I've tried to write a package and two classes this way:
<path>/pack/Aclass.java
Java Code: package pack;
public class Aclass<T> {
private T t;
public void set(T t) {
this.t = t;
[code]....
My working directory is e:ajava. in package p1 i create two classes c1 and c2. net beans creates three files e:ajavap1srcp1, e:ajavap1srcc1, e:ajavap1srcc2. package runs without a hitch. i create another package p2 under e:ajava. i want to use class c1 in p2. pray what on earth should be my import statement in the p2 source code after the first statement 'package p2'. another related querry what should i include in my class path so as to gain access to c1 and c2 in source code of p2.
View Replies View RelatedFacing problem with java.net.InetAddress class while validating special form of IPv6 address.
Please check the following piece of code.
String ipv6 = "0:0:0:0:0:ffff:a1f:e403";
try{
final Inet6Address i6 = (Inet6Address) InetAddress.getByName(ipv6);
System.out.println(i6);
}
catch(ClassCastException e){
System.out.println("Not a proper ip: "+e);
}
It is throwing ClassCastException.
Let's say hypothetically you're making a huge program and use a lot of imports (ex import java.util). If you only need a few specific things from java.util, will it use more memory importing java.util.* compared to only importing lets say java.util.Scanner, java.util.ArrayList, etc. Basically does importing a whole package use more (if any at all) memory than only importing specific package parts?
View Replies View Relatedmy new class had me download eclipse and for some reason it won't let me type anything until I create a document. creating a document creates a package and that lets me create a class which then it will let me start typing code...so wtf is wrong with eclipse and why is it bulling me into having this "package" line in my code when I never had anything like that in other ide's?
View Replies View RelatedI have a folder of classes that I am packaging together. Some classes are being packaged and compiling just fine. My other classes in the same package, however, are saying that they cannot find these classes.
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 new to java i dont understand the difference between the abstract and inheritance i mean we use the abstract class with extends with other class name ,even we do that same in the inheritance pls tell me main difference between abstract and inheritance...
View Replies View Relatedhow inheritence and exception work together ?? what are the rules ??
View Replies View RelatedThough have been playing around with my ebook but finding it difficult to get along with the topic PACKAGE&INTERFACES, I find it challenging to write a package file despite the book I currently studying and online tutorial.. so I want a more explanatory format to comprehend the piece cos without knowing it.
View Replies View RelatedI am trying to make a jar file in intelliJ. My directory that holds all the java classes is C:rafficProjectsrccege. In cege there is a package ui where there is a class GuiMain. And I have imported the GuiMain() in my Main() class.
I have this code lines:
package cege;
import cege.ui.GuiMain;
and when I use the terminal in the intelliJ and write the command:
C: rafficProjectsrccege>javac *.java
I get this message:
Main.java:3: error: package cege.ui does not exist
import cege.ui.GuiMain;
but actually, I have already put this line in my code. what could be the problem?
I'm having problems with this I've code like:
Java Code:
Public Class{
Objects
Constructor(){}
ActionListener Method(){}
Main Function()}
[Code]....
but I cannot declare variables in this method, how can I do this what can be the simplest method?
In addition: I've a marksheet class, a calculator class, & in main class I've 2 buttons one for marksheet & one for calculator, how can I make it so that if user clicks on marksheet button that class should be called & so?
If I define a class which contains a few static fields, and then have a few classes who inherit this class, then all these classes would have the static field as well. Now my question is the following: would all those sub classes (and the base class itself) share the same object, or would each class have one object for all it's instances?
View Replies View RelatedThis code doesn't recognise the package ( and therefore class ) timetest3, when I try to import it. The package I try to reference/call, follows, and works fine.
import javax.swing.JOptionPane;
import timetest3.TimeTest3;
public class timetest4 {
public static void main(String args[]) {
TimeTest3 time = new TimeTest3();
time.setTime(13,45,52);
[Code] ......
I am in an intro programming class and we got assigned a problem for creating a super class with about a dozen sub classes for generating a random word(via WordGetter class) and then comparing that word to a variety of different patterns(like: does the word contain "re"). We were given the super class which looks like this...
public class Pattern {
public boolean matches(String text) {
return true;
}
public String toString() {
return "(TRUE)";
[code]...
and from this class, we have to write subclasses that override those three methods. I am struggling to understand inheritance and I am not really sure where to even start. Here is the instructions for the first sub class we need to write...
"CONTAINS" SUBCLASS
Constructor: The constructor accepts a String named ‘letters’.
Matches: This pattern matches any text that contains at least one occurrence of each ‘letter’.
toString: produces the text “(CONTAINS <LETTERS>)” where <LETTERS> is the ‘letters’ string.
getLetters(): this method must return letters.
equals(Object): careful on this one. Two Contains are equal if they have the same letters (order is not relevant).
(Example):
Pattern p = new Contains(“re”);
boolean f1 = p.matches(“renew”); // f1 is true
boolean f2 = p.matches(“zoo”); // f2 is false
String s = p.toString(); // s is “(CONTAINS re)”
boolean f3 = p.equals(new Contains(“er”)); // f3 is true.. really..
The first is clear , new Person().printPerson(); displays Person but for the second : new Student().printPerson(); it accesses the Student constructor that points to the Person class => object. It builds the Person instance then goes back to the Student constuctor .Both methods are private and to my knowledge invisible one to the other , except that you cant run the the Person one because it's private so the only one in the Student class is the Student one . Guess it 's incorrect , but why ? (is because private methods cant be overriden and somehow the super class one always has priority ? , even if it's private?)
public class Test {
public static void main(String[] args) {
new Person().printPerson();
new Student().printPerson();
[code]....
If i have 2 classes, Top and ClassB which extends Top
public class Top {
String variable;
public Top(){
setVariable();
}
void setVariable(){
variable = "variable is initialized in Main Class";
[code]....
So what is happening when ClassB inherits from Top?I know that the B constructor is calling super, so does that mean its calling setVariable (in Top?) but as its overridden in ClassB, then that is whats being called and setting the String variable?
Here is my abstract Boat class.
public abstract class Boat{
private int height;
private int length;
private int width;
private double boatValue;
private double chargeRate;
private Owner owner;
public Owner getOwner() {
return owner;
[Code] ....
i was leaning inheritance and tried to implement it in Java.This is my base class vehicl.java
public class vehicle{
private int topSpeed;
private int cubicCap;
private String modelName;
private boolean hasAlloy;
[code]...
I also have a derived class called car.java.What i wanted to do in the derived class was that i wanted to override the constructor as well as the getInfo() method from the base class.I wanted to add an additional attribute to the car "numberSeats" and display tat too when the object to car class calls the getInfo() method .It showed an error "identifier required" when i tried to compile car.java program.
import java.util.Scanner;
public class car extends vehicle{
//int numberSeats;
//System.out.println("Enter the number of Seats");
Scanner numberSeats=new Scanner(System.in);
numberSeats=numberSeats.nextInt();
//System.out.println(numberSeats.nextInt());
[code]....
explain the errors that i get when i tried to compile car.java without using super keyword or without defining the constructor from the Car class ?
I am trying to understand the package and import functions.
The path to access the file " library.book" is
C:UsersKameshDesktopJava SessionJAVAOCA7ooklibrary
and i can see 3 txt files
Book.class
Book.ctxt
Book.java
while compiling i am getting <identifier>expected error.
Here is the code :
package library;
public class Book {
public String isbn;
public void printBook() {}
}
package building;
[Code] .....
The error i get is <identifier>expected.
i have a program in UNIX directory /home/me/java/src
package bin;
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello World");
}
}
I have manage to compile it successfully(class file will be in bin directory) using command below: javac -d /home/t_bmf/java/bin HelloWorld.java
My problem now is how would I execute the class in bin directory in UNIX? I already tried different ways on how to execute it as suggested in my internet research The one I tried is this:
java $CLASSPATH:.:bin/HelloWorld
but I got this error message:
Exception in thread "main" java.lang.NoClassDefFoundError: :/:bin/HelloWorld
Caused by: java.lang.ClassNotFoundException: :.:bin.HelloWorld
[code]....
Source packages
1.First package : CarDealer.java (JFrame form)
2. Second package : Vehicle.java (JFrame form)
- The user runs CarDealer JFrame in which appears a JTexField in which he types in some characters (pretending he types some data about selling licence).
- The user clicks on the JButton "Save" that stores the characters typed in inside a String variable called strLicence.
- The user clicks on the JButton "Open 'Vehicle Form'" that opens the Vehicle JFrame.
- Finally, in the Vehicle JFrame I want to write a code that can see/use the value of the String variable called strLicence.
In other words, for example, I want to store the value of strLicence in a new variable declared in the Vehicle class.
(Actually I'm working with a long and elaborate project for the dissertation of my bachelor's degree, so, for cutting to the chase, I simplified it by creating an essential JFrame project.)
I used netbeans
1. CarDealer.java
package Firstpackage;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.JFrame;
[code]....
I also attach the netbeans project in a zip file ....
Design Patterns are one form of reuse. so is inheritance. what are the similarities and difference between them?
View Replies View RelatedI am writing small pieces of code to make sure I understand Java basics and I have the following.
package teams1;
public abstract class Team1{
private String sport = new String();
public abstract String getSport();
public abstract void setSport();
}
import teams1.*;
[Code] .....
It doesn't compile because sport is private in the super class, but I thought FootballTeam1 would inherit it's own copy of sport because it is extending Team1.
I have created an application that I wish for people to be able to run from command line, like so:
java myApp [filename]
Problem is my application uses functions from 3 .Jar files.
Here is how my folder(Assume it is called MyApplication) currently looks:
Application(folder)(contains .class files + source code)
jar1.jar
jar2.jar
jar3.jar
Manifest.txt
I understand I need add some information to the Manifest.txt file but I am struggling in adding stuff to it in the correct format.
Assuming the above folder is called my MyApplication, what I need to put in the Manifest and how to build it all as a Jar File.
how access levels work from subclasses and other packages, and I have discovered that a class cannot see it's own protected variable from another package which I thought it would be. I know that it says in the java docs "The protected modifier specifies that the member can only be accessed within its own package (as with package-private) and, in addition, by a subclass of its class in another package." but I thought that would also include it's own class.
Java Code:
package food;
import food.fruit.*;
public class Food {
protected int protecte = 5;
private int privat = 5;
protected void method(){
[Code] ....