I'm working on a project that involves three code files: a class for passengers - Passenger.java, a class for the airplane itself - Airplane.java, and a driver class - RunAirplane.java. 5 passengers have been added using the Passenger instantiation in main along with a count of the passengers that I plan on updating later so it is not limited to 5. The issue is that I keep getting a NullPointerException error whenever I run the main file in IntelliJ and cant find out why. The error code says it's happening on line 58 of the Airplane.java file which leads me to assume that it's because of the addPassenger method.
Passenger Class (if needed)
public class Passenger {
private String name;
private int birthYear;
private double weight;
private char gender;
private int numCarryOn;
//Default constructor
public Passenger(){
name = "";
birthYear = 1900;
weight = 0.0;
gender = 'u';
numCarryOn = 0;
}
//Alt default constructor
public Passenger(String newName, int newBirthYear, double newWeight, char newGend, int newNumCarryOn){
this.setName(newName);
this.setBirthYear(newBirthYear);
this.setWeight(newWeight);
this.setGender(newGend);
this.setNumCarryOn(newNumCarryOn);
}
//Calculate age
public int calculateAge(int currentYear){
int age = 0;
if (currentYear < birthYear){
return -1;
}
else {
age = currentYear - birthYear;
}
return age;
}
//Gain weight
public void gainWeight(){
weight += 1;
}
//Gain weight based on input
public void gainWeight(double pounds){
if (weight > 0){
weight = weight + pounds;
}
}
//Get birthYear
public int getBirthYear(){
return birthYear;
}
//Get gender
public char getGender(){
return gender;
}
//Get name
public String getName(){
return name;
}
//Get weight
public double getWeight(){
return weight;
}
//Get numCarryOn
public int getNumCarryOn(){
return numCarryOn;
}
//isFemale
public boolean isFemale(){
if (gender == 'f'){
return true;
}
else {
return false;
}
}
//isMale
public boolean isMale(){
if (gender == 'm'){
return true;
}
else {
return false;
}
}
//loseWeight
public void loseWeight(){
if (weight > 0){
weight -= 1;
}
}
//lose weight by value
public void loseWeight(double weight2lose){
if (weight - weight2lose >= 0){
weight -= weight2lose;
}
}
//print
public void printDetails(){
System.out.printf("Name: %20s | Year of Birth: %4d | Weight: %10.2f | Gender: %c | NumCarryOn: %2d\n", name, birthYear, weight, gender, numCarryOn);
}
//setGender
public void setGender(char newGender){
if (newGender == 'f' || newGender == 'm') {
this.gender = newGender;
} else {
this.gender = 'u';
}
}
//setName
public void setName(String newName){
name = newName;
}
//setBirthYear
public void setBirthYear(int newBY){
birthYear = newBY;
}
//setWeight
public void setWeight(double newWeight){
if (newWeight < 0){
weight = -1;
}
else {
weight = newWeight;
}
}
//setNumCarryOn
public void setNumCarryOn(int newNumCarryOn){
if (newNumCarryOn < 0){
numCarryOn = 0;
}
else if (newNumCarryOn > 2){
numCarryOn = 2;
}
else {
numCarryOn = newNumCarryOn;
}
}
}
Airplane Class
import java.util.Arrays;
public class Airplane {
private Passenger[] passengers;
private String airplaneName;
private int numPassengers;
public int count = 0;
//default constructor
public Airplane(){
airplaneName = "";
passengers = new Passenger[100];
numPassengers = 0;
}
//default constructor with String input
public Airplane(String otherairplaneName){
airplaneName = otherairplaneName;
passengers = new Passenger[100];
numPassengers = 0;
}
//default constructor with int input
public Airplane(int otherArraySize){
airplaneName = "";
if (otherArraySize < 0){
otherArraySize = 0;
passengers = new Passenger[otherArraySize];
}
numPassengers = 0;
}
//default constructor with String and int input
public Airplane(String otherAirplaneName, int otherArraySize){
airplaneName = otherAirplaneName;
if (otherArraySize < 0){
otherArraySize = 0;
passengers = new Passenger[otherArraySize];
}
numPassengers = 0;
}
//add a passenger
public void addPassenger(Passenger a){
for (int i = 0; i < passengers.length; i++){
if (passengers.length - count >= 0){
passengers[i] = a;
break;
}
}
}
}
Driver
public class RunAirplane {
public static void main(String[] args) {
Airplane a1 = new Airplane("Flight 1", 100);
Passenger p1 = new Passenger("Albert", 1879, 198.5, 'm', 2);
Passenger p2 = new Passenger("Grace", 1906, 105, 'f', 1);
Passenger p3 = new Passenger("Tim", 1955, 216.3, 'm', 2);
Passenger p4 = new Passenger("Steve", 1955, 160, 'm', 2);
Passenger p5 = new Passenger("Sergey", 1973, 165.35, 'm', 1);
a1.addPassenger(p1);
a1.count += 1;
a1.addPassenger(p2);
a1.count += 1;
a1.addPassenger(p3);
a1.count += 1;
a1.addPassenger(p4);
a1.count += 1;
a1.addPassenger(p5);
a1.count += 1;
a1.printAllDetails();
}
}
