Difference Between ArrayList And Vector Class
Jun 26, 2014What is the difference between ArrayList and Vector class
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Difference Between LinkedList And ArrayList
Feb 19, 2014I have just begin to understand collections in Java. I read about the differences between LinkedList and ArrayList but have several doubts on it. I have mentioned them below
1) Why retrieving in ArrayList is faster then LinkedList?. Since both have the get method how does performance differ?.
2) How does re-sizing happens internally in ArrayList when a item is added or removed?. How slow this is compared to the pointer re-shuffling in LinkedList when a item is added or removed?.
Difference Between Hashmap Linkedlist And Arraylist?
Jul 10, 2014What are the difference between hashmap, linkedlist and arraylist ... when they are used and why?
View Replies View RelatedDifference Between A Class And Object
Jan 29, 2014I have finished a Java 101 class but the most we did was create a gui for a timer program. I figure I need more training and every book I pick up wants to teach me hello world and the difference between a class and object again.
View Replies View RelatedDifference Between Abstract Class And Interface?
May 18, 2011Difference between Abstract class and Interface??
View Replies View RelatedDifference Between Instance And Class Variable
Mar 25, 2014I'm having trouble to fully understand the difference between instance and class variables.
I though it was all about the static, i.e:
int age; // instance variable
static int age; // class variable
What's behind this?
Difference Between Extending JFrame And Just Creating One In The Class?
Oct 18, 2014What is the difference between extending JFrame in one class and simply constructing a new JFrame object in that same class? What benefits do I have with each solution, providing I want to use that class to create the GUI. Is it the same or are there differences rather than not having to reference to a new JFrame to be able to use its functions?
View Replies View RelatedDifference Between Explicit In Class Initialization And Non Static Instance Initialization
Dec 20, 2014 I come from a C++ background and I recently started learning Java from "Thinking in Java" 4th Edition by Bruce Eckel.What's the difference between:
// explicit in class initialization
// saw this on page 126
class A {
}
public class B {
A obj1 = new A();
A obj2 = new A();
}
and
// non static instance initialization
// saw this on page 132
class A {
}
public class B {
A obj1;
A obj2;
{
obj1 = new A();
obj2 = new A();
}
}
Accessing ArrayList Of Another Class
Oct 19, 2014What I want to do is this, this is my first class:
public class Footballer {
int goals;
String surname= "";
String team="";
private static int counter=0;
private int dres;
}
(this is just the header of the class... And this is my second class, which contains an ArrayList of the first class:
public class FootballTeam{
String teamname="";
String league="";
ArrayList<Footballer> f;
}
And this is my third class which contains an ArrayList of the second class:
public class FootballLeague{
String leaguename="";
ArrayList<FootballTeam> ft;
}
What I want to do is, know how many of footballers are there in the league? Meaning how many of "f"s are in the "ft"... I remember from C++ it was easy, you just did it something like this: ft.f[i]; (where i is a position), then you'd go through each of them, if you wanted to do something with them, or just ask for it's length, if you needed to know how much footballers are there.
I'm trying this method to get the size of the array in the 2nd class, from the 3rd class (containing an ArrayList of classes of 2nd class, but no luck:
int counter=0;
for(int i=0;i<this.ft.size();i++) {
counter+=this.ft[i].f.size();
}
I'm getting this: Array required, but ArrayList<FootballTeam> found ---
Value Inherited Between Different Arraylist Of Same Class
May 14, 2014I have extracted relevant parts of code and outputs, this is the only relevant code for this problem. There is a basic class called SalonData, which contains the fields refereed to. Original data rs. is obtained from an SQL extract, that is populating correctly.
public ArrayList<SalonData> salons=new ArrayList<SalonData>();
ArrayList<SalonData> loc2=new ArrayList<SalonData>();
SalonData salon=new SalonData();
salon.CardRecordID = rs.getString("CardRecordID");
salon.SalonName = rs.getString("Name");
[Code] ....
Printed results after this code is run;
Salons
2022XYZ PTY33 Smith Street319603 9773 2000
loc2
2022XYZ PTY33 Smith Street319603 9773 2000
The code was inteded to populate the phone number in arraylist "loc2", but based on the code, the phone number in arraylist "salons" for Location 2 should still be blank. Question is how did the phone number for this customer in arraylist salons, for Location 2, get populated?
How To Add And Remove From Arraylist Through Different Class
Mar 13, 2014Right now i am working on some java using BlueJ and trying to insert and remove data from an arraylist through a public class or from a new class.
I want it to have it as like a database were you can add and remove data but have a limit of storing.
Accessing ArrayList Of Another Class
Oct 19, 2014What I want to do is this, this is my first class:
Java Code:
public class Footballer {
int goals;
String surname= "";
String team="";
private static int counter=0;
private int dres;
} mh_sh_highlight_all('java');
(this is just the header of the class, just how it looks)...
And this is my second class, which contains an ArrayList of the first class:
Java Code:
public class FootballTeam{
String teamname="";
String league="";
ArrayList<Footballer> f;
} mh_sh_highlight_all('java');
And this is my third class which contains an ArrayList of the second clas:
Java Code: public class FootballLeague{
String leaguename="";
ArrayList<FootballTeam> ft;
} mh_sh_highlight_all('java');
What I want to do is, know how many of footballers are there in the league? Meaning how many of "f"s are in the "ft"... I remember from C++ it was easy, you just did it something like this: ft.f[i]; (where i is a position), then you'd go through each of them, if you wanted to do something with them, or just ask for it's length, if you needed to know how much footballers are there.
Using ArrayList In Another Class (Main)
Mar 27, 2014If I declare and ArrayList as follows
"public static ArrayList<Media> mediaList = new ArrayList<Media>();"
How can i access it in another class (main class)?
package Projekt;
import Projekt.Media.rating;
public class MainTest {
static MediaHandler myreg ;
public static void main(String[] args) {
myreg.addMovie(title, playTime, year, seen, directory, path, rating.four, quality, subtitles, language, writer);
}
}
I also have the variables declared but didn't include them for readability.
Vector Pair In Java
Mar 29, 2015I want to convert this following piece of c++ code into java...but i cannot find suitable substitute for vector pair...what shall i do?
#include <cmath>
#include <cstdio>
#include <vector>
#include <utility>
#include <iostream>
#include <algorithm>
using namespace std;
bool compare_polar (int x1, int y1, int x2, int y2) { // if p2 > p1 return true
[Code] .....
Looping Through Objects Vector
Nov 11, 2014I'm having some issues, trying to solve this problem in java. I want to print some election results, and i have to loop through a vector of objects and retrieve the partial sums of each party's seats for each constituency and the national results for each party. For now i can print the results per contituency, but i'm having problems in getting the national results. Like, adding the seats for labour party in Constituency A and B and C, etc, and print the sum. And do the same for conservative party.
This is what i have.
Java Code:
while (i < h.geral.size()) {
show += "Constituency - "
+ ((Party) h.geral.elementAt(i)).getConstituency() + "
[Code] .....
Sorting ArrayList Of A Class According To A Field
Oct 13, 2014we have an Arraylist<Tweet>, and this class is defined as followe: public class Tweet implements Comparable<Tweet>, Serializable. now if we implement the method comparteTo, then will it be sorted automatically? I want to sort this array by any insert.
View Replies View RelatedError - ArrayList Has Private Class
Jan 30, 2015Java Code:
import java.util.Scanner;
import java.util.ArrayList;
public class Problem1
{
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
ArrayList<String> list = new ArrayList<String>();
[Code] ....
There is an error and says that my ArrayList has private access. I can't figure out how to fix it.
The code runs but when I enter "Quit", the program just stops. The arraylist isn't printed out?
Swing/AWT/SWT :: Vector Is Used In ComboBox Model?
Sep 23, 2014I understand how vectors work I'm currently using one to store my id's from my txt file but how do you put them in a defaultComboBoxModel?
DefaultComboBoxModel defaultComboBoxModel = new DefaultComboBoxModel();
//declare a vector object that will hold a string (only thing that works with comboboxmodel
Vector<String> myVector=new Vector<String>();
//try statement
try{
FileReader fr = new FileReader(file);
[Code]...
Any example of how a vector is used with a defaultComboBoxModel so I can then use that to populate my JComboBox?
Accessing Vector Variables With Scanner?
Jan 26, 2015When I input "the" or "and" I always receive "its not here" as the output. Why is this? I also tried printing the values of v.get(i).other and the system printed null twice.
public class Translator {
public String other;
public Translator(String x) {
x = other;
[Code].....
Converting From A Vector Containing Big Decimal To A Float
Mar 13, 2015I'm having extreme difficulty in working with a Vector storing a column with a BigDecimal value, and converting that single value into a float. I'm not sure why the code was written this way, but basically, I'm working with something called a vector that has a single Big Decimal value/column (not sure what the correct terminology is), and I want to store that value in a float variable called "dp". However, I don't know how to convert from the Big Decimal to a float.
Code is below:
String s = "";
sql = "SELECT DiscountPercentRate FROM Attendees WHERE AttendeeId=" + attendeeId;
Vector v2 = sqldb.getResults(sql); /*I know that sqldb.getResults(sql) returns a vector with a single BigDecimal column of 15.0, in the test example I'm using*/
if (!v2.isEmpty()) {
Vector data2 = (Vector)v2.elementAt(0);
if (!data2.isEmpty())
[Code] .....
In case you're wondering what the sqldb.getResults() method looks, like, here's a snippet of it - There's an else statement that triggers in my case, adding a BigDecimal column to a vector, and returns that vector.
Vector v = new Vector();
...
else {
BigDecimal bd = rs.getBigDecimal(i);
vCols.add(bd);
}
v.add(vCols);
...
return v;
How can I take the single result of my SQL query in that Vector/Big Decimal thing, and turn that result into a float value?
Writing / Reading To And From Vector In JAVA
Nov 20, 2014I have a project where I am required to read and write a vector of bank account objects and I am struggling with this concept. I was able to figure it out when the accounts were not stored in a vector but now that I am dealing with vectorsThis is my best attempt. Even though I know it's wrong, what I am trying to do.write/read methods in main:
public static void readTrans()
{
textArea.setText("");
chooseFile(1);
try
{
FileInputStream fis = new FileInputStream(filename);
ObjectInputStream in = new ObjectInputStream(fis);
for (int index=0; index != fileIndex; index++)
[code]....
Swing/AWT/SWT :: Adding Arraylist To Jtable In Another Class
Jan 23, 2015I'm trying to fill my jtable with an arraylist. The problem is the jtable is in an extended class and the arraylist in the mainGUI. Now how can I fill the jtable with the arraylist?
That's the arraylist in my MainGUI
BufferedReader in = null;
ArrayList<String> data = new ArrayList<String>();
try {
in = new BufferedReader(new FileReader("1.dat.txt"));
String str;
while ((str = in.readLine()) != null) {
data.add(str);
[Code] ....
How To Create Insertion Sort Method For A Vector
Jun 9, 2014im trying to create an insertion sort method for a vector. I know how to insertionsort for an array, but for a vector im having problems
Source code:
PHP Code: package test;
import java.util.*;
import java.io.*;
public class LinearSearch {
public static void main (String[] args) {
Vector myVector = new Vector();
[Code]...
I'm getting errors at lines 38 and 39 "Left-hand side of an assignment must be a variable". "Syntax-error(s) on token(s) misplaces contructor(s)". How can i fix them ??
Create Mathematical Vector Of D Dimension Initialized At 0
Nov 14, 2014class GVector {
// TODO: declare a private array to save the vector coordinates
// Creates a mathematical vector of d dimensions, initialized at 0
public GVector(int d) {
// TODO: implementation
[Code] ....
I'm confused with what type of array I need to use to save the vector coordinates and what to put in Gvector. Is it a constructor?
Populating ArrayList Using Scanner Class Logic Error
Sep 12, 2014My code runs and populates an arraylist. However my break statement, while stopping the loop ends up being added to the arraylist. And I'm not sure how to fix this error.
public static void main(String args[]) throws Exception
{
// declaring variables
String input = "";
// creating array list
ArrayList<String> nameList = new ArrayList<String>();
[Code] ....
Random Color Ball And Move Bottom Bar Vector?
Feb 20, 2014I created this simple vector java program where ball falling and when collide with the bar below, the ball stops.
I need to make the ball falling randomly from different direction and also need to make the bar move left right using keyboard arrow.
Code:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
//using timer to increase the counter
[code].....