When I run this (entering 12 for both questions) I get this error:
java.lang.ArrayIndexOutOfBoundsException: 12
at MathTablesTwo.main(MathTablesTwo.java:22)
Also, what would be the proper way to organize my code into blocks?
import java.util.Scanner;
public class MathTablesTwo {
public static void main(String args[]) {
Scanner input = new Scanner(System.in);
[code]....
Lately I've been working with JDBC and writing queries in some Java programs. I've noticed that I keep experimenting with where I place my blocks of querying code. I've tried creating a private method in the class where the query is used, I've created utility classes where I can call the query when needed, and sometimes I've just put it in a localized block of code where I need to. Also, most often these queries are one-shot queries where I need to pull the data to populate a JTable.
In short, this has made me realize that I don't have a solid practice for organizing my queries in Java. So my question is "Is there a practice for organizing query code?".
I've already seen large code blocks inside JSP's, in a way it is very hard to maintain the web application. Is there a way to avoid that?
View Replies View RelatedI have a program where I have to open a file and then run a piece of code to do something with it. However since there are different files I want to run different pieces of code depending on the file. I have a JFileChooser setup and it works but I would like to have a something like an if else depending on the file extension.
View Replies View RelatedIf I wanted to take strings in from the user through a GUI say day, month, year. I am looking for a way to organize those incoming strings. I am going to add this information to a queue. However, I want the people who put in the earliest day, month, and year to be put into the queue first followed by the next earliest so on and so forth.I was thinking what I would need to make a method that would compare the information.
View Replies View RelatedI am trying to write a program that read from a csv file called matches.csv.
A single football match can end with a win or a draw: in first case the winner team get 3 points and the loser none, in the second case of draw each of the two teams get 1 point.
For example, the first line of the file matches.txt is as follow:
In the file it contains the following data.
17/08/2013ArsenalAston Villa13
24/08/2013Aston VillaLiverpool01
This means that a match has been played on the 17/08/2013 where Arsenal scored 1 goal while Aston Villa 3 goals: thus Arsenal got 0 points while Aston Villa 3 points.
How can I structure my output to make it make it read
Position Team Played Points
1 Aston Villa 2 3
2 Liverpool 1 3
3 Arsenal 1 0
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class Teams {
public static void main(String[] args) {
String fileName = "matches.csv";
File file = new File(fileName);
[code]....
I have a couple of objects, which I will call height and width. The latter may depend on the former and I access them through an interface:
interface Height
{
double getHeight();
}
interface Width
{
double getWidth( Height height );
}
I then have something I will call a RectangleMaker, which represents some set of rectangles that can be made. It takes a list of heights and widths and keeps track of which ones have been selected and which ones can still be made. For example, the possible heights might be 2 or 3 and the possible widths 3 or 4. It needs to determine if it can make a rectangle with a specific area and if selected to make that rectangle, disallow any other heights. So if I said, you are in charge of 2 x 3 rectangles, it could still potentially also make 2 x 4 rectangles, but 3 x 3 rectangles would no longer be an option. For the most part I think these details are irrelevant to my question, which is really about organization and assignment of responsibilities.
interface RectangleMaker
{
void setHeights( ArrayList<Height> );
void setWidths( ArrayList<Width> );
boolean isAreaAvailable( double Area );
void selectDimension( Height height, Width width );
Height listAllowedHeight();
ArrayList<Width> listAllowedWidths();
}
Now I have a new requirement. The lists of heights now need to be associated with a source, as do the widths. I should keep track of a list of RectangleMakers and pick the 'most appropriate' one for a particular area. The rule is to sort first on the height source and then on the width source and the first one able to handle the area, gets the job. So I created two enums heightSource and widthSource and had RectangleMaker implement Comparable, so I can make an ArrayList<RectangleMaker> and sort it based on the rules. Then I traverse the list and the first one that returns isAreaAvailable() true gets the job.
The final bit is that these sources also imply a specific set of Heights or Widths. How I get that set varies, it may be a fixed value or values, or might be read from a file. So in principle I could have:
ArrayList<Height> buildHeights( RectangleMaker.SOURCE source )
{
switch ( source )
{
}
}
and have a lot of specific code that builds each list by whatever method is appropriate. I still need to deal with the fact I might need additional information to build the lists. For example, one source might require a min, max and increment and another might require a file name. So I started working in the direction of more interfaces.
interface HeightList
{
ArrayList<Height> getHeights();
RectangleMaker.Source getSource();
}
I am not totally comfortable with my enum lists. They solve the sorting problem, but I am not exactly sure which class should define them. Right now they are defined by the RectangleMaker. I would need to update this class every time I added an implementation of HeightList or WidthList.
I was also thinking that since the list is built from a specific source, that source should be associated with the list. That would lead me to make this change:
interface RectangleMaker
{
void setHeights( HeightList heightList );
void setWidths( WidthList widthList );
boolean isAreaAvailable( double Area );
void selectDimension( Height height, Width width );
Height listAllowedHeight();
ArrayList<Width> listAllowedWidths();
}
It seems maybe there should be a factory in here somewhere, but this is where I am having trouble sorting out exactly who has what responsibility. I can do this sort of thing with my HeightList interface:
class SpacedHeight implements HeightList
{
int start;
int end;
int step;
ArrayList<Height> heights;
RectangleMaker.SOURCE source;
[Code] ....
Should I be thinking of putting one more layer over all of this? What complicates my thinking are two things: multiple instances may have the same source and some of these instances are dynamic. For example, two SpacedHeight instances may have different ranges, but they are both SpacedHeight and it doesn't matter which gets picked first. Exactly what SpacedHeight instances get created is determined by prompting the user for the values. If the heights come from a file, every instance would be associated with a different source and the file names would be hard-coded.
I think I want to make a HeightFactory and I think then it would make sense to move my enum definitions there. I see how I would do that if I could hard-code a specific instance of a HeightList with a specific enum. I am less clear on how to handle the case where the factory needs different parameters for different HeightList implementations.
I'm trying to program a tile-based map editor and most of it is going quite smoothly except trying to organize the layout. Originally I was going to use 2 frames, one for the map, and 1 for the tile set, but after reading about frames I learned that that is bad practice and is also inconvenient because there is no way to have both frames in focus at once (so you need to click an extra time to gain focus when switching windows). So what I'd like to do is create a single frame application that holds 3 panels. One for the map, one for the tile set, and one for tile settings. This is basically what it would look like:
Note that the tile settings panel uses GUI elements (a border, a JLabel (which starts out empty), a JComboBox, and a JTextField) while the other 2 panels are just drawing panels*
Now I have tried multiple things which either did not work visually (panels were inside panels) or did not compile. One thing I tried was using BoxLayout to put the 2 tile panels vertically within a temporary panel which I then tried to add into the frame after the map panel (with FlowLayout), but that made it look like this: I honestly don't know what else I did that I should write here because in retrospect many of the tings I tried were silly or I don't remember exactly what I did. What would be the best layout to doing what I want?
I'm currently taking a computer program design class which has done a lot for my understanding of how to organize classes, but isn't giving me challenging enough assignments and I don't believe it's going to be covering interfaces and abstract classes, which is a shame. So I've been digging into these topics myself and decided to work on my own program (an Uno game program) that would utilize everything we've been learning and give me some practice with GUIs.
My current plan:
Have an abstract UnoCard class that determines the basic properties/methods common to all cards. Create a class for each card type extending from UnoCard, which would be - the generic card (number and color), action cards (skip, reverse, draw two), and special cards (wild, wild draw four, and blank).
Two enums, one for color, one for rank (which includes the numbers, as well as the action and special card ranks (reverse, wild, exc.) ).
A deck class would have an ArrayList <UnoCard> property and it's constructor would initialize a fresh deck.
A hand class that also has an ArrayList <UnoCards> where it gets said cards from the deck class.
A discard pile class, which contains the cards discarded and the current card in play.
A "board" class (haven't figured out a better name for it yet) which would determine/keep track of the number of players/hands, the turn order, the locations of the cards, and the winning condition.
Area of confusion and concern I'm having:
From what I've read, I want to avoid circular dependency. So if that's the case, when a card type effects the state of a "hand" or the turn order or really anything else, then in what class do I place the method(s) that effect that? If I place it in the specific card class, wouldn't that create a circular dependency? So would it be better then to have the hand class figure out what can be done with a specific card and what that specific card effects (which wouldn't that hinder the cohesion of the class?)?
I was also thinking a possible solution might be to have the non-generic card types contain methods that return values as apposed to manipulating higher level classes, such as a boolean drawCards which returns true if cards need to be drawn, false otherwise (same for skip, reverse, exc.).Then maybe the board class can determine what to do if those values are true or false (which actually seems more convoluted since only one value would be allowed to be true at any given time).
The other solution I was considering is to have a single UnoCardRules class, which serves the sole function of providing methods to determine the effects of each card, that way each card class can only worry about defining the card's state.
why am I not getting a proper shape of "Leftarrow"? The result should look like the following (the system draws the arrow abnormally, so the beginning should a real ARROW:
*
* *
* *
* * * * * * * * *
* *
* *
*
here is the class:
Java Code: public class LeftArrow extends ShapeBase {
private int lengthOfTail;
private int widthOfArrowHead;
[Code]....
import java.io.*;
import java.util.List;
import java.util.ArrayList;
public class ListOfNumbers {
try
[code]....
i tried this code in BlueJ IDE.it told me i had an illegal beginning for "try".am i not supposed to use try for main methods?
So I need to print out the table of conversions from kilogram to pound and from pounds to kilograms. I think I have done a while loop correctly, but it is hard to actually check it since I do not have proper output format. I have tried also %4.2f format option however could not find the proper position in the print.
public static void main (String[] args){
System.out.printf("%10s%10s | %10s%10s
", "Kilograms", "Pounds",
"Kilograms", "Pounds");
System.out.println("---------------------------------------------");
[code]....
I have a signed certificate from Entrust which I used to sign a DeploymentRuleSet.xml file. I placed the DeploymentRuleSet.jar in the proper location C:WindowsSunJavaDeployment, afterward the java control panel's security tab shows a link to "show the active deployment rule set" which did not exist prior to coping the file to the directory. When I click on the link a new window opens and says "Rule Set not found" ....
View Replies View RelatedI am trying to make a pyramid from blocks . I know that for example to make a bigger block from small blocks you write something like :
for(int i = 10 ;i <=1 ; i--){
for (int j= 10 ;j <= 1 ; j--) {
< statement to create block where you use both i and j to define the location of each block>
}
}
but i cant seem go grasp how to make a pyramid , so far my best effort is :
int i =10 ;
while (i >=1 ) {
for( ; i>=1 ; i-- ){
< statement to create block > }
}
At the moment visually i don't get a pyramid but it might be because of other issues and not because of the while and then a for inside it approach .
My approach is correct and if now what would be the correct one to create a pyramid from smaller blocks ?
What static initialization blocks do in java?
View Replies View RelatedI'm reading the following section of the Oracle docs:
Guarded Blocks (The Java Tutorials > Essential Classes > Concurrency)
We have multiple threads. One of them sets the joy flag to true. The other waits until joy flag is set to true in order to print to the output stream. Rather than squander processer resources with a while loop, we choose to use the wait method of Object which suspends execution of thread. When the other thread throws an exception, we check the loop condition again.
Java Code:
public synchronized void guardedJoy() {
// This guard only loops once for each special event, which may not
// be the event we're waiting for.
while(!joy) {
try {
wait();
} catch (InterruptedException e) {}
}
System.out.println("Joy and efficiency have been achieved!");
} mh_sh_highlight_all('java');
The documentation goes on to state the following:
When a thread invokes d.wait, it must own the intrinsic lock for d - otherwise an error is thrown. Invoking wait inside a synchronized method is a simple way to acquire the intrinsic lock. When wait is invoked, the thread releases the lock and suspends execution.
The statement seems somewhat contradictory. When we invoke wait inside a synchronized method, is the intrinsic lock acquired or released? I thought it was the synchronized keyword itself that acquired the intrinsic lock.
Below is a method that is suppose to insert a value inside a stack based on the index. I thought it would be easier to copy the value, if any, that was in the index into the variable holder and replace it with the input value. After in which it would copy the holder value and place it at the top of the stack. (topOfStack variable is what the holder is copying too.)
public void pushExact (int index, String input) {
String holder = "";
if (maxSize == 0) {
theStack[topOfStack] = input;
topOfStack++;
} else if (topOfStack + 1 < maxSize) {
for (int n= maxSize - 1;n >= 0;n--) {
[Code] ....
I am trying to take physical print out for bill, But i am receiving some problems:
Java Code:
import java.awt.Color;
import java.awt.print.PrinterException;
import java.util.ArrayList;
import javax.print.attribute.AttributeSet;
import javax.swing.JTextArea;
import javax.swing.JTextPane;
public class Printme {
[Code] .....
But My Output is
What i have to do / learn to get the proper bill format ....
when do they get called?
from my code
class MyJava{
static { System.out.println("initializing..."); }
public static void main(String[] args)
{
}
}
i did get the "initializing..." string output, even though i didn't create any MyJava objects.
from this fact, i inferred that initializing blocks get called once when the program compiles.
am i right?
why the output is not giving the proper result? Is this a semantic error?
public class Programming1Practice {
/* testing out instantiation and object oriented programming */
public static class staticValues {
[Code]....
Okay so I need to be able to read a file and then be able to find the longest sequence of increasing numbers.
So if the file was this, (this is Ass1Q2_test4.txt)
97 47 56 36 60 31 57 54 12 55
35 57 41 13 82 80 71 93 31 62
89 36 98 75 91 46 95 53 37 99
25 45 26 17 15 82 80 73 96 17
75 22 63 96 96 36 64 31 99 86
12 80 42 74 54 14 93 17 14 55
14 15 20 71 34 50 22 60 32 41
90 69 44 52 54 73 20 12 55 52
39 33 25 31 76 45 44 84 90 52
94 35 55 24 41 63 87 93 79 24
the output should be,
(5,0) with cost 12
(6,0) with cost 14
(6,1) with cost 15
(6,2) with cost 20
(7,2) with cost 44
(7,3) with cost 52
(7,4) with cost 54
(6,3) with cost 71
(5,3) with cost 74
(4,3) with cost 96
Greatest path is of length 10.
Now, the code that I have works, kind of. Instead of recurring several times at each point, it only recurs once.
So say I'm looking at (1,1). With (1,1) being 57. The area around it looks like this.
97 47 56
35 57 41
89 36 98
Now when I look at it, there are several paths it can take. It can go 57, 97 or 57, 89 or 57, 98. However, I'm pretty sure that it just uses the first one that corresponds with the first if statement that is valid. So I start checking north of the value, then northeast, then east, then southeast, which at southeast is where I find my first greater than value. After it finds it's first valid number, it then continues from that number, instead of checking if there are other longer paths stemming from the original value.
In conjunction with that, you can see that the printout just returns all paths from each value. Which isn't what I want. I need a way to store the longest current path, then check each path after to see if it's longer. If it is, it's replaced, if not, it stays the same.
I've also attached Ass1Q2_test4.txt
import java.util.*;
import java.io.*;
public class MaxIncreasingSub {
[Code].....
I have to divide a text file into blocks of 128 bits. I think i must use the ByteArrayInputStream and ByteArrayOutputStream classes. is there any website showing how to user these two ByteArrayInputStream and ByteArrayOutputStream classes in detail. or it would be much better if you could show me a portion of the code.
View Replies View RelatedYou are given 2 files - "testcase.txt" and "validwords.txt".In testcase.txt, the sentences are written without any space inbetween/for ex: this is a sentence which looks ambigous.You are to insert a space at the proper place by breaking the sentence into correct words, ex o/p: this is a sentence which looks ambigous.validwords.txt contains all valid words (as 1 word per line). If you find a word that does not match, replace it with ####. After correcting
View Replies View RelatedI have to write a program that will read a picture and then print out the number of blocks inside it.
I have to read the picture as a binary matrix of the size r - c (number of rows times number of columns). The blocks are groups of one or more adjacent elements with the value 1.
- Blocks are built exclusively of elements with value 1
- Each element with value 1 is a part of some block
- Adjacent elements with value 1 belong to the same molecule.
We only take into account the horizontal and vertical adjacency but not diagonal.
INPUT:
In the first line of the input we have the integers r and c, separated with one space.
Then we have the r lines, where each contains s 0's and 1's.
The numbers inside the individual lines are NOT separated by spaces.
The OUTPUT only print the number of blocks in the picture.
Example:
INPUT:
7 5
01000
00010
00000
10000
01000
00001
00100
OUTPUT:
6
THIS IS WHAT I CAME UP SO FAR:
import java.util.Scanner;
class Blocks{
public static void main(String[] args){
Scanner sc=new Scanner(System.in);
char ch[][];
int rowNum=sc.nextInt();
int columnNum=sc.nextInt();
[Code] ....
Here's the code: it's while loop inside a for loop to determine the proper length of a variable:
for (int i = 0; i < num; i++) {
horse[i]=new thoroughbred();
boolean propernamelength = false;
while (propernamelength==false){
String name = entry.getUserInput("Enter the name of horse "
[code]....
I was just wondering what was going on here -- I've initialized the variable, so why do I get this message? (actually the carat was under the variable name inside the parentheses.
We have triangle made of blocks. The topmost row has 1 block, the next row down has 2 blocks, the next row has 3 blocks, and so on. Compute recursively (no loops or multiplication) the total number of blocks in such a triangle with the given number of rows.
triangle(0) → 0
triangle(1) → 1
triangle(2) → 3