I am a beginner at Java programming. how to implement my own String class, but I have to provide my own implementation for the following methods:
public MyString1(char[ ] chars)
public char charAt(int index)
public int length( )
ublic MyString1 substring(int begin, int end)
public MyString1 toLowerCase( )
[code]....
I have looked through the API, but I don't really understand where to start.
I have some spatial datasets which are availabe in a opensource metadata catalog software GeoNetwork and in a PostGIS database.The problem is that the student who created the database used different IDs for the same datasets. So the IDs in the GeoNetwork differs from the IDs in the postGIS database. They only have the same name So, if someone uploads a new dataset into GeoNetwork, the same dataset is uploaded into a postGis database too.
Now I want to add a ID column into the database to give the field the same ID like the ID in geonetwork. I think I can only do this with using the filename cause they are same in both cases.Now I want to alter the table in eclipse with following code:
PHP Code:
Connection con = null;
Statement stmt = null;
String query = null;
String filen = filename.substring(0, filename.indexOf('.'));
con = DriverManager.getConnection("jdbc:postgresql_postGIS://localhost:5433" + "user=postgres;password=dominik1;" + "database=geonetwork"); --> (the connection data will later be in a properties file)
query = "ALTER TABLE " + filen + " ADD GN_id INTEGER(10) ";
stmt = con.createStatement();
stmt.execute(query); mh_sh_highlight_all('php');
But i get the following findbug error:
Failed to execute goal org.codehaus.mojo:findbugs-maven-plugin:2.5.2:check (default) on project services: failed with 1 bug
org.fao.geonet.services.resources.UploadAndProcess .exec(Element, ServiceContext) passes a nonconstant String to an execute method on an SQL statement ["org.fao.geonet.services.resources.UploadAndProces s"] At UploadAndProcess.java:[lines 83-299]..
I tried to suppress this error and worked with PreparedStatement and String.Format but I can't get rid of this error.
I would like to implement a variable in a class that is used in another class, how can I do that?
I have a Mall class and a Customer class I would like to associate the position of the customer that is in the Mall class and also implement the same in the Customer class.
Here is a small part of the code without all the methods.
//the two objects
Mall m = new Mall("RandomMall",50,30);
Customer c1= new Customer("Jack",1240);
//the first part of the mall class without the methods
class Mall{
private String name;
private int width,length;
String[][]grid = new String[width][length];
[code]...
I'm writing a simple queue program using a netbeans as a GUI program I've used netbeans GUI editor to create the GUI my main problem was I've written the queuing code to a button function it works but it runs only once and the queue becomes empty on the second run. So I implemented a class which will create the queue outside the button click event but when I do that I get a Symbol not found: method error . The place where I get the error:
addStd1.setText("Add Student");
addStd1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
addStd1ActionPerformed(evt);
}
My button function with the class:
class stdQueCls{
Queue stdQue;
public stdQueCls(){
stdQue = new LinkedList();
}
private void addStd1ActionPerformed(java.awt.event.ActionEvent evt) {
[code]....
i'm getting cryptic error messages for the following code:
class MyChar implements CharSequence{
private String s;
public MyChar(String input)
{
StringBuilder b = new StringBuilder(input);
b.reverse();
this.s = b.toString();
[code]....
it's telling me something's wrong with the class modifier and that my class can't implement chart
While learning how to implement the class DynamicArrayStack, I've run into some operators and syntax I'm unfamiliar with!
public class DynamicArrayStack{
protected int capacity
public static int MINCAPACITY=1<<15;
protected int[] stackRep;
protected int top = -1;
//initializes stack to use an array of default length
public DynamicArrayStack()
this(CAPACITY)
[code]....
how to 'implement' an interface and 'extend' a class. Now I want to try and recall the information by memory without using any reference material.
Implementing an interface...
Java Code: //This interface will hold information for cell phones//Like saying... you can't BE a cell phone unless you have this information, at the very least
public interface CellInfo {
public void model();
public void make();
public void androidVer();
}
//Now I implement the interface for a class called Galaxy, which is a class about a specific phone
public class Galaxy implements CellInfo
public void model() {
System.out.println("I'm a Galaxy S5.");
}
public void make() {
System.out.println("I'm made by Samsung.");
[code]....
this program used to implement palindrome String of using stack and queue.i wont to enter string by scanner how can i chang it ??????
class Palindrom_homwork1{
int top=-1;
int rear=-1;
int front=-1;
int max=3;
int max1=3;
char array[]=new char[max];
char array1[]=new char[max1];
[code]....
This assignment uses the following description to implement a Dialog class for the Leap Year Problem. We need to decompose this problem into 2 classes:
1.The Date.java class: is a public class that represents a date composed of a month , day, and a year. So you need to declare month, day, and year as integers. Date has 1 constructor and 4 methods. Write the constructor for Date which has 3 parameters: int m, int d, int y ; (As an example of a constructor with 2 parameters for example chapter 3 page 152 code listing 3-13 has a perfect example for you to use which is the BankAccount.java.) and the 4 methods:
"dayIs()" which returns a day. It has no parameter.
"monthIs()" which returns a month. It has no parameter.
"yearIs()" which returns a year. It has not parameter.
"isLeapYear()" which returns a boolean value.
"isLeapYear()" has one parameter year and returns a boolean. Write the method isLeapYear() knowing that a year is defined to be a leapyear it is a multiple of 4, and if it is is a multiple of 100, it must also be a multiple of 400. isLeapYear() thus decides when a year is a leap year. (see the discussion on "Hints for Assign5" to discover specific examples of a LeapYear).
The purpose of the Date.java is to decide whether a year is a leap year. Here is a definition of when a year is considered a leap year :
-year y1 is a leap year if it is multiple of 4.
-year y1 is a leap year if it is a multiple of 100, it must be a multiple of 400.
-Otherwise y1 is not a leap year.
2. The DateJDialog.java class: implements the GUI. Please use the Dialog boxes developed in the book in chapter2 in pages 99-100 in the code-listing 2-32 (NamesDialog.java) for input and output.
Remember that you will prompt the user to enter:
-a month;
-a day;
-a year
And out of these 3 you will be able to create a Date. Then you will use the dialog box to tell the user whether the year entered was a leapyear or not a leapyear.
Remember that we defined in 1- what it means a year is a leap year or not a leap year.
Do not forget to compile the 2 java files. To verify that the DateJDialog.java works, in TextPad after you compile DateJDialog.java, Click on Tools, Click on "Run Java Application".
When you have completed the assignment, please remember to submit Date.java and DateJDialog.java.
So I created an interface which has the method
int getCalls();
I am trying to implement this method in another class but I'm not sure how to do so. My attempt is:
public getCalls(){ return getCalls(); }
When I run the program it sends the following exception:
Exception in thread "main" java.lang.StackOverflowError
at FibonacciForget.getCalls(FibonacciForget.java:14)
and it highlights the [return getCalls();] part.
What is the correct way to implement the getCalls() method?
I am working on a problem that computes primes. Here is the problem: You are going to implement a class that computes all the primes up to some integer n. The technique you are to use was developed by a Greek named Eratosthenes who lived in the third century BC. The technique is known as the Sieve of Eratosthenes. The algorithm is described by the following pseudocode:
create a queue and fill it with the consecutive integers 2 through n inclusive.
create an empty queue to store primes.
do {
obtain the next prime p by removing the first value in the queue of numbers.
put p into the queue of primes.
go through the queue of numbers, eliminating numbers divisible by p.
} while (p < sqrt(n))
all remaining values in numbers queue are prime, so transfer them to primes queue
You are to use the Queue interface provided. When you want to construct a Queue object, you should make it of type LinkedQueue. These classes are included. You should define a class called Sieve with the following public methods:
Sieve() - Constructs a sieve object.
void computeTo(int n) - This is the method that should implement the sieve algorithm. All prime computations must be implemented using this algorithm. The method should compute all primes up to and including n. It should throw an IllegalArgumentException if n is less than 2.
void reportResults() - This method should report the primes to System.out. It should throw an IllegalStateException if no legal call has been made yet on the computeTo method. It is okay for it to have an extra space at the end of each line.
int getMax() - This is a convenience method that will let the client find out the value of n that was used the last time computeTo was called. It should throw an IllegalStateException if no legal call has been made yet on the computeTo method.
int getCount() - This method should return the number of primes that were found on the last call on computeTo. It should throw an IllegalStateException if no legal call has been made yet on the computeTo method.
Your reportResults method should print the maximum n used and should then show a list of the primes, 12 per line with a space after each prime. Notice that there is no guarantee that the number of primes will be a multiple of 12. The calls on reportResults must exactly reproduce the format of the sample log. The final line of output that appears in the log reporting the percentage of primes is generated by the main program, not by the call on reportResults.
Here is my class Sieve. I am having difficulty getting all the primes into the proper queue:
public class Sieve {
private Queue<Integer> primes;
private Queue<Integer> numList;
private boolean computed = false;
private int max;
private int count = 0;
[Code] ....
When I input say, 20, I only get 2, 3, and 11 back as primes. Somewhere in the algorithm (lines 40-54) I seem to have gone awry, but I'm not certain where. Here are the other classes:
SieveMain:
// This program computes all the prime numbers up to a given integer n. It uses the classic "Sieve of Eratosthenes" to do so.
import java.util.*;
public class SieveMain {
public static void main(String[] args) {
System.out.println("This program computes all prime numbers up to a");
System.out.println("maximum using the Sieve of Eratosthenes.");
System.out.println();
[Code] .....
Below is the requirements and code. I am getting the error CODELAB ANALYSIS: LOGICAL ERROR(S)We think you might want to consider using: >
Hints:
-Correct solutions that use equals almost certainly also uses high
-Correct solutions that use equals almost certainly also uses low
Assume the existence of a Widget class that implements the Comparable interface and thus has a compareTo method that accepts an Object parameter and returns an int . Write an efficient static method , getWidgetMatch, that has two parameters . The first parameter is a reference to a Widget object . The second parameter is a potentially very large array of Widget objects that has been sorted in ascending order based on the Widget compareTo method . The getWidgetMatch searches for an element in the array that matches the first parameter on the basis of the equals method and returns true if found and false otherwise.
public static boolean getWidgetMatch(Widget a, Widget[] b){
int bot=0;
int top=b.length-1;
int x = 0;
int y=0;
while (bot >= top)
[code]....
how it is decided which class will implement a session listener interface? Which class will implement HttpSessionListener? Which one will implement HttpSessionActivationListener, HttpSessionBindingListener or HttpSessionAttributeListener?
View Replies View RelatedHow do you enforce any class which implements an interface should also implement comparable too? Say for instance you may have an interface
public interface Task
{ ... }
public class DoThis implements Task { ... }
public class DoThis1 implements Task { ... }
I want all of the classes which implements the interface Task to implement comparable too. Of course I can just say implements Task, Comparable. But is there something which we could do from interface level, i mean interface Task level?
I have been researching the Iterator and making a class implement iterable. I have seen this example shown below and was wondering how I could change this so that iterable() is not called upon in the main. I would like to be able to make a method that returns an instance of a class that implements the Iterator interface hopefully an inner class. This is because my program will not have a main and will be supplied with a main that includes a new Object with will use the iterator method.
import java.util.*;
public class IteratorDemo {
public static void main(String args[]) {
// Create an array list
ArrayList al = new ArrayList();
// add elements to the array list
al.add("C");
[Code] ....
This is all I have been able to understand from what I want to do. This does not work and this is what I am trying to achieve
public class MyArrayList implements Iterable {
public static final int DEFAULT_SIZE = 5;
public static final int EXPANSION = 5;
private int capacity;
private int size;
private Object[] items;
[Code] ...
I am trying to implement the following example to override the equality and hashCode method if the class has reference type member. I do get the expected result "true" for equal and "false" for non-equal objects. But the print statement in the Circle's equal method is not executed when the objects values are not equal. I don't know what i am missing, though i get the equality result "false" as expected for non equal objects.
class Point{
private int x, y;
Point (int x, int y) {
this.x =x;
this.y = y;
[code]....
Okay, I am supposed to implement the functionalities of the Set class using a private data member of type ListReferencedBased<E>,how the ListReferenceBased works with what I am trying to accomplish.I am trying to complete Set.java, and I have barely started and much of the code doesn't work. ListReferenceBased was given to me completed.
import java.util.Iterator;
pubic class ListReferenceBased<E> implements ListInterface<E>, Iterable<E>{
/** reference to the first element of the list */
private Node<E> head;
/** number of items in list */
private int numItems;
[code]....
This code is directly from Swing: I'm using Eclipse and keep getting an error on line 10 saying :
"The type JTextField must implement the inherited abstract method ActionListener.actionPerformed(ActionEvent)."
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
[Code] ......
i am trying to write a class method which will take in a string and returns a string which is the reversed version of that string. it compiles fine but when i try to run it it states Main method not found in class StringReverse,please define the main method as public static void main(String[]args). I am new to java and cannot figure out
import javax.swing.JOptionPane;
public class StringReverse {
public String reverseString(String str){
JOptionPane.showInputDialog(null,"Please enter word");
char c = str.charAt(str.length()-1);
if(str.length() == 1) return Character.toString(c);
return c + reverseString(str.substring(0,str.length()-1));}}
I want to write an app that declares a class Person(String name, int age), and an Account class, Account(int code, double balance).But, additionally, every Person has at most 3 accounts, and each account has a Peron associated with it.
my code so far...
public class Person {
private String name;
private int age;
private Account[] accounts;
private int numOfAccounts;
public Person(String name,int age){
this.name=name;
[code]....
My problem is:When I make data input for a person, and additionally I want to read data for the account(s) that this rerson has, what code should I write to create a new Account object as account[numOfAccounts].And, what is the code to assign an owner to a new created Account object?
There exists a relationship between the two classes, but I cannot find the way to implement this relation....
I would like to understand why only String class is immutable.
1. Why String class is immutable? What is the main reason for making String class as immutable.
2. Why there is no int pool or float pool or Integer pool etc, why only String pool.
this is my code :
String name = "Mohan";
String is a immutable class and where these character stored when we assign some character. How the logics are working inside the String class.
why my sub class object just gives me a blank when it comes to the String. It works just fine for the super class but when I get to the sub class the program just gives me a blank. I won't let me input anything for the String. On line 24 of the client I attempt to input a new String but it doesn't ever let me enter one so then any call to getName is just a blank.
I have altered my super and sub class as well as the client to try to get it to work. I tried a local variable in the client, I tried using protected in the super class, I tried a handful of other things.
import java.util.*;
public class TryingItOutClient {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
[code]....
What does the line Console[] conList mean? How am I going to access the string values in class consolelist?
class ConsoleInfo
{
private String conTitle;
private double conPrice;
private int conQty;
private String conPic;
[Code] .....
I have a little a problem with String object in this class ....
public class Personne {
private String nom;
private String prenom;
private int age;
public Personne(){
this(null, null, 0);
[Code] ....
When i call the class personne with the Personne() i get these errors in compiling-time :
Exception in thread "main" java.lang.NullPointerException
at java.lang.String.<init>(Unknown Source)
at Personne.setNom(Personne.java:18)
at Personne.<init>(Personne.java:12)
at Personne.<init>(Personne.java:8)
at Main.main(Main.java:4) // The line wich i inisialize my object in my main method.
I defined a java class thus:
class Info{
public String name;
public String version;
public String arch;
double CPUSpeed;
double ranUtil, CPUUtil;
};
But each object of such a class takes many bytes. How can I limit it to one fourth of a Kilo-Byte?