Design Patterns And Java Algorithms
Nov 22, 2014
I've looked over the concepts of Java programming, tested them in code and i understand most of them. I have a problem when i need to make harder programs , this might be because i dont know design patterns and algorithms.I'm curious what a entry level programmer needs to know to get a job in the field. Right now i was thinking i need to know:
1. The way all big concepts work and most of the keywords.
2. Design patterns.
3. Algorithms.
what i actually need to know for an entry level job and can you tell me which design patterns and algorithms are a must know for that first job. Considering i might have financial problems in the near future this is not a theoretical question, i really need to know what i need to learn in the next 2-3 months to get an entry level job down.
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May 9, 2015
we have been given a scenario to design a system in which we have to make the class diasgrams. however we have to use appropriate patterns that match the scenario.
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Apr 30, 2014
Design Patterns are one form of reuse. so is inheritance. what are the similarities and difference between them?
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Feb 3, 2015
When it comes to Java EE I see many developers having trouble with the usage of transactions and exceptions and when to use what.
I see a full chapter of RESTful Web Services, but do you also relate these Web Services to their counterparts (SOAP Web Services)?
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Feb 20, 2006
what are design patterns ? what is the difference between design patterns and frameword ?
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Nov 16, 2014
My assignment was to create a simple form that demonstrates the use of the factory and singleton design patterns. "Use the Factory pattern to ensure that each form input consists of a text label and a textfield. Use the Singleton pattern for the submit button. When the submit button is clicked, a pop-up should show all the information that was typed into all of the form fields."
I used JFrame to create the form without the design patterns and I although I get the desired result, I'm not quite sure how I can integrate the design patterns into the code I wrote. The example I have to go off uses shapes, not text fields so I think that's why I'm not quite clear on how to approach this.
Here's my code so far:
import javax.swing.event.*;
import javax.swing.*;
import java.awt.*;
[Code]....
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Nov 20, 2014
My assignment was to create a simple form that demonstrates the use of the factory and singleton design patterns. "Use the Factory pattern to ensure that each form input consists of a text label and a textfield. Use the Singleton pattern for the submit button."
Here's what I have:
Form.java file
interface Form {
public void getFormField ();
}
Name.java file (I have a similar files just like this for Address.java, City.java, State.java, Zip.java and Phone.java)
import java.util.Scanner;
class Name implements Form
[Code] ....
It compiles at the moment but I get a null pointer exception in the main method of the FormFactoryDemo file.
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Nov 25, 2014
how to create new nodes with this values below and insert them in the following order.
55, 2, 76, 2 , 9, 1, 90, 43, 5, 23, 86, 3, 321, 4, 32, 66, 99, 12, 21
I have one Insert method One traversal method, with a post-order( I don't know if I need to use pre-order, I'm trying to use a very poor hash function ℎ(xx)= √xx xKK mod 2 where xx is 2012559 and KK=3.14. If ℎ(xx) = 0, my traversal method is pre-order, and if ℎ(xx) = 1 my traversal will be post-order.I have 4 separated classes, Tree.java, Node.java, Test.java and traversalType.java
package BST;
public class Node {
int data;
Node leftChild;
Node rightChild;
public Node(){
[code]....
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Nov 25, 2014
how to create new nodes with this values below and insert them in the following order.
55, 2, 76, 2 , 9, 1, 90, 43, 5, 23, 86, 3, 321, 4, 32, 66, 99, 12, 21
I have one Insert method One traversal method, with a post-order( I don't know if I need to use pre-order, I'm trying to use a very poor hash function ℎ(xx)= √xx xKK mod 2 where xx is 2012559 and KK=3.14. If ℎ(xx) = 0, my traversal method is pre-order, and if ℎ(xx) = 1 my traversal will be post-order.
I have 4 separated classes, Tree.java, Node.java, Test.java and traversalType.java
package BST;
public class Node {
int data;
Node leftChild;
Node rightChild;
public Node(){
[code]....
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Aug 29, 2014
I know nothing about algorithms and data structures.Is there any good books where I can start learning it.Should I also learn advanced mathematics?
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Jul 11, 2014
I am designing an application I want to know what are the best technology Like Java FX for front end design?
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Jun 16, 2014
Basically I have to enter 5 numbers that I put through a loop and they print the star * depending on the number.An example would be this 5:*****. However, my codes prints out 5:*; 5 times. How to correct my code
Java Code:
import java.util.Scanner;
public class IntegerOutput
{
public static void main( String args[] )
{
Scanner input = new Scanner( System.in );
int num1;
int num2;
int num3;
int num4;
int num5;
[code]....
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Feb 5, 2015
I have three sorting algorithms in which I must count the number of swaps/copies and comparisons. I am meant to only count the swaps and comparisons that involve anything other than indexes as they are too fast to really matter (according to the professor). My counters are in the right position or not. I keep coming up with swaps/comparisons that don't necessarily match the formulas I'm finding for best/worst case. Makes me think that my counters are somehow out of place or that I don't have enough of them.
Insertion Sort:
public class InsertionSort {
public static void insertionSorter(int[] array) {
int firstValue; // first value in array
int scan; // scan array through the array
int moves = 0; // number of moves
[Code] ....
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Apr 26, 2014
Here is an example of a GUI. Is it possible to make this kind of a thing using Java Swing? Is it possible to have a picture on the entire background of the JFrame, and then other Swing components like buttons, labels etc. sitting on it?Is it possible to have action listeners behind pictures? In other words, they will behave like buttons: the user clicks on them and they do something.
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Mar 6, 2015
The idea I'd like to present, concerns the correction of "designer" drawings - those done by the design consultants - against "site/construction" drawings - them being used on site by the workers to build the project itself.
This is normally a laborious process, involving being sat at a desk with two large folders, checking each detail and measurement against the design drawing.What I'd like to present is an idea, where the co-ordinates of the design or "mother" drawing, are transferred into a usable Java program, and they could be then used to ensure correct dimensions have been applied by the the sub-contractors in their "construction" drawings.Like I said, this can normally be a process of days for a site engineer to check - process known as "QA, quality assurance".
Basically, I just need to make a presentation of having a genuine interest in Software Design and Development. It could be applied in a range of areas in terms of construction site application - checking drawings, writing up work orders, dig orders etc - but the principle of having the co-ordinates of the mother or "design" drawing scanned into an array in Java as a means to output those site drawings/orders etc, applies to each potential application.
So - in short - and not looking for crystal clear detail, just general pointers - what programs or methods could transfer a plethora of co-ordinates from a design program like Auto-Cad, to a Java program, where I assume I would then be using a program containing a complex series of loops to ensure the correctness of the derived "construction" drawings; derived from the "mother" or designer drawings, that is.
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Jun 1, 2014
I am planning to develop an application that does the following:
1) Receiving an audio streaming from a shoutcast server
2) Decode and push it throught producer to a shared buffer
3) Share audio data to as many consumers are interested to this feed.
What is the best practive for doing this? I tried several things without success.
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Feb 9, 2015
i want to use nested loops to print patterns but i cant seem to make a pattern that will look like V and K this should be the outcome.
* *
* *
* *
* *
*
@ @
@ @
@@
@ @
@ @
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Feb 4, 2015
My question is regarding the the Inversion of Control (IoC) and Dependency Injection (DI) patterns, when learning about Spring i saw that people keep talking about Ioc and Dependecy Injection like if its the same thing!
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Mar 7, 2014
Write a method to print each of the following patterns using nested loops in a class called PrintPatterns. The signature of the methods are:
public static void printPatternX(int size) //'X' from 'A' to....., size is a positive integer.
#
##
###
####
#####
######
#######
########
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Mar 23, 2015
I have to make a pattern that is of a diamond shape such as this:
Java Code:
1
1 2 3
1 2 3 4 5
1 2 3
1
mh_sh_highlight_all('java');
I wrote this (for the variable name, this is just a small part of my program and I'm trying to get the pattern right so I didn't mind my variables at the moment):
Java Code:
public class NewFile{
public static void main(String []args){
int k = 0;
for (int i=1 ; i<=5 ; i++) {
{ for (int h=2 ; h >= i ; h--)
[Code] ....
My output is the following:
Java Code:
1
123
12345
1234567
123456789
mh_sh_highlight_all('java');
I realize I should divide the code into a lower and upper triangle using two loops. However, I don't know how to break the first part. I did find the "trend" but I don't see how to implement it.
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Oct 2, 2014
I need to make a program that does stripes, checkerboard, and double diagonal. I can not get the stripes to work?
import java.util.Scanner;
public class AsciiArt {
public static void main(String[] args){
int pattern;
Scanner input=new Scanner(System.in);
System.out.println("Choose one of the following patterns by pressing the corresponding number");
System.out.println("1) Stripes");
[Code] ....
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Mar 29, 2014
design a class to conduct a survey of three hospitals. you want to know how many sectors (eg operation, children, gastronomic) each hospitals have, and how many doctors there are in each sector.
what is the process of class design?
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Jan 11, 2014
I was reading head first java and the author told to read head first design pattern next.
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Mar 31, 2015
I have done this a few times but I want to make sure I am doing it correctly. In other words creating a clean understandable program. Instead of posting code I will just talk about this is my plan:
Create a model (getter and setters)
Create a view (via swing)
Create a controller (pass the model and view in the parameter)
Database DatabaseConnection:
Use the singleton pattern
Database:
Create an interface called Database with all the queries I will need (insert, delete etc)
Create a class called DataBaseDAO and implement the interface database and get an instance of the DatabaseConnection.
Tying it all together:
In the controller should I use the "new" operator and create a new database class or extend the database class? I am thinking I should not do it in the controllers constructor but make a field if I use the "new" operator like:
private Database db = new Database();
Create a class called App
Create a new Model
Create a new View
Pass the view and model into the controllers parameter.
Am I on the right track? Is this messy? Is there a better way of doing it?
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Jul 17, 2014
I have a class as shown below. This class has a method addFilter with 2 parameters (type String and type Command1 )
public class Command1 {
public StringBuffer addFilter(String query, Command1 dataBase) {
//concrete implementation
return query;
}
}
I have another class Command2. Here I need a similar method. The only difference is in the type of parameters passed. (type String and type Command).
public class Command2 {
//TO DO:
public StringBuffer addFilter(String query, Command2 cmd) {
//concrete implementation
return query;
}
}
I have started by using Interface
public interface Helper {
public StringBuffer addFilter(String query, XXXXX parameter2);
}
I would like the classes Command1 and Command2 to implement the interface Helper and override it these two public classes.
However my problem is in dealing with the 2nd parameter. Am I right in my approach? How do I handle this issue?
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Mar 27, 2015
I need selecting which design pattern to use in my case.
I am creating a list of objects "items" to be presented in a list for the user to choose from, all objects have a title and a check box. Some objects have additional textbox for user input, some objects have additional image for illustration, and some objects have additional textbox and image as well.
I read and saw online videos but not sure if my selection "Factory Design Pattern" is the best match.
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