) {
System.out.println("What is the student's name?");
String name = s.nextLine();
System.out.println("What is the student's GPA?");
double GPA = s.nextDouble();
s.nextLine();
System.out.println("What is the student's ID?");
String ID = s.nextLine();
System.out.println("What is the student's High School?");
String highSchool = s.nextLine();
System.out.println("What is the student's graduate major?");
String gradMajor = s.nextLine();
System.out.println("What is the student's undergraduate major?");
String underMajor = s.nextLine();
System.out.println("What is the student's undergradute school? ");
String underSchool = s.nextLine();
GraduateStudent gradStu = new GraduateStudent(name, GPA, ID, highSchool, gradMajor, underMajor,
underSchool);
studentList.add(gradStu);
}
System.out.println("How many UnderGraduate students are there?");
int numOfUnder = s.nextInt();
s.nextLine();
for (int j = 0; j < numOfUnder; j++) {
System.out.println("What is the student's name?");
String name = s.nextLine();
System.out.println("What is the student's GPA?");
double GPA = s.nextDouble();
s.nextLine();
System.out.println("What is the student's ID?");
String ID = s.nextLine();
System.out.println("What is the student's High School?");
String highSchool = s.nextLine();
System.out.println("What is the student's major?");
String major = s.nextLine();
System.out.println("What the student's minor?");
String minor = s.nextLine();
UnderGraduate UnderGrad = new UnderGraduate(name, GPA, ID, highSchool, major, minor);
studentList.add(UnderGrad);
}
for (int j = 0; j < studentList.size(); j++) {
(studentList.get(j)).getStudentInformation();
}
}
}
Student Class:
public class Student {
private String name;
private double gpa;
private String id;
private String highSchool;
//private String major;
//private String minor;
public Student() {
name = "";
gpa = 0.0;
id = "";
highSchool = "";
//major = "";
//minor = "";
}
public Student(String name, double gpa, String id, String highSchool){
this.name = name;
this.gpa = gpa;
this.id = id;
this.highSchool = highSchool;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public double getGpa() {
return gpa;
}
public void setGpa(double gpa) {
this.gpa = gpa;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getHighSchool() {
return highSchool;
}
public void setHighSchool(String highSchool) {
this.highSchool = highSchool;
}
public String getStudentInformation() {
String result = "Name: " + name + " GPA: " + gpa + " ID: " + id
+ " High School: " + highSchool;
return result;
}
}
graduate Class:
public class GraduateStudent extends Student {
private String gradMajor;
private String underMajor;
private String underSchool;
public GraduateStudent(String name, double gpa, String id, String highSchool,
String gradMajor, String underMajor, String underSchool) {
super(name, gpa, id, highSchool);
this.gradMajor = gradMajor;
this.underMajor = underMajor;
this.underSchool = underSchool;
}
public String getGradMajor() {
return gradMajor;
}
public void setGradMajor(String gradMajor) {
this.gradMajor = gradMajor;
}
public String getUnderMajor() {
return underMajor;
}
public void setUnderMajor(String underMajor) {
this.underMajor = underMajor;
}
public String getUnderSchool() {
return underSchool;
}
public void setUnderSchool(String underSchool) {
this.underSchool = underSchool;
}
#Override
public String getStudentInformation() {
String result = super.getStudentInformation()+
"Graduate Major: " + gradMajor + "Undergraduate Major: " + underMajor +
"Undergraduate School: " + underSchool;
return result;
}
}

Because you're not printing anything. Change
for (int j = 0; j < studentList.size(); j++) {
(studentList.get(j)).getStudentInformation();
}
to
for (int j = 0; j < studentList.size(); j++) {
System.out.println((studentList.get(j)).getStudentInformation());
}

When you ask getStudentInformation, it returns a String, what you want to do now is to System.out.println(...) this String object

ArrayList Object

I am using the ArrayList Object to create an employee object of type employee...I implement the class and it seems to work, but my problem is that when I insert the employees into the ArrayList it is automatically doesn't insert it. Why is that?
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
/**
*
* #author
*/
import java.util.*;
class Employee {
private String fname;
private String lname;
public Employee (String fname, String lname){
this.fname = fname;
this.lname = lname;
}
public Employee (){
}
public String getLastName(){
return this.lname;
}
public void setLastName(String lname){
this.lname = lname;
}
public String getFirstName(){
return this.fname;
}
public void setFirstName (String fname){
this.fname = fname;
}
public String toString(){
return this.getClass().getName() +" [ "
+ this.fname + " "
+ this.lname + " ]\n ";
}
public Object clone(){ //Object is used as a template
Employee emp;
emp = new Employee(this.fname, this.lname);
return emp;
}
}
//start of main
public class main
{
static Scanner input = new Scanner(System.in);
public static final int MAX_EMPLOYEES = 10;
public static void main(String[] args) {
String fname, lname;
int num;
System.out.print("Enter the number of employees in your system: ");
num = input.nextInt();
ArrayList<Employee> emp = new ArrayList<Employee>(num);
System.out.print("Enter the first name: ");
fname = input.next();
System.out.println();
System.out.print("Enter the last name: ");
lname = input.next();
System.out.println();
for (int x = 1; x < num; x++)
{
System.out.print("Enter the first name: ");
fname = input.next();
System.out.println();
System.out.print("Enter the last name: ");
lname = input.next();
System.out.println();
emp.add(new Employee(fname,lname));
}
num = emp.size();
System.out.println(num);
System.out.println(emp);
}
}

Add:
emp.add(new Employee(fname,lname));
just before your for loop or rewrite your for loop conditional as:
for (int x = 0; x < num; x++)
and get rid of the
System.out.print("Enter the first name: ");
fname = input.next();
System.out.println();
System.out.print("Enter the last name: ");
lname = input.next();
System.out.println();
before the for loop.

Your loop is running 1 less time than is required.
for(int i=0;i<num; i++){
This should fix it.