I have an ArrayList, based on the class which stores cricket players, their names and runs scored.When I use the Collections.sort() method my arraylist is sorted alphabetically by forename.how to OverRide the comparing method to sort by runs, and thus the code I use to sort the list?
View Repliesthe clone method of the object class is protected, so therefore we have to override this method I understand this. What doesn't make sense to me is that the protected access modifier gives access to classes in the same package and subclasses. Isn't every single class we make a subclass of the Object Class?
View Replies View RelatedI read the following comment at stackoverflow.com. It is not clear to me why equals in the code below does not override - i looked up Object class equals() and the signature is same.
public class Foo {
private String id;
public boolean equals(Foo f) { return id.equals(f.id);}
}
This class compiles as written, but adding the @Override tag to the equals method will cause a compilation error as it does not override the equals method on Object.
I have some codes as below:
public class Hello
{
public static void main(String[] args) {
new Student().fun();
}
}
class Person
[Code] ....
Now the output is "Person". if i hide the "PRIVATE" in class PERSON, that is, method PRINT in class STUDENT override the same method in its father class, then the output is "Student". Why? I mean, how does the program know what PRINT method should be called?
I'm using "standard-kepler-SR2-win32-x86_64" and have installed "jdk-8u5-windows-x64".
But eventhough I can't override a methode like that "@override", it still says me:"annotations are only available, if source lever is 1.5 or greater".
Fine, therefore I installad "jdk-8u5-windows-x64", its the higest one on that oracle side, what else is needed?
I read this tutorial about overriding equal and hashcode method. [URL] ....
I understand how to override equal method, by overriding it, We can custom our compare. I also understand How to override hashcode, To make custom hash.
But still I can not understand why we do it? why if equal method override, we must override hashcode method too?If we don't what is the problem?
To honor the above contract we should always override hashCode() method whenever we override equals() method. If not, what will happen? If we use hashtables in our application, it will not behave as expected. As the hashCode is used in determining the equality of values stored, it will not return the right corresponding value for a key.
Is it the right reason in order to override:
Because when we customize equal method so it focus on special variables,We must change the hash code too in order to match with it, so hashcode also focus on those special variable.
Write TestCabAppointment,java class where you will instantiate new CabAppointment objects and read data from RandomAccessFile and create CabAppointment objects and save them in RandomAccessFile You may use FixedLengthStringIO,java class, ICabAppointmentRecord.java interface. Complete the ReadWriteRandomAccessFile.java
CabAppointment.java (this class extends Appointment class)
private int id;
private Address startAddress;
private Address destinationAddress;
private String terminal;
private String description;
[Code].....
I am trying to make a ChessBoard class composed of an array of JLabels inside a JPanel with a grid layout. I am also trying to override the getPreferredSize method so that the board will change size when I resize the main window (in another class in which I will instancize this class as part of a larger GUI). I got this kind of layout working before, but now I am trying to get it to work with multiple classes. However, after copying in the part of the previous code corresponding to the panel's layout, I am encountering some errors that I don't know how to solve. Specifically, when I try to override the getPreferredSize method, the compiler tells me "method does not override or implement a method from a super type, " and that it can't find the method "getPreferredSize"
Here's my code:
public class ChessBoard extends JPanel//the panel that this class extends is the boardHousing
{
//mental chess board piece array
Piece mentalBoard[][] = new Piece[8][8];
//actual GUI chessboard JLabel Array
static JLabel chessBoard[][] = new JLabel[8][8];
[Code] ....
I would just think that I was overriding the method incorrectly, but the weird thing is that I got that specific section of code to work before -- the only thing different now is that there are multiple classes, so my ChessBoard class itself is extending JPanel.
I am getting incombatable types, I do not know why I am getting them..why I am getting the error?
The Error I am getting:
stringSort.java:26: error: incompatible types
if(myArray[j].compareToIgnoreCase(myArray[i].toString())){
^
required: boolean
found: int
*/
[code]....
I'm trying to make a selection sort method that will sort a list of Strings alphabetically.
I have a test list of Strings like so:
Joe, Steve, Oscar, Drew, Evan, Brian, Ryan, Adam, Zachary, Jane, Doe, Susan, Fred, Billy-Bob, Cindy, Mildred, Joseph, Hammer, Hank, Dennis, Barbara
However, whenever I run the method, the element that should go last, Zachary, in this case, ends up getting moved to the front for some reason. I'm not sure why.
I tried changing what the first element was initialized to, to the variable i as that would logically work as well, but it ends up missing the first element in the list.
Java Code:
public static void selectionStringAscendingSort (String[] words){
int i, j, first;
String temp;
for ( i = 1; i < words.length; i++ ) {
first = 0; //initialize to subscript of first element
for(j = i; j < words.length; j ++){ //locate smallest element between positions 1 and i.
if( words[ j ].compareTo(words[ first ]) <0 )
first = j;
}
temp = words[ first ]; //swap smallest found with element in position i.
words[ first ] = words[ i ];
words[ i ] = temp;
System.out.println(Arrays.toString(words));
}
System.out.println(Arrays.toString(words));
} mh_sh_highlight_all('java');
I have a question about selection sort. If I had an array of numbers, 1 2 3 4 100 0, and used the selection sort method (below) on the array,would the 0 slowly work it's way down to the end?
Nest loop = full rotation of nest loop
Nest loop 1: 1 2 3 4 100 0
Nest loop 2: 1 2 3 4 100 0
Nest loop 3: 1 2 3 4 100 0
Nest loop 4: 1 2 3 4 100 0
Nest loop 5: 1 2 3 4 0 100
Nest loop 6: 1 2 3 0 4 100
etc.
METHOD:
static void selectionSort(int[] arr){
int n = arr.length;
for(int i = 0;i<n;i++){
int min = i;
for(int j = i+1;j<n;j++){
if(arr[j]<arr[min]){
min = j;
}
}
int temp = arr[i];
arr[i] = arr[min];
arr[min] = temp;
}
}
im 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 ??
How would I modify this version of a selection sort into a recursive method?
public static void selectionSortRecursive(Comparable [] list, int n)
{
int min;
Comparable temp;
for(int index =0; index < n-1; index++){
min = index;
[code]....
I have been looking around and I cannot seem to find which algorithm java uses for its sort method. Merge, sort etc.
While I am on the topic BinaryTree is a balanced heap right?
Are there any libraries for depth or breath first search?
Is the ArrayList a double linked list?
I'm doing an exercise we're you're supposed to sort strings in alphabetical order, without importing anything , not using the Arrays.sort() method.
I think I got the method down partially right, or it is on the right track, but it is completely not being applied to my answer. All it prints out in the console is the actual String array twice, without sorting anything.
public class arrayofstrings {
public static void sort(String[] a) {
String temp= "";
int min;
int i= 0;
for (int j=0; j<a.length-1; j++) {
[Code] ....
Java Code:
import java.util.ArrayList;
import java.util.Random;
public class NumSorting {
public static int numOfComps = 0,
numOfSwaps = 0;
public static void main(String[] args)
[Code] ....
What is wrong with my code in this sorting program? It won't copy the random generated numbers to the sort method. How to get the random generated numbers to copy to the sort method. Below is what the program is displaying.
Original order : 3 2 5 4 1
Selection Sort
Original order:
[I@7a84e4
Number of comps = 10
Number of swaps = 0
Sorted order : 0 0 0 0 0
So I'm trying to implement a quick sort method for an ArrayList of Strings and right now I'm getting the compiler error message: Exception in thread "main" java.lang.OutOfMemoryError: Java heap space. I don't know what that error means nor how to fix it. I've marked in my code where the error seems to be occurring.
import java.util.ArrayList;
public class quickSort
{
// constructor
public quickSort()
[code]....
This time I am having difficulties with selection sort method, but not with the method itself (I think). So I need to sort an array and return the result of each step.
This is the main code:
public class Functionality {
public static int[][] selctionsort(int[] a) {
for (int i=0; i<a.length; i++) {
int least = i;
for (int j=i+1; j<a.length; j++)
[Code] ....
And this is the Test folder:
import static org.junit.Assert.assertArrayEquals;
public class PublicTests {
public static void main(String[] args) {
int[] a = new int[] { 35, 7, 63, 42, 24, 21 };
int[][] b = new int[][] { new int[] { 7, 35, 63, 42, 24, 21 },
[Code] ....
Now I am not sure what should I write in return since the 2nd (test) project has int[][] and in my main project I am working with int [].
I'm having trouble with sorting Strings- 3 strings inputted by user, and I would like to output them in alphabetical order. I've used the str.compareToIgnoreCase method, and then I've tried to loop them through a series of if/ else statements. Everything I've been able to find online (including the forums here) has suggested to use the Comparator class, or to put the strings into an array, and sort list- I really would like to stick with just the String class, and its methods .
The program itself works and compiles, but I am getting logic errors that I have been unable to solve. I'm using IntelliJ Idea, and I've ran it through the built in debugger, about 100+ times (not exaggerating, lol) just to see what it's doing in particular scenarios. For instance, I can get c, a, b, to print out as a,b,c correctly, but a,b,c, will print out as b,a,c.
For me this is kind of like a Sudoku puzzle, or a Rubik's cube! Each time I fix one scenario, it breaks another one, so I don't know if there's a(logic) solution to fix all possible scenarios (abc, acb, bac etc... to all print abc) or if possibly I just need more if statements. I've only pasted in the area where I'm having problems (the if statements). I'm a big fan of the "Next Line" syntax.
(Note: please assume the non relevant content- import Scanner class, main method, etc... I didn't want to paste the entire program.)
System.out.println("Enter the first statement: ");
//input.nextLine();
string1 = input.nextLine();
System.out.println("Enter the second statement: ");
string2 = input.nextLine();
System.out.println("Enter the third statement: ");
string3 = input.nextLine();
[Code] ....
I'm learning about inheritance and part of my problem is to create an Order with methods, then an UpdateOrder where the total price is changed by adding four dollars to it, and then a main method displaying a few orders. I've copied all three below in order. My question is when I run the program it will display the totalprice() first for the second order followed by name, number, etc.what you override always displayed first regardless of the order you put them in? (The issue is at line 31 on the third code.)
import javax.swing.JOptionPane;
public class Order { //superclass
private String customerName;
private int customerNumber;
protected int quantityOrdered;
protected double unitPrice;
protected double totalPrice;
[code]....
I am wanting to override certain methods in some Minecraft class files, and tell those class files to use code from my class files.
And no, I don't mean extend a class. When I try to extend from the main Block.Class, it makes that file as another block file for the game, or something.
So like, I want to tell the main file that handles block registries to use the code from my class file to register my custom blocks to the list of blocks, but without modifying that main block file.
Is this even something that's possible?
Also, I know that the way a file is named affects the loading order. My class files would be named using symbols to make it load right before the class file I want to override.
We have developed a theme called default.css that is extending of the default caspian.css. What we want to do is offer users the ability to override values from default.css to change colors etc. How can that be done?
View Replies View RelatedI have a little application that I made, it requires that I save data to a file in data/coins.cdp. When I run the application with java myProg in the terminal everything is correct, when I create the executable jar and run java -jar myJar.jar or ./myjar.jar everything also works. Even if I copy the jar to a different location, and run it through the terminal, it still works fine. Things get weird through when I copy the jar to a new location and double click on it, because then no folder gets created and no file is written.
Why is that?
I'm using the book "How to Program in Java 9th Edition". The following is code from that book. I'm using eclipse. When the code is run the images are not showing up in the frame. The images are located in the directory with the java file and I have tried using the fully qualified image locations with no success. I've looked around on the web but can't see any reason why this code won't work. The code compiles and no errors are reported.
// Fig. 9.13: LabelDemo.java
// Demonstrates the use of labels
package Fig9_13DisplayTextImagesWithLabels;
import java.awt.BorderLayout;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JFrame;
public class LabelDemo
[code]....
I was wondering if their is an easily explainable way to convert a jar for a text-based game that runs off the command prompt into a executable. I would guess there probably is not and the game would have to run off of completely different commands, but I thought it couldn't hurt to ask.
View Replies View RelatedHow do I record the number of times all runs of heads occur. Ex.
Length Number of runs of heads
1 --------------------3
2 --------------------2
3 --------------------0
4 --------------------1
public static void main(String[] args)
{
int [] coinToss = new int[TOSSES];
int longestRun = 0;
int run = 0;
for(int i = 0; i < coinToss.length; i++)
coinToss[i] = toss();
[Code] .....