Assigning Private Variables Values From Constructor
Jun 13, 2014
I am able to get output from my constructor when I place a loop inside of it. However when I try to access the private variable that I thought was set by the constructor I get nothing. When I check its size it is zero as well.
Java Code:
public class WinningHand extends PokerCalculator {
private int p1Size;
private int p2Size;
private String[] p1Hand = new String[p1Size];
private String[] p2Hand = new String[p2Size];
import java.util.Scanner; public class Try{ static String name; static int age; static Scanner a = new Scanner(System.in); static Scanner b = new Scanner(System.in); static Scanner c = new Scanner(System.in); public Try(String name, int age){
[Code] ....
I was trying to make a program that asks the user to create a person or a group of persons and assign names and age to them. So I made a constractor "Try" and a method "AskUser".in AskUser() I use a do/while loop where user is asked to input a name, an age and if he likes to create another person. Now how do I take the input data each time the loop runs, and send it to constractor to create new objects with it? And how these new objects will be called?
When creating a class with a constructor, why does one have to create private variables (attributes) to be used as parameters by the object? The object's parameters will be set to be exactly equal to the private variables (attributes), so what is the point of having the private variables (attributes) Why are both private variables (attributes) and parameters needed when they are set to be equal each other anyway?
I thought you can only create a new object using private implementations and then using a constructor to set your arguments inside the parameters of the constructor to the instance variables but how come he created an object without any private implementations and just methods inside the constructor.
import javax.swing.JFrame; public class MyWindow extends JFrame { public static void main(String[]args){ new MyWindow(); } public MyWindow(){ setSize(500,500); setVisible(true); setTitle("MyWindow"); } }
I just recently started learning about encapsulation, how to set variables private and only accessible to other classes through setters() and getters(). I've seen a couple of programming examples, perhaps not enough but some from here, and I sort of built the assumption that by default all variables need to be private. to make things more clear, here's a card dealer I made which simply
1- generates a fulll deck of 52 cards 2- lets user decide how many players, with 5 as Max number allowed as each player is dealt 10 cards. 3- deal cards
I approached this by making A deck , card , player and game class
import java.util.ArrayList; public class Deck { //an Object of this Class would generate a full deck ie an ArrayList of 52 Cards private String[] suits={"Spades","Diamond","Clubs","Hearts"}; private int[] number={1,2,3,4,5,6,7,8,9,10,11,12,13}; ArrayList<Cards> deck= new ArrayList<Cards>();
[code]....
I can understand why for example Deck class's suit and number arrays are set to private , as they only need to be accessed by this class only. however, both the Deck class's deck arraylist and the Player class arraylist are not private, as I need to transfer these values from one to the other and it felt to me that setting them to private would make it more difficult to deal with them, but what I did instead is to set the Game class dealCard(), which is the only method that have access to them as private. does this achieve the same effect or do I need to set both of these arrayList to private?a follow up question, this is more related to the actual card dealer program, in this code
private void dealCards(){
for(int x = 0 ; x < playerCount ; x++){ for(int y = 0 ; y < 10; y++){ playerList.get(x).pile.add(deck.deck.get(0)); deck.deck.remove(0); } } }
is there an API in ArrayList class that moves(adds to receiver and remove from giver) element across ArrayLists?
so, i was reading my java book and learning about objects and methods and it starts talking about Encapsulation and mentions that it's good practice to set instance variables as private and instead of accessing the instance variables directly, we should create a set method and get method to get and set the stuff we want to pass to the class containing the object...
for example, in this class, we're passing the integer 70 for object dog one and integer 8 for object dog two for the dog class... and these these 2 integers are sent to the setsize method so we're not accessing instance variable size directly.
i dont quite get it though....if we the programmer are the one deciding what size the integer is for the dog, and the setsize method takes the one.setSize(70) or (8) and puts them in setsize(int s) as s... but only to copy that integer stored in s back to private int size.... why do we even need to bother with making these two extra methods such as setSize, getSize?
in the book it says that... well what if the code gets into the wrong hand and someone writes something like one.setSize(0) then you would get a dog with size 0 which is essentially illogical. but then again, i'm the programmer, and i am the person who writes the code and passing the right integer.The reason for public and private... that part i understand... i can see why if a variable's data can get changed amidst the code during calculations and you dont want it to directly change the original variable and have it mess up the code, but this code from the book just a bad example of demonstrating the reason? since we manually pass the information ourselves and passing it to method setSize... and all setSize does is stores it in another integer, only to copy it right away to size (which is the original private variable we were tryign to protect?
Any simple code to demonstrate how the code might end up changing an instance variable and why we would want to protect it by using private?
class GoodDog { private int size; public int getSize() { return size; } public void setSize(int s) { size = s;
I have an requirement of splitting a Date-Time String i.e. 2013/07/26 07:05:36 As you observe the above string has Date and Time with space in between them.
Now I want just want split the string not by delimiter but by length i.e. after 10th place and then assign it to 2 variable i.e. Date <----2013/07/26 and Time <---07:05:36 separately.
I am writing a program that accepts input from the user, I want default values displayed before the input values.
Java Code:
public surfboards() { surfboardType = "Type not assigned"; shaperName = "Shaper not assigned"; constructionType = "Construction Type not assigned"; surboardSize = 0D; } mh_sh_highlight_all('java');
I can get the output to display as shown below
(THIS IS WHERE I WANT DEFAULT CONSTRUCTOR DISPLAYED. Currently not displayed)
Type not assigned Shaper not assigned Construction Type not assigned 0 Feet
(THIS IS WHERE I WANT DEFAULT CONSTRUCTOR DISPLAYED. Currently not displayed)
input:
Java Code: Enter Surboard Type: test Enter Shaper Name: test Enter Surfboard Construction Medium: test Enter Surfboard Size: 6.5 mh_sh_highlight_all('java');
So I want to write a constructor that creates a new object with the data from the array values. I don't know where to start. It's the last method in the code:
public class Measurements { private double[] values; private double[] newArray; private int n; //numberofvalues private double[] ms; public Measurements(int max) { //constructor
while (key != 3) { if (key == 2) { System.out.println("Input from a file"); // System.out.print("Enter file name: "); // String str = expression.nextLine(); int i = 0; File file = new File(
[code]....
What I need to happen is the file gets read in, the file is in the form:
a * ( b + c ) / 2 + ( 8 * b ) a = 5 b = 10 c = 20 ( x + y ) * z x = 13 y = 21 z = 3
And so on. My code is supposed to start at the beginning and have output like:
Infix: a * b ( b + c ) / 2 + ( 8 * b ) variable values: a = 5 b = 10 c = 20
**It then needs to store the variable names along with their values in a hash table**
postfix: a b c + * 2 / 8 b * + value: 155
And it continues reading the file in the same fashion.
My issue is I am not properly extracting the variables and their values from the file. I have the variables in an array list actually, so I have those, but don't know how to efficiently navigate to the values, then store the character and value in a hash table, while protecting against possible blank lines within the file. Thus just calling nextLine()s and next()s wouldn't work to get to values because they would lead to an error.
I am facing difficulties in identifying the proper way to add the selected colors of cards into an arraylist. I am having an arraylist which is:
Java Code: private List<String> selectedCars = new ArrayList<String>(); mh_sh_highlight_all('java'); And one more for the carColors:
Java Code: private List<String> carColors = new ArrayList<String>(); mh_sh_highlight_all('java');
The selectedCards array will store the selected cars ['TOYOTA','MAZDA','NISSAN'] as per the selection from the user.For certain types, there is one default color which is 'Black', however for some of them, the user can select different colors.(ex. if selection is 'Toyota') Java Code:
String carColor=""; String toyotaColor=""; // The value will be retrieved from the form once the user selected the color if (selectedCars.contains("MAZDA")) { carColor="Black"; } else if (selectedCars.contains("TOYOTA")) { carColor=toyotaColor;
while (gamesPlayed<gameQty) { userChoice = JOptionPane.showInputDialog("Rock, Paper, or Scissors?"); //Determine winner for each game if (compChoice.equalsIgnoreCase(userChoice));
[Code] ....
It seems to circle through the loop gameQty times, without comparing.
In my JSP I need to retrieve some data from MySQL. I need to assign a "email" variable to the "WHERE" clause. The variable is retrieved from the session attribute. So far, I have this code:
<sql:query dataSource="${user}" var="result"> SELECT * from users where email = ${sessionScope.email}; </sql:query>
I have a program that using one JFrame which opens one of two JDialog windows depending on which button is pressed.
How do I assign listeners to the buttons and fields on the JDialog window? I added listeners on the View end, but how do I process them? I tried adding the '..implements ActionListener" class in the main Controller but it does not recognize/hear anything.
I have been asked to write a library program that will keep record of books and the year it was published. The program should ask the user how many rows he wants accept the string input from the user and display them in rows and columns. This is how i code it
package multidimension; import java.util.Scanner; public class bookrecords { public static void main(String[]args){ //declaring a scanner variable Scanner input =new Scanner(System.in);
I have a txtfile which I read and go through. My question is what are the ways I could do to read a txtfile of words and assign an empty score to each of the word in it. So each word will have a 0 value. Later on I will manipulate the score but for now I want each word to have a 0 score.What I have at the moment is reading a text file full of words eg:
private void readtextfile() { try { Scanner rd = new Scanner( new File("filename")); List<String> lines = new ArrayList<String>(); while (sc.hasNextLine()) { lines.add(sc.nextLine());
[code]...
how to make each of the words to have a score of zero 0?
byte b = 100; it works (implicit conversion of implicit int literal 100 to byte.
But if you have a methodvoid bla(byte b){}
And want to invoke it with a literal (which is an int by default):bla(8) then there is no implicit conversion.
Is the byte b = 100; just an exception in Java? And is it the rule that one has to explicitely cast (narrow) integer literals when passing to smaller-than-int types?
I am looping through data in Android, using Parse data. I came up with this as a way to get user information; the larger goal is to create a model of data that I can use in an array adapter, so I can create a custom list view (as described here [URL] .... In the example, the data are hard-coded, not pulled from a database.
public static ArrayList<Midwifefirm> getUsers() { //Parse data to get users ParseQuery<ParseUser> query = ParseUser.getQuery(); query.orderByAscending(ParseConstants.KEY_PRACTICE_NAME); query.findInBackground(new FindCallback<ParseUser>() {
[Code] ....
The intention is that for every user that does not have the type patient, collect this data about them, then store it in the arrayList.
On the return statement, though, there is an error: cannot return a value from a method with a void return type.
I may be over complicating this...read through various sources to get a model for this...in the end, I want to display a list of information about specific users, after the user makes a selection of a city...it would therefore display all the information about the medical practices in that city.
So I'd like to know what all the statement, not sure if it's the correct way of calling them but I'd like to know what like all of those purple-ish colored words in eclipse actually mean.Here's what I know so far, so if you can add some stuff to it or just correct me:
public - can be accessed by different classes. private - can't be accessed by different classes. static - adds a '.' which pretty much lets you like use methods on it? Not really sure about this one. final - a final value of a variable meaning it couldn't and willn't change? super - I have no clue, maybe something that has to be executed first? Not sure. void - bassicly you don't have to use return as it doesn't return any value. this - Uh-.. I think it has something to do with the class this keyword has been entered into, not quite sure what it does though.
I assume there are alot more but I am just not sure about these common ones, what the actually do and what's their purpose?
I am creating a slot machine using eclipse. I am trying to get the "winnings" JTextField to be updated in a way so that when the random images have been selected it adds to the number that is already displayed in the JTextField as opposed to what it is doing at the minute which is just displaying how much was won on that particular spin. I am also struggling to set a code for when noting is won, nothing is added. My code is below.
