So I'm beginning to learn java with the book HeadFirst Java. The books says that all a tester class does is create objects of a new type and then use the dot operator...
I don't really understand what a tester class is and what it does ? and what is the Dot operator and how does it work ?
I'm really new to object/class concepts and already having difficulties with applying them. How to create and return an array of Exam objects? I need to get a data from a textfile which is passed to the method.
Java Code:
public Exam(String firstName, String lastName, int ID, String examType, int score) {
this.firstName = firstName;
this.lastName = lastName;
this.ID = ID;
this.examType = examType;
this.score = score;
[Code] ....
I'm really new to object/class concepts and already having difficulties with applying them. how to create and return an array of Exam objects? I need to get a data from a textfile which is passed to the method.
public Exam(String firstName, String lastName, int ID, String examType, int score)
{
this.firstName = firstName;
this.lastName = lastName;
this.ID = ID;
this.examType = examType;
this.score = score;
[code]....
It looks like an upside down v , i cant find it on my keyboard. I assume its a keyboard combo.
View Replies View RelatedI'm new to Java and I have an assignment to create a Sphere class that will allow you to create Sphere objects using the code below. Then create a program called SphereTester that prompts the user for the radii of two spheres in meters. The program should display which sphere is larger and by how many cubic meters and display only four digits after the decimal point. I have the sphere class given to us for the assignment which is this:
Java Code: public class Sphere {
// instance variable (i.e., a field)
private double radius;
// constructor for the Sphere class
public Sphere(double r) {
radius = r;
[code]....
class Passenger{
String name;
int age;
char gender;
int weight;
public Passenger(){
[Code] ....
This is showing error.....error it gives isthat it cannot change from string type to passenger type......... How to do it??????
I have a String repersentaion of some Object.I want that object convert back into some class type how can I do this?
View Replies View RelatedHow do i go about developing a simple arithmetic tester program which can be used to support young children improve their arithmetic skill. The program should accepts string data for the player's name and the number of questions they want to try, which will be entered by the user. The program should take in the following inputs from the user:
The name of the player, so that the game can refer to them by name in messages. The name must be between 2 and 20 characters inclusive.
The number of sums that the user wants to attempt. This number must be a whole number, and be between 2 and 50 inclusive.
The program must check that the values entered fall within the valid ranges. The program must also check that no empty strings are entered for names.
Once the player has entered their name and the number of questions they want to attempt, the game begins. The program must generate sums for the player.
The program should generate one question at a time and display the question for the user. The questions must involve two numbers and be either a multiplication, division, subtraction, or addition. For example, the following are all valid questions:
3 * 4 = ?
8 / 2 = ?
7 + 1 = ?
9 - 8 = ?
The first number, second number, and arithmetic operator (multiply, divide, add, subtract) should all be chosen randomly, the program should Generate a new random number for each of the three parts of each sum. this requires you to choose one of the four symbols based on which random number is returned.
A few checks must be carried out before a generated question is displayed to the user. If the question is an addition question, no checks are required. If the question is a multiplication question, no checks are required. However, checks are required for subtraction and division sums.
If the question is a subtraction question, the program must check that the second number is equal to or smaller than the first number. Whilst the second number is larger than the first number, new numbers should be generated.
How do you declare methods for a class within the class whilst objects of the class are declared else where?
Say for instance, I have a main class Wall, and another class called Clock, and because they are both GUI based, I want to put a Clock on the Wall, so I have declared an instance object of Clock in the Wall class (Wall extends JFrame, and Clock extends JPanel).
I now want to have methods such as setClock, resetClock in the Clock class, but im having trouble in being able to refer to the Clock object thats been declared in the Wall class.
Is this possible? Or am I trying to do something thats not possible? Or maybe I've missed something really obvious?
I am trying to clear all graphical objects of a certain type(all trees in particular). I have never had any issues doing so, and this method normally works well along with these variables:
Java Code:
public static ArrayList<GRect> historyT;
public static ArrayList<GOval> historyL;
public static GRect trunk;
public static GOval leave;
public void deleteTrees() {
//clears all tree trunks and leaves
[Code]...
That is this normally worked until I started added more trees to the screen after they had all been erased. What happens is that it won't clear all of them unless the max has been reached, that is 6. It will remove all trees up till the last one if the max has not been reached. In other words here is my screen before the clear all if the max has not been reached(* is a tree, _ is erased): ****
Here is it after: _ _ _ _ *
So my question is, is why aren't all the trees deleted? Why does it leave one left behind?
I am simulating a game. This involves creating two Player objects(either HumanPlayer or ComputerPlayer), a TheBoard object, a TheGame object and a TheGameManager object. In the TheGameManager, i am trying to get it so that i can save the two Player objects, the TheBoard object and the TheGame object in current use at some point in the game and then load them later at some point. However, after debugged, i have found that it doesnt like the writeObject() method and skips and sends an exception up.
My TheGameManager class has the following fields:
public class TheGameManager implements GameManager {
private Player player1;
private Player player2;
private TheBoard currentBoard;
private TheGame currentGame;
//private String[] args;
private int iterations = 1;
[Code] .....
I am supposed to write a Tester to get the current volume of a balloon that starts with a radius of 0 after it is inflated.This is the balloon:
public class Balloon
{
private double savedRadius;//instance variable
/**constructor!!
Constructs a balloon with a radius
*/
}
[code]....
I'm having trouble creating two new die objects for the PairofDie class. I'm trying to run two separate die and print the face value and then add both numbers up and print those values as well.
public class Die {
private final int MAX = 6;
private int faceValue;
//private int faceValue2;
public Die(){
faceValue = 1;
[Code] .....
Exception in thread "main" java.lang.Error: Unresolved compilation problems:
The method Die() is undefined for the type PairofDice
The method Die() is undefined for the type PairofDice
at PairofDice.main(PairofDice.java:6)
In the class below I'm trying to create a class that will accept dates in various formats and create a range. The first constructor is easy because I send it the begin date and end date as Date objects. Now I want to send a month(and year) in a constructor and derive the begin and end dates from it. In my constructor that accepts the month/year I need to put the this(startDate, endDate) at the top to be allowed, but the parameters are not built yet.
package com.scg.athrowaway;
import java.util.Calendar;
import java.util.Date;
public class DateRange {
private Date startDate;
private Date endDate;
[code].....
I keep getting this as a result:
Exception in thread "main" java.lang.RuntimeException: Uncompilable source code - Erroneous tree type: myprojects.Balloon
at myprojects.BalloonTester.main(BalloonTester.java:1 8)
Java Result: 1
Is it possible to use a loop to create objects? I'm trying to put together a program (just as a way of learning) to run a horse race.
What I'd like to is have the user enter the number of horses they want in the race, and then create the objects as the user enters the various attributes of the horse (at least the horse's name), and then once all the instance variables have been set, create the first horse object and then move on to the second one, etc, until all the horse objects have been created.
I know I can't use something like a for loop to do it, so how would the code be writte
Our instructor gave us a list of steps to complete after creating a Balloon, but I can't get past just creating it. Search results have brought up other Balloon thread, however I couldn't find a topic about issues just creating the balloon.
package myprojects;
ublic class BalloonTester
{
public static void main(String[] args)
{
Balloon redBalloon = new Balloon("Red Balloon", 100);
[code]....
You have to create a very basic hangman type of game. Open Notepad and create a list of at least ten words in a text file. Save the file as a .txt file and use it to read words for the game. In this game you do not have to show pictures but you do need to keep track of the amount of times that the user has guessed wrong. When the game starts, show the amount of characters in the word represented as dashes and ask the user to type in a letter. if the user guesses correctly show the word again with the correct letter filled in the correct positions(s) and if the user correctly guessed the word, show a message. If the user guesses wrong, keep track of the body parts that needs to be reduced with every wrong guess and inform the user as well, also show a message.
I'm struggling with reading the file, showing the amount of parts left and asking the user to play again. Here is the code:
package hangman;
/**
*
* @author
*/
import java.nio.*;
import java.io.*;
import java.util.*;
public class HangMan {
[code]...
I want to create a program where I need to create an object of list type such as text file will contain nos like 1,2,3,4,5 and write into text file and delete the in FIFO order i.e 1,2,3,4,5...how i can achieve to write a program? I tried bt everytime got concurrent modification exception or Array out of bound exception.
View Replies View RelatedEssentially, the code I want is:
public void randomCreate(ParentObject obj){
int x = random(0-4); //pseudo
int y = random(0-4); //pseudo
create new ParentObj(x,y);
}
ParentObject is actually abstract, so you would only ever pass one of its children objects to it, and a child object of that type would be created. It seems like there should be a way to pass a type, rather than an object, and then create an instance later down, but I don't know if that is actually possible, or if it is poor programming style.
Im looking for a means to store groups of static data..
so I understand these simple string arrays...
Java Code:
private static String[] names = new String[] {
"aidanmack",
"johnsmith"
}
private static String[] ages = new String[] {
"30",
"30"
} mh_sh_highlight_all('java');
But can I not combine that into an array of objects? something along the lines of what you would do with json? like...
Java Code:
private static array[] multi = new array(){
{"name":"AIDANMACK","age":"30"},
{"name":"johnsmith","age":"31"}
} mh_sh_highlight_all('java');
For class, we need to create a word game using classes and objects.
The game is played in rounds. The player is presented with a word that is missing letters. The player has to fill in the missing spaces with their letter guesses. The words presented are chosen with a random number generator which has been provided for us. At the end of the game, the player is shown their score.
In steps, I have to:
-Welcome the player.
-Present the puzzle.
-Allow the player to fill in the blanks.
-Have the program check responses for correct/incorrect input.
-End the game if they have three misses, or continue if they complete the puzzle.
Now, to start, I have a class for the number generator, a class to store the array of 25 words, and a class for the game itself.
Do I need to use inheritance for this type of program? How to move my song list in main to songs and from songs to cd to make 3 separate cd's.
I have 3 classes: main, Cd, and Song. I am having trouble moving the songs from main to the song class and from the song class to Cd.
package p2;
public class Main {
public static void main(String[] args) {
String tempStr;
//array for song names
String [] songNames={
[Code] ....
I want to clarify it whether this below code, when running this loop, will it create separate string objects as strings are immutable or else, will it keep the same reference(as each time inside loop, we use the same name 'rslt') and assign new string value for this?
while(inc < numberOfColumns){
String rslt=rs.getString(inc+1);
rowArr[inc] = rslt;
inc++;
}
How to create object for "class B" and call the "function_B" from other different class D where class D has no connection with class A? Here is my program.
public class A(){
void print(){}
}
class B{
void function_B(){}
}
class C{
void function_C(){}
}
Here, A, B, C are in the same package. But class D is in different package.
How can I do the work below in Java
In this main class, create 5 objects of the class Menu, as defined in the table below.
Name amount of calories cooking time price per person number of drinks
Fufu and Groundnut Soup 564.65 2515.572
Red Red 345 12 9.980
Rice and Beef Stew 560.4 1512.651
Ga Kenkey and Fish 780 10 10.15 1
Banku and Tilapia 450.4 35 25.17 2
Exercise d
In your main class create an array of length 5, and store the 5 objects (Exercise c) into the array. You can use any name for your array.
From the array, use a loop to: Print the details of all the objects using the method you defined in Exercise b.
Exercise e
Use another loop to:
-Print only the name and cooking time of all the dishes that take less than 30 minutes to cook. Hint: you may use the getter methods for the name and cooking time attributes, and then, print these values (name, cooking time).
Exercise f
Use another loop to :
-Calculate and print the total price of all the objects (in the array).
-Calculate the total price of all the objects with VAT included for each dish (VAT rate is 17.5%).
Submission
-Create a folder with your index number as its name.
-Copy your Java Project folder into the created folder.
-Print a hard copy of your classes.
-Submit both soft copy and hard copy of your project