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?
the 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'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 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 Replies View RelatedI 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.
Here is the java code that i compiled on eclipse but each time i run it i am getting different sequence of output !!
What I did is that my main() calls a function m1() which calls a function m2() which throws an exception back to m1() which throws exception back to main().
public class ClassB {
public static void main(String[] args) {
try {
m1();
} catch (Exception ex) {
ex.printStackTrace();
[Code] ....
The output is as shown in screenshots at different times :
SCREENSHOT 1:
SCREENSHOT 2:
SCREENSHOT 3:
How is this possible ??
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] ....
I have wrote the necessary program for the class which was : Modify the customer class to include changeStreet(), changeState(), and changeZip methods. Modify the account class to include a changeAddress() method that has street city and zip parameters. Modify the Bank application to test the changeAddress method.
The problem arose when I went to test it. For some reason when it asks "Would you like to modify your account information? (y/n)" it will not allow the user to input anything and thus test the class. Here is my code
Class Customer
import java.util.*;
import java.io.*;
public class Customer {
private String firstName, lastName, street, city,state, zip;
[Code] ....
For the below program what are the default values passed by the JVM in order to call main() method
class program
{
public static void main(String[] args)
{
System.out.println(args[0]);
System.out.println(args[1]);
}
}
One of the random number generators in Java extract the higher-order bits of the random number in order to get a longer period.
I'm not sure if I understand how this is done. Suppose that the random number r = 0000 1100 1000 1101. If we extract the 16 most significant bits from r; is the new number r = 0000 1100 or r = 0000 1100 0000 0000?
Any link to the accurate explanation of binary trees in java?
View Replies View RelatedI'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 an ArrayList of employee and ArrayLsit of bosses, and I want to keep those people in a temporary ArrayList , then ordain alphabetically by name, to sort I use the interface comparator.
The problem comes when I will order 2 ArrayList(workers and bosses), because every time I call I use these functions or not is ordered (sortByNameAlphabetical())
public class Employee {
private String name;
public String getName() {
return name;
}
@Override
public String toString() {
return name ;
[Code]...
I came across this code which proves that variable initialisation occurs before even constructors are called.However, I am confused over some things.
Firstly, from my understanding, when a new House object is created in this line House h = new House(); , the no-arg constructor of the House class is called.
Since the no-arg constructor House() is called, why are all the creation of Window objects being run first ? Shouldn't Java jump straight into the no-arg constructor House() ?
class Window {
Window(int marker) { System.out.println("Window(" + marker + ")"); }
}
class House {
Window w1 = new Window(1); // Before constructor
House() {
// Show that we’re in the constructor:
System.out.println("House()");
w3 = new Window(33); // Reinitialize w3
[code]...
im new to java and i wanna make a program using java that can add order entries for a restaurant but how to... i was hoping something that would ask to person to input one or two items and before it calculates the total amount to be paid it will ask the guy who inputs the amount whether or not there are additional orders or not before it prints out the total amount... I am pretty sure it will need an if-else statement..
import javax.swing.*;
import java.util.Scanner;
public class OrderCalc {
JFrame.setDefaultLookAndFeelDecorated(true);
JFrame aFrame = new JFrame("OrderCalc");
aFrame.setSize(500,250);
aFrame.setVisible(true);
[code]....
I'm learning the swing options of Java, and my first exercise was the typical Chat Room. I got everything right: TextField, TextArea, the jpanel at left side and the buttons inside of it. BUT I can't order the 2 buttons (1 north, 1 south). I've already looked for answers, but didn't find anything and I tried to asked the teacher, but she was too lazy to look for the error. Here is my code:
f=new JFrame("Chat Room");
b1=new JButton("Send");
b2=new JButton("Emoticons");
public void showWindow(){
p1=new JPanel();
f.getContentPane().add(p1,BorderLayout.EAST);
p1.add(b1,BorderLayout.NORTH);
p1.add(b2,BorderLayout.SOUTH);
}
I am unsure of something. In the following class, which is read first; the static field or the main method?
class Test{
static int a = 3;
public static void main(String args []) {
//some code}
}
I put some code in Eclipse and have tried to look at the hierarchy. It would point to all static fields being initialized in order from top to bottom, including the main method.I had thought that the main method was always the first thing in a public class to be initialized, regardless of where in the code it resides. Am I reading the Eclipse hierarchy wrong? I find Eclipse very difficult, especially since I typically code in Textmate. I just want to see how my code is operated upon,
This is how the for loop works for the row,right?
for(int i=array.length-1;i>=0;i--)
{
}
I want to know how the for loop works for the column?
This is what I have to do:Write a program that takes a string of someone's name and prints it out last name first. Your program must use pointers, not array subscripts. You may use the available string manipulation functions if you find an opportunity.
Example:
"George Washington"
"Washington, George"
I am not sure how to reverse the name, I have been looking in my textbook and online and cannot figure it out. This is what I have put together so far, it does not run. At the end it says unnecessary return value.
import java.util.*;
import java.util.Scanner;
public class Test {
public static void main ( String [] args ) {
Scanner sc = new Scanner(System.in);
System.out.print("Enter name: ");
String name = sc.nextLine();
String lastname = "";
String firstname = "";
for(int i = 0; i < name.length(); i++) {
if(name.charAt(i) == ' ')
I am trying to sort an array that I have by alphabetical order but I am having problems. Firstly the code that I have used to sort the array may not even do what I need but havn't got far enough to test it yet so go easy on me . I have read in some places when searching how to do this that I would have to create my own bubble sort in order to achieve this but I was hoping that Java had a built in sort method/function. Secondly I lack the knowledge in java to be able to assign an existing array or even a variable to the newly sorted array as I need the unsorted version with the original name and the newly sorted version as another.
code (This is not all of the code, I decided to include only what I thought was relevant):
import java.util.Arrays;
public class Sentence {
private String words[];
public Sentence(String[] words) { this.words = words; }
@Override
public String toString() {
return "Sentence{" +
"words=" + Arrays.toString(words) +
[Code] ....
Is it possible to shorten the sort function to just this?
public String sorted() {
return Arrays.sort(words);
}
I want to write an application that inputs a sentence, tokenizes the words with method split and reverse the words (not the letters)...I am stuck at the last part: how to reverse them...should I use the method reverse(); ?
Here is my code..
import java.util.Scanner;
import java.util.StringTokenizer;
public class ReversedWords {
//execute application
public static void main( String [] args) {
//get sentence
[code]....