public class Pig {
private int pigss;
private Pig[] pigs;
public Pig[] pigNumber (int pigss)
{
pigs = new Pig [pigss];
return pigs;
}
Code that includes main method:
public class animals{
public static void main(String[] args){
Pig cool = new Pig();
Scanner keyboard = new Scanner (System.in);
System.out.println("How many pigs are there?");
int pigss = Integer.parseInt( keyboard.nextLine() );
cool.pigNumber(pigss);
//This is where I have trouble. I want to use the array pigs here in the main method, this is what i tried:
Pig[] pigs = cool.pigNumber(pigss);
I then tried to use a for loop and assign values (String) to the index of arrays (pigs[]). But the error that gives me is: cannot convert from String to Pig. Any tips are appreciated. THank you.
for(int j = 0; j < pigs.length; j++)
{
System.out.println("What is the pig " + (j+1) + "'s name");
pigs[j] = keyboard.nextLine();
}
Your pigs will need an attribute to contain the string values you are trying to pass:
public class Pig {
private String name;
public void setName(String n) {
name = n;
}
public String getName() {
return name;
}
Then when you want to assign this string value to your pig:
int indexOfPig = 0; // Or whatever it is supposed to be
pigs[indexOfPig].setName("I am a string");
In java you can only use ints as the indexes of arrays
It is saying 'cannot convert from String to Pig' because you can't do that!
If you want somehow convert a String to a Pig, you are going to need to write some code to do the conversion. For example, you might write a constructor that creates a new Pig from some kind of description. Or you might write a method that looks up a Pig by name or number or something.
It is hard to offer any more concrete advice because you don't tell us what is in the string values ... or how you expect the strings to become pigs. (The only suggestion I have is to try Macrame :-) )
Pig doesn't have a name member or even method that accepts a string. Also you are trying to assign a String(keyboard.nextline() to a Pig(pigs[j].
Add an attribute name to your pig.
class Pig{
public String name:
public void Pig(String name){
this.name = name;
}
}
Then assign a new instance of Pig in the loop.
pigs[j] = new Pig(keyboard.nextLine());
Also get rid of the useless class pigNumber. All you need is an ArrayList of Pigs. The array list can be dynanically sized.
List<Pig> pigs = new ArrayList<Pig>
so your loop could be something like
String name = ""
while(true){
name = keyboard.readline();
if(name== "stop"){
break;
}
pigs.add(new Pig(names);
}
Then getting the number of pigs is a simple
System.out.println(pigs.length());
Related
This question already has answers here:
Is it possible in Java to access private fields via reflection [duplicate]
(3 answers)
Closed 7 years ago.
My template opens with a menu of options and the user inputs something between 1-3 to select one of the three options.
When the user chooses option 1, it asks them to input a number teamNumber. One must instantiate the class Team, then it writes it to an arraylist.
If there is at least one number in numberList, the user can select option 2. It asks them to input any of the numbers from the arraylist and searches it. If the number they input is found, then you input a String teamMemberFirstName and a char firstInitialLastName. Then it will write the input to a private arraylist located in another class TeamMember.
Once they have input the info in option 1 and 2, they can choose option 3. It allows you to print the list of inputted names based on which team number you put them on.
I am not sure how, in option 3, to call the private arraylist from the TeamMember class teamList. Any guidance on how to proceed with this step? My code is below.
Main class:
public class Main {
public static void main(String[] args) {
int choosing;
Scanner scan = new Scanner(System.in);
String input;
int teamNumber;
boolean stayInLoop;
ArrayList<Team> numberList = new ArrayList<Team>();
do {
stayInLoop = true;
System.out.println("1. Add a new team");
System.out.println("2. Add a new team member");
System.out.println("3. View teams");
input = scan.nextLine();
if (input.equals("1")) {
System.out.println("Enter a team number:");
teamNumber = scan.nextInt();
scan.nextLine();
Team addTeam = new Team(teamNumber);
numberList.add(addTeam);
}
if (input.equals("2")){
boolean foundIt = false;
boolean valid = true;
System.out.println("Team number:");
teamNumber = scan.nextInt();
scan.nextLine();
for (int a = 0; a < numberList.size() && foundIt == false; a++){
Team addTeam = numberList.get(a);
if (addTeam.findTeam() == teamNumber) {
foundIt = true;
System.out.println("Enter first name of team member:");
String teamMemberFirstName = scan.nextLine();
System.out.println("Enter first initial of last name:");
char firstInitialLastName = scan.nextLine().charAt(0);
TeamMember inputTeamMember = new TeamMember(teamMemberFirstName, firstInitialLastName);
inputTeamMember.addMember(inputTeamMember, valid = true);
System.out.println("Success!");
}
}
if (foundIt == false) {
System.out.println("Try again.");
}
}
if (input.equals("3")){
for (int a = 0; a < numberList.size(); a++) {
Team addTeam = numberList.get(a);
//Not sure what to put where there are ????'s - I tried a few ideas and stuff I found online, but nothing worked
//I assume I call the method/class here????
System.out.println("Team: " + addTeam.findTeam() + " Members: " +
"I will put the member called from the arraylist here????");
}
}
}while (stayInLoop == true;)
}}
TeamMember class:
public class TeamMember {
private final String teamMemberFirstName;
private final char firstInitialLastName;
private ArrayList<TeamMember> teamList = new ArrayList<>();
public TeamMember(String teamMemberFirstName, char firstInitialLastName) {
this.teamMemberFirstName = teamMemberFirstName;
this.firstInitialLastName = firstInitialLastName;
}
public int addMember(TeamMember member, boolean valid) {
valid = teamList.add(member);
return teamList.size();
}
}
You cannot directly access private fields from other classes. Either move your list to the Team class or create a getter to retrieve the list.
In a public class, you can return a private object in a public method. This seems like the easiest way in this project. Add a new method to your TeamMember class, and have it return teamList:
//inside your TeamMember class, anywhere after you assign the private variable
public static ArrayList show(){
//the static keyword, in short, will make the method callable without a class instance.
return teamList;
}
Since the TeamMember method show() is now static, you should be able to simply call TeamMember.show() and get the ArrayList.
Important note: In order for this to work, you must make the private arraylist static too. A static object cannot call a non-static object.
This will turn it into private static ArrayList<TeamMember> teamList = new ArrayList<>();
In the Main class, like I said above, simply call TeamMember.show(). You do not need to create an instance.
If you change your teamList to public instead of private your Main class will be able to access the variable. When you make something private in Java you're basically making that instance variable accessible only through the class that it's instantiated in. If you want the variable to be visible to other classes for reference you should make it public
Since the assignment calls for it, you're going to need to define a getter and setter for your 'teamList' variable.
public void setArray(ArrayList newTeamList){
teamList = newTeamList;
}
public ArrayList getArray(){
return teamList;
}
This'll allow you to access the private variable through the methods
What I have below is producing the desired results by print some employee details along with weekly / monthly wages as appropriate.
However I understand that I should not be inputting data in the constructor as I've done.
I need to prompt for a hours worked value only for "PartTimeEmployees", just not the way I've done it.
I've tested with For-Each loops, Enhanced For loops and using the instanceOf operator.
If I could get some guidance/hints or examples of how to accomplish what is currently being done in the constructor, but in the TestEmployee class instead that would be great.
Mostly I'm not sure how to even describe what I'm trying to achieve. This hinders Googling somewhat. (Help with a better title would also be great)
Thanks in advance.
public class TestEmployee
{
public static void main(String[] args)
{
int size;
Employee[] employees = new Employee[4];
employees[0] = new FullTimeEmployee("Jane", 26000);
employees[1] = new PartTimeEmployee("Jack");
employees[2] = new FullTimeEmployee("Lucy", 52000);
employees[3] = new PartTimeEmployee("Lenny");
for(int i = 0; i < employees.length; i++)
{
employees[i].print();
}
}
}
Class: PartTimeEmployee - Constructor:
public PartTimeEmployee(String thisName)
{
super(thisName);
System.out.println("Please enter the number of hours worked by " + thisName + ": ");
numHours = keyboard.nextInt();
setHours(numHours);
}
If I get your question, below might fit with your need -
First of all create generic Employee class -
class Employee {
private String name;
private int workingHours;
private final boolean IS_PART_TIME_EMP;
public Employee(String name, int workingHours) {
this.name = name;
this.workingHours = workingHours;
this.IS_PART_TIME_EMP = false;
}
public Employee(String name) {
this.name = name;
this.IS_PART_TIME_EMP = true;
}
public String getName() {
return name;
}
public int getWorkingHours() {
return workingHours;
}
public void setWorkingHours(int workingHours) {
this.workingHours = workingHours;
}
public boolean isPartTimeEmployee() {
return IS_PART_TIME_EMP;
}
}
Now you can use it as per your requirement.
Employee[] employees = new Employee[4];
employees[0] = new Employee("Jane", 26000);
employees[1] = new Employee("Jack");
employees[2] = new Employee("Lucy", 52000);
employees[3] = new Employee("Lenny");
Scanner sc = new Scanner(System.in);
for (Employee employee : employees) {
if(employee.isPartTimeEmployee()) {
System.out.println("Please enter working hours by " + employee.getName() + ": ");
int numHours = sc.nextInt();
employee.setWorkingHours(numHours);
}
}
Constructor is not meant for user input.Its main intention is to initialize object of that class.
Instead of doing that in constructor,you can try something like this
employees[1] = new PartTimeEmployee("Jack");
System.out.println("Please enter the number of hours worked by " + employees[1].getName()+ ": ");
numHours = keyboard.nextInt();
employees[1].setHours(numHours);
You most likely will have some logical main loop in your program, like
while(!quit) {
// 1. ask if you want to add part time or full time employee
// 2. ask proper questions
// 3. call correct constructor
}
Writing such small pseudo code algorithm should be self explanatory and get you going.
Step one: presentation of options available for user and reading user input.
Step two: performing actions depending on user input from step 1
Step three: final call to proper constructor depending on results from steps 1 and 2
If I understood your question correctly (which I'm really not sure of) you want to prompt for the employee data in the main method.
In that case I'd use a loop and query the following things:
name of the employee
does the employee work full time? (y/n)
if yes: what is the wage? (assume hours = whatever a full time employee works a day)
if no: how many hours? (and probably the hourly wage as well)
Then use that information to construct an Employee object (I don't see any need for the subclasses here).
I am running into some issues with my Java program. We have to create a library, which contains the title(halo, lotr) , the format (xbox, dvd etc), the date loaned (if it is ever loaned), and the person it is loaned to (if it is ever loaned).
I am not complete with my code, however I am testing it out as I go along instead of just compiling the entire finished code after 5 hours of coding. I am running into a problem. Whenever I set a public string variable to a value, it saves in the method I declared it in, but it will display "null" when system.out.print'd in other methods.
heres my code. First class is Library.
package p1;
import java.util.Scanner;
public class Library {
// \/ FIELDS
private String[] mediaItemTitle = new String[100];
public String[] mediaItemFormat = new String[100];
public String[] mediaItemLoanedTo = new String[100];
public String[] mediaItemOnLoan = new String[100];
public String[] mediaItemDateLoaned = new String[100];
public String today = "3/9/2015";
public int numberOfItems;
// /\ FIELDS
// \/ METHODS
public static void main(String[] brad){
Scanner input = new Scanner(System.in);
MediaItem main;
main = new MediaItem();
String title;
String format;
String date;
String name;
for ( int i = 0; i != 5; ){
i = displayMenu();
if (i == 1){
System.out.println("What is the title? ");
title = input.nextLine();
System.out.println("What is the format? ");
format = input.nextLine();
main.MediaItem(title,format);
}else if (i == 2){
System.out.println("Which Item (Enter the title? ");
title = input.nextLine();
System.out.println("Who are you loaning it to? ");
name = input.nextLine();
System.out.println("When did you loan it to them? ");
date = input.nextLine();
}else if (i == 3){
main.MediaItem();
}else if (i == 4){
System.out.print("Which item? (enter the title) ");
title = input.nextLine();
main.markReturned(title);
}else if (i == 5){ // DONE
System.out.print("Goodbye!");
break;
}
}
}
public static int displayMenu(){ // DONE
Scanner input = new Scanner(System.in);
int choice = 0;
System.out.println("1. Add new item");
System.out.println("2. Mark an item as on loan");
System.out.println("3. List all items");
System.out.println("4. Mark an item as returned");
System.out.println("5. Quit");
choice = input.nextInt();
return choice;
}
public void addNewItem(String title, String format){
this.mediaItemTitle[numberOfItems] = title;
this.mediaItemFormat[numberOfItems] = format;
System.out.print("TEST: " + mediaItemTitle[numberOfItems]);
}
public void incrementNumberOfItems(){
numberOfItems++;
}
public void listAllItems(){
for (int i = 0; i < numberOfItems; i++){
System.out.print(mediaItemTitle[i])
}
}
Here is the second part of code, my second class MediaItem
package p1;
public class MediaItem {
// \/ METHODS
public void MediaItem(){
Library list;
list = new Library();
list.listAllItems();
}
public void MediaItem(String title, String format){
Library call;
call = new Library();
call.addNewItem(title, format);
call.incrementNumberOfItems();
}
// /\ METHODS
}
This is driving me insane. I would love to just have me public variables save their value between methods but its not happening. the console (when 3 is chosen from displayMenu)
0
null
which means numberOfItems and mediaItemTitle[i] are read to be 0, and null. Which I dont understand, because I declared them earlier in the program!!!
I dont understand what Im doing wrong. please help me! Thank you!!
Your main mistake is that you are creating a new instance of Library inside your MediaItem method. That Library object will only live in the scope of MediaItem method. Plus Library is your main static class.
Your design is all wrong in my opinion. It looks like you are learning you way to Java or OOP, which is perfectly fine to have these mistakes.
Separate your data from your main class, create new classes just for your data. Have a look at java POJO (Plain Old Java Objects), like here
For example:
String title;
String format;
String date;
String name;
Should be in a new object, a POJO. Something like:
public class MyDataPOJO {
private String title;
private String format;
private String date;
private String name;
public MyDataPOJO(String title, String format, String date, String name) {
this.title = title;
this.format = format;
this.date = date;
this.name = name;
}
public String getTitle() {return title;}
public String getFormat() {return formate;}
// And the rest of the getter methods for date and name
}
In you Library class you may only need to hold your logic. But even that can be re-factored to another class.
On a side note, please check the java naming convention. Here is a guideline: link. In other words, start you methods name with lower case.
Example, your public void MediaItem(){/** something*/} should be public void mediaItem(){/** something*/ }
Follow the answer above and treat this as a comment, since the persons answer is correct and my statement isn't regarding your primary problem.
In your for-loop, I think you should add another else if statement. If the user enters a number that is not 1-5, they should receive an error. So maybe something like
else if (i < 1 || i > 5)
System.out.println("Error: Enter a choice 1-5\n");
Also, I think you may have forgotten a } to end your listAllItems() method.
But as I was saying, the answer to your real problem has already been handled, so give them the check mark. This is just a minor UI error I noticed.
I'm making a quiz like game. I have two arrays (One with the states and the other with the capitals). Basically it asks the user what capital goes with a random state. I want that if the user inputs the correct state for it to be like nice job or whatever but I do not know how to compare the user input to the specific array compartment. I tried .contains but no avail...
Any help?
My bad - I'm using Java
For Example
if(guess.equals(capitals[random]))
where guess is the string and capitals is the array and random is the random number
Basically you want a mapping String -> String (State -> Capital). This could be done using a Map<String, String> or by creating a State class which will contains its name and its capital as attributes.
But to my mind, the best option is to use an enum as you know that there is 50 states. Here's a small example.
public class Test {
static final State[] states = State.values();
static Random r = new Random();
static Scanner sc = new Scanner(System.in);
public static void main (String[] args){
State random = states[r.nextInt(states.length)];
random.askQuestion();
String answer = sc.nextLine();
if(answer.equals(random.getCapital())){
System.out.println("Congrats");
} else {
System.out.println("Not really");
}
}
}
enum State {
//Some states, add the other ones
ALABAMA("Montgomery"),
ALASKA("Juneau");
private final String capital;
private State(String capital){
this.capital = capital;
}
public String getCapital(){
return this.capital;
}
public void askQuestion(){
System.out.println("What capital goes with "+this.name()+"?");
}
}
Logic similar to this should work. You want to save the user input to a String variable, and then compare it to an n sized array.
for(int i=0; i<arrayName.length();i++)
{
if(userinputString.equalsIgnorCase(arrayName[i])
{
System.out.println("HUrray!");
}//end if
}//end for
Ok so you are somehow producing a random number, and then need to compare the input to the String in the capital Array for that random number/
Im assuming the arrays are ordered such that capitals[10] gives you the capital for states[10].
If so, just save the index to a variable.
int ranNum=RandomNumFunction();
Then just see if
if(capitals[ranNum].equalsIgnoreCase(userInput))
//do something
How do you return an array object in Java? I have an object that has an array in it and I want to work with it in my main class:
// code that does not work
class obj()
{
String[] name;
public obj()
{
name = new string[3];
for (int i = 0; i < 3; i++)
{
name[i] = scan.nextLine();
}
}
public String[] getName()
{
return name;
}
}
public class maincl
{
public static void main (String[] args)
{
obj one = new obj();
system.out.println(one.getName());
}
I am sorry if the answer is simple but I am teaching myself to code and I have no idea how you would do this.
You have to use the toString method.
System.out.println(Arrays.toString(one.getName()));
toString is a built-in function in Java (it might need library import; if you are using Netbeans, it will suggest it).
If the problem is to print it use
System.out.println(Arrays.toString(one.getName()));
//note System, not system
When you do getName() you are returning a reference to an array of strings, not the strings themselves. In order to access the individual strings entered, you can use the array index
String enteredName = name[index] format.
From your program, it looks like you want to print each item entered. For that, you could use a method like the following
public void printName() {
// for each item in the list of time
for(String enteredName : name) {
// print that entry
System.out.println(enteredName);
}
}