I have to write programs using inheritance and got everything working but need to set a value for side1 in the cube class.
public class Cube extends ThreeDimensional{
public Cube(){
super();
} public double setOneSideofCube(){
//side1 = setOneSideofCube();
return side1;
[code]....
I am having trouble with a mouse click method. In short I have a hexagon grid, and every time I want to click on one particular hexagon I want the color of the hexagon to change to blue(by default the color is grey). This part works, but when I go to click on another hexagon I want the color of the previous hexagon to change back to grey while at the same time changing the color of the current hexagon clicked to blue. So in other words, I only want one hexagon blue at a time. How might I do this?
I have a hexagon class for one particular hexagon, and a hexmap class for multiple hexagons. I know I should probably be handling mouse clicks in the hexmap since it deals with the whole thing. But I cannot say something like hexagon.setColor within a mouselistener in that class(it gives me a lot of issues). Here is some of my code :
public class Hexagons()
public Hexagons(HexMap theMap, int mapRow, int mapCol, int width, int height) {
this.map = theMap;
this.row = mapRow;
this.col = mapCol;
this.width = width;
this.height = height;
[Code] ....
The error I get when I execute my java file.
Exception in thread "main" java.lang.NullPointerExceptionat DogTestDrive.main(DogTestDrive.java:19)
Here is the source
class Dog {
int size;
String name;
void bark () {
if (size < 60) {
System.out.println("Woof woof");
[code]....
Some background: I'm reading "Head first Java 2nd edition" and I'm going through the examples which is showing me how to change the state of an object. The original code looks like the code below, however the previous chapter went over creating array's of an object, so I created an array of the object "Dog" and wanted to re-write it this way. To my understanding, it should work but it's giving me that error when I execute it. The error itself isn't very clear, if I could get a line number pointed to, that would work.
class Dog {
int size;
String name;
void bark() {
if (size > 60) {
System.out.println(“Wooof! Wooof!”);
} else if (size > 14) {
System.out.println(“Ruff! Ruff!”);
} else {
System.out.println(“Yip! Yip!”);
[code]....
I am trying to print out a rubix cube nicely so that it looks something along the lines of this:
** ** ** R1 R2 R3 ** ** **
** ** ** R4 R5 R6 ** ** **
** ** ** R7 R8 R9 ** ** **
B1 B2 B3 Y1 Y2 Y3 G1 G2 G3
B4 B5 B6 Y4 Y5 Y6 G4 G5 G6
B7 B8 B9 Y7 Y8 Y9 G7 G8 G9
** ** ** O1 O2 O3 ** ** **
** ** ** O4 O5 O6 ** ** **
** ** ** O7 O8 O9 ** ** **
** ** ** W1 W2 W3 ** ** **
** ** ** W4 W5 W6 ** ** **
** ** ** W7 W8 W9 ** ** **
however, when I try to print out the entire cube, I get this:
** ** **
** ** **
** ** **
R1 R2 R3
R4 R5 R6
R7 R8 R9
[code]....
I have found out the area that causes this, my toString, but I want to know if there is something built in or not that will allow me to print it such that I can continue printing it at the same row level as its neighbor, even though I create a new line for each individual column? Here is the code that I try to print out the entire cube:
void printEntireCube(){
for(int row = 0; row < 4; row++){
for(int col = 0; col < 3; col++){
System.out.print(cube[col][row] + " ");
}
System.out.println();
}
}
void createCube(){
[code]....
import java.awt.*;
public class Exercise5 {
public void paint(Graphics g) {
g.drawRect(30, 50, 50, 50);
g.drawLine(30,50,40,40);
g.drawLine(80,50,90,40);
g.drawLine(40,40,90,40);
g.drawLine(80,100,90,90);
g.drawLine(90,40,90,90);
}
public static void main(String args[]) {
}
}
I got how to create the cube, but how do i loop the drawline? I am supposed to only have one ?
My question is, how do I get my Cube to visualize in the JPanel? I've tried a bunch of add methods but they don't compile. Is there a proper method I can use to add an object to a JPanel?
import javax.swing.*;
import java.awt.Dimension;
import javax.swing.Timer;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.*;
[Code] ....
I need to work on this "Dice" program. I've done it twice already. I've also been pouring over examples on here and elsewhere online, but none of them exactly match what I'm doing, as they all say "Pair of Dice".Mine says: "Create a class called Dice to represent a SINGLE cube". It should have a method called roll() that randomly selects a number from 1-6 for the value of the dice."
It has to use java.util.random, not math.java, and it has to have numberShowing:int, roll():int, and main() all in it.The last part reads "Create a test main method for the Dice class that creates a dice and rolls it many times. Can you keep track of how many times a number comes up? Describe how or implement it in the program." I have started at this computer for hours, and read as much info as I can.
Write a Java program that calculates the area and volume of a cube, sphere, cylinder, and regular tetrahedron. Your program should obtain the necessary input for each of the objects from the console and output the input, area, and volume of the object. Use appropriate messages to guide the user of your program.
Here what i did, i am not sure if this is what the assignment want, but this is the best method i could come up with
//Khang Le
import java.util.Scanner;
public class InputAreaVolume {
public static void main(String[] args) {
[Code]......
Write a Java program that calculates the area and volume of a cube, sphere, cylinder, and regular tetrahedron. Your program should obtain the necessary input for each of the objects from the console and output the input, area, and volume of the object. Use appropriate messages to guide the user of your program.
View Replies View RelatedCreate an equals method that takes an object reference and returns true if the given object equals this object.
Hint: You'll need 'instanceof' and cast to a (Geocache)
So far I have:
public boolean equals(Object O){
if(O instanceof Geocache){
Geocache j=(Geocache) O;
if (this.equals(j)) //I know this is wrong... but I can't figure it out
return true;
}
else return false;
}
I think I have it correct up to the casting but I don't understand what I'm suppose to do with the this.equals(). Also I'm getting an error that I'm not returning a boolean... I get this all the time in other problems. I don't get why since I have to instances of returning booleans in this. "returns true if the given object equals this object" makes no sense to me. I assume the given object, in my case, is 'O'. What is 'this' object referring to?
I am trying to align the core/middle side color of a cube, index 4, with the bottom middle color of the same side, index 7. (Each side has values 0-8 where 0 - is the top left corner, 1 is the top mid corner, 2 is the top right corner, 3 is the middle left corner, etc).
In addition to lining up those two colors, I am also making sure that the neighbor color of index 7(the color that it is attached), in this case the bottom color, matches with the top core/middle color. I will attach some pictures and a print out to show what I am talking about...
However, in my code when I am trying to align all of these up together, it does not go into the while loop. Each of the loops essentially is trying to get a match of same color with index 4 and 7, as well as making sure that index 7's neighbor color (the bottom color, in this case) matches with the top color.
Here is what I have tried:
private void alignSideColor(){//make the bottom colors neighbor match with a middle side value and rotate it to the top, for the top cross
if(cube.bottom.square[1].charAt(0) == topColor){
while(cube.front.square[7].charAt(0) != frontColor && cube.bottom.square[1].charAt(0) != topColor){
rotateBottomClockwise(1);
System.out.println("Trying to align side color...");
[Code] .....
The print out of the ELSE IF is:
alignment is: W-G and tops: R-R
NOW ITS ALIGNED
even though the sides, index 4 and 7, are NOT aligned with each other
I have also tried the same thing but with out the 2nd condition in each while loop, and although is DOES enter the while loop, it does not perform correctly -- index 4 and 7 WILL have matches colors, but it does not check to see if index 7's neighbor matches with the top color.
Here is how it prints out
** ** ** G7 B6 Y1 ** ** **//this portion is the back of the cube
** ** ** R6 W5 O4 ** ** **
** ** ** R3 W2 O1 ** ** **
B3 G4 Y9 W9 O8 Y7 W3 B4 G9//this portion is the left, top, and right of the cube
B2 G5 R8 W4 R5 Y6 O2 B5 G8
O7 W8 R9 B7 B8 B9 R1 R4 R7
** ** ** O3 O6 O9 ** ** **//this portion is the front of the cube
** ** ** Y2 Y5 Y8 ** ** **
** ** ** B1 G6 W7 ** ** **
** ** ** Y3 Y4 G1 ** ** **//this portion is the bottom the cube
** ** ** R2 O5 G2 ** ** **
** ** ** W1 W6 G3 ** ** **
Here is the cube showing the top, left and front side
Here is the left and bottom side. As you can see index 4, G5 -- yes that is a 5 lol -- does not have the same color as index 7, W8.
I need to rotate the bottom until W8 is aligned with a middle white value. An examples of a neighbor is: W8-R2
I am new to Java and have read books, the Java docs, and searched the Internet for my problem to no avail. I have an Array of objects that contains strings. How can I get the object's strings to print in a list so that the user can select that object to manipulate its attributes? For example, the user can select "Guitar 1" from a list and manipulate its attributes like tuning it, playing it, etc. I have a class called Instruments and created 10 guitar objects.Here is the code:
Instrument [] guitar = new Instrument[10];
for (int i = 0; i < 10; i++) {
guitar[0] = new Instrument("Guitar 1");
guitar[1] = new Instrument("Guitar 2");
guitar[2] = new Instrument("Guitar 3");
guitar[3] = new Instrument("Guitar 4");
guitar[4] = new Instrument("Guitar 5");
guitar[5] = new Instrument("Guitar 6");
[code]...
can a keyevent in java make the space ship and the laser too ?
View Replies View RelatedFor example I create an object like this:
BankAccount b = new SavingsAccount();
Now lets say that I want to access a method 'addInterest()' that is in the 'SavingsAccount' class I would have to do: '((SavingsAccount)s).addInterest();'
The question I have is why do I have to cast 'b' to SavingsAccount? Isn't the actual object reference of 'b' already an instance of 'SavingsAccount' class? How does the 'BankAccount' affect the object itself? I'm really confused as to what class is truly getting instantiated and how BankAccount and SavingsAccount are both functioning to make the object 'b'.
I don't understand why the object reference variable 'a' cannot be recast from a thisA object reference to a thisB object reference.Is it the case that once a reference variable is linked to a particular object type then it cannot switch object types later on.I am facing the Java Associate Developer exam soon and I am just clearing up some issues in my head around object reference variable assignment,
class thisA {}
class thisB extends thisA { String testString = "test";}
public class CastQuestion2 {
public static void main(String[] args) {
thisA a = new thisA();
thisB b = new thisB();
[code]....
I am trying to get this to where I can type in a name and it will search through each object and print back the corresponding object info.
Java Code:
import java.util.Scanner;
public class MyPeople {
public static void main(String[] args) {
Person[] p = new Person[] {
new Person("Chris", 26, "Male", "NJ", "Single"),
new Person("JoAnna", 23, "Female", "NJ", "Single"),
new Person("Dana", 24, "Female", "NJ", "Single"),
new Person("Dan", 25, "Male", "NJ", "Single"),
new Person("Mike", 31, "Male", "NJ", "Married") };
[code]....
Task:The main method of the class Things below creates an object called printer deriving from the class PrintingClass and uses that object to print text. Your task is to write the PrintingClass class.
Program to complete:
import java.util.Scanner;
public class Things {
public static void main(String args[]) {
String characterString;
Scanner reader = new Scanner(System.in);
PrintingClass printer = new PrintingClass();
System.out.print("Type in the character string for printing: ");
characterString = reader.nextLine();
printer.Print(characterString);
}
}
// Write the missing class here
Note: In this exercise the solution is part of a conversion unit where many classes have been declared. Because of this the classes are not declared as public using the public attribute.
Example output
Type in the character string for printing: John Doe
John Doe
My Class:
class PrintingClass {
public void print(){
System.out.println(characterString);
}
}
If I set a Jlist to contain an array of objects, how can I display properties of each object instead of the object array list itself. Ex:
Instead of:
Person1
Person2
Person3
display values such as each person name within the Jlist:
Mike
Paul
Andrew
I have just started working with linked lists. I have a linked list of Objects and I want to be able to search for a specific object. But currently my code continues to return false. Also how would I go about removing the first index of the linked list.
public static void main(String[] args) {
LinkedList<Cookies> ml = new LinkedList<>();
int choice = 0;
while (choice >= 0) {
choice = menu();
[Code] ....
I am reading Head First: Java and got to Object References. In the book I got a little bit confused on what happens when two object reference's point at the same object so I wrote a small crude test, the below code. This of course clarified what happens but what I am interested in knowing is in what circumstances would you want to have two separate references for the same object when you could just use the original? Eg. v1
class ObjectValue{
int objVal = 1;
}
class ObjectValueTestDrive{
public static void main(String [] args){
// "Value of v# should be" refers to if it copied the given object values, instead of referencing the same object
ObjectValue v1 = new ObjectValue();
System.out.println("Value of v1 should be 1:" + " "+ v1.objVal);
[code]....
Explain anonymous objects with example clearly...i read some where anonymous objects advantage is saving memory...it is benificiable when there is only one time object usage in our program..i can't understand one time usage of object ....i know anonymous objects but i don't know in which context we use them in our programs...i did the anonymous object program with my own example but i can't differentiate this one with normal object..i'm providing my own example below
//anonymous object
public class anonymous {
int x=10;
int y=25;
void display()
{
System.out.println("anomymous");
[code]....
What I want to do is have a label that is updated whenever an object gets some new, relevant data.The way you do it in Java looks different from the way we do it in Objective-C. In Objective-C, we have what's known as a protocol. An Objective-C protocol is almost exactly like a Java "implementation." In Obj-C, if I want the user to see the address of where he is, I can have an object that gets the information and invokes a view controller's method; at that point, the view controller would then take the data passed to it and display the data in a label. However, the view controller is an instance of a subclass of the bundled view controller class.
View Replies View RelatedI am trying to find either some references to point me on the right track with passing an object with all of it's properties still in tact after it's been created. Currently I am trying to do this through an interface but it seems to just create a new object everytime without the properties. Example below :
import java.util.ArrayList;
import java.util.List;
public interface TPerson{
//public Person p = null;
}
class Thrower {
Person p;
[code]....
When I implement the interface on the other objects as soon as I call the setP method shown above it seems to just create a new one even though I pass the object to the method I want to use.
difference between object reference and object
View Replies View RelatedI've been trying to learn Java for the last 36 hours or so (after applying for a HTML/CSS job saying "Java knowledge preferred"), and decided to experiment a bit making a graphical tic-tac-toe game. I eventually managed to get that done and it's working. Working code below:
[Java] tic tac toe 1 - Pastebin
So, it works to an extent, however, the way I am capturing which cell is selected seems very sloppy, and would not work if the cells weren't squares or rectangles. So I made a copy of the project and restructured it adding the mouse event to the cells, but now I can't get JComponent to repaint. New code below:
tic tac toe 2 - Pastebin
Curiously, clicking triggers the action for all 9 cells, but I presume it's because I haven't bounded them making it think I've clicked all 9 simultaneously.
What I've tried:
Make the Cell class extend the game class and call this.repaint()- causes stack overflow.
Calling Game.GameState() within the cell clicking event and making that function static - compiler doesn't like calling repaint() inside a static function.
Making another class to make a clone of the Game object and then refresh- was never going to work....
I have a value object class and it has the below member
XMLDocument request = null;
Should I instantiate it in the VO class as
XMLDocument request = new XMLDocument();
or leave it null and let the calling program instantiate it?
What's the proper way to do it for Value Object classes in java ?