Class Cannot See Its Own Protected Variable From Another Package
Jan 30, 2014
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] ....
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Nov 12, 2014
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 ....
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Nov 1, 2005
I don't know why class Object have two PROTECTED method -- clone() and finalize(). And in JUnit's source code, I notice that kent write :public class AClass extends Object {}I really don't understand what diffrient frompublic class AClass {}
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May 19, 2014
I am trying to declare fields as protected String custom.field.1096; in my java class but it does not allow me. Can I not declare the field as above? Is there any workaround to achieve this?
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Apr 19, 2014
New York City temperature ranges for 12 months are given below:
Jan Feb Mar Apr May JunJul Aug Sep Oct Nov Dec
25-38 26-40 34-4843-58 52-68 62-7768-83 60-75 49-65 41-54 31-4347-61
1.Create an int array of size 366 to save the daily temperatures for a leap year.
2.Fill the array with randomly generated numbers between the ranges for that month. For example, for the first 31 days of the year (that is the month of January) randomly generate numbers between 25 and 38. For the next 29 days (the Month of February) randomly generate numbers between 26 and 40, and so on for every month.
The formula for generating random numbers between two numbers m and n is, (int)Math.floor(m + Math.random() * (n-m+1)); Or you may choose to use the Random Class from the util package.
3.Print the average temperature for each month.
4.Print the hottest day for the entire year, in the following format: Example: The hottest day was Thursday, July 4. Also, mention what the temperature Was on this day. You may assume that January 1 was a Monday.
5.Print the coldest day for the entire year, in the following format: Example: The coldest day was Tuesday, February 12. Also, mention what the temperature was on this day. Again, assume that January 1 was a Monday.
6.How many days in the year was it below 330 F and how many more than 750F.
So far i Have this
import java.util.Random;
public class NYCTemp
{
String [] days = {"Sunday","Monday","Tuesday","Wednesday","Thursday ","Friday","Saturday"};
String [] months = {"January","February","March","April","May","June" ,"July","August","September","October","November", "December"};
int [] daysInMonth = {31,29,31,30,31,31,30,31,30,31,30,31};
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Apr 30, 2014
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.
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Feb 17, 2014
I am puzzled by a note in the book I am reading (by Mala Gupta). Page 55 says "All java components you've heard of can be defined within a java class: import and package statements, variables.....". But the online oracle doc (tutorial) clearly says the following 2 statments:
"If present, package statement must be the very first line in a file"
"To import a specific member into the current file, put an import statement at the beginning of the file before any type definitions but after the package statement, if there is one. " (Here).
So, how can import and package be present inside a class ? (This seems to go against the 2 statements from oracle online tutorial).
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Mar 7, 2015
I'm trying to access class file which is inside the package and package is inside the jar file but I can't access that class file inside my source file . All files are on desktop .
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Jan 8, 2014
I've 3 classes.
1. Circle
2. GetInputFromUser
3. testCircle
package ABC;
public class Circle {
private double radius;
public double getRadius() {
return radius;
[Code] .....
In the testCircle class, in the line: getRadius = ui1.GetInput();
It's showing the error: The method GetInput(float) in the type GetInputFromUser is not applicable for the arguments ()
And when I do: getRadius = ui1.GetInput(rad);
It's showing the error: rad cannot be resolved
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May 22, 2014
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?
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May 31, 2014
I have a program with 4 classes, all of them in the same package, one of them is the Main class, and in that class I declared a variable named "port" of type int. One of the 3 another ones is the class Connection class, which it requires the port variable. I want to use this variable in the Connection class. How can I do it?Both classes are shown below:
Main.java
package server;
/* Imports */
/* Another variables */
int port; /* <-- IS THIS ONE */
[code]....
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Dec 8, 2014
I have a class Tree in which all the methods to build a tree are in place. But however I would want variable of by Tree which is pointing to the last node being added to the tree.
So basically every time you keep adding a node to the tree you tail pointer gets updated to point to the last node. I have this so far.
public class NonEmptyTree implements Tree {
private Tree left;
private int data;
private int leftleafCount;
private int rightleafCount;
private Tree right;
private Tree tail; // This variable must be shared by all the object. There needs to just one tail pointer to the tree.
public Tree insert( data ) {
tail = // gets updated every time when new node gets added.
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Mar 12, 2015
I am developing a program that seems to need to transfer the value of a variable from one class to another. However, neither of the classes is the main class.
This simplified code should make my problem clear:
This is my main class where I create runone from Class1 and runtwo from Class2:
public class MainClass {
public static void main(String[] args) {
Class1 runone = new Class1();
Class2 runtwo = new Class2();
}
}
This is Class1 where I set up x and give it the value 20. I also have a getter-method to be able to access the value of x from other classes.
public class Class1 {
int x = 20;
public int getX(){
return x;
}}
This is Class2, where I try to access the value of x that was set up in runone.
public class Class2 {
int y;
public Class2() {
y = runone.getX + 10;
System.out.println(y);
}
}
Unfortunately, I get the error message "runone cannot be resolved to a variable."
What do I do to be able to access the variable x (that is set up in Class1) from Class2?
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Apr 13, 2015
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]...
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Aug 16, 2014
It just wont work... Everytime I try to pass a variable into a class it sets it to 0. What to do.
The variable should be '2', but it prints out as 0!?
Java Code: package Zoo;
import java.util.Random;
public class Animal {
Random random = new Random();
public void Eat(){
System.out.println("The animal starts to eat.");
[Code]...
The method bash, needs the variable 'playerTwo' to be 2, to carry on. But it prints out 0.
Int the animal constructor, I passed in the variable from another class, and it prints out 2 in the constructor like it should. But outside of the constructor it is equal to 0.
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Jan 5, 2014
As the title says, how can I pass a value from one variable to another class?
Example:
So here I'm switching one frame to another, called "redigeraProjekt". Now in this class, I want the value from .getSelectedIndex() pass over to that class. I've tried to use the variable "valIListan" but it cannot find it. Probably because it's "private" (?)
valIListan = listaAllaSpelProjekt.getSelectedIndex();
redigeraProjekt npj = new redigeraProjekt(); // "switching" to another frame
npj.setVisible(true);
this.setVisible(false);
I hope you understand what I'm saying
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Sep 22, 2014
I'm working on a project that contains multiple classes. Each class contains and must contain only PRIVATE variables. Here's my issue. When my test code calls for a new instance of "StudentClass" as so:
StudentClass studentClass = new StudentClass(offeredClass.getClassIdNumber(),
offeredClass.getClassName(),
offeredClass.getClassroom());
The corresponding constructor won't let me initialize it's variables because they are declared private within another class, as shown here:
StudentClass (float classIdNumber, String className, Classroom room){
this.classIdNumber = classIdNumber;
this.className = className;
this.room = room;
}
When getClassName, getClassroom, and getClassIdNumber are passed to a toString() method elsewhere in my test code. the output is returned just fine. When passed through the StudentClass, I'm getting Null across the board.
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Mar 28, 2015
I am new in java. Is there any difference between protected or default when we are talking about one package?
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Mar 9, 2014
I was just wondering.. my understanding from everywhere I have read is interface cannot be private or protected (not at the top level) but when we declare an interface without any modifier it is default.
We know default modifier has more restricted access than protected.. public > protected > default > private
Now since an interface can be public and default then why not protected as clearly if they were allowed to be protected they could be implemented by a subclass..?
While typing this question I figured how would an interface know which is it's subclass? that is why Java allows only public i.e. any class can implement it or default i.e. any class within the package can implement.. am I right?
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Apr 14, 2015
Sandwich class. I have thus far completed creating a sandwich class with a seperate sandwich Tester class to run with it. (this is according to the assignment). Now I must create Static variables for the sandwich class:
Add two static variables to the Sandwich class to count how many sandwiches are sold and how many slices of tomato are used. Initialize each to 0.Where do you add code to increment the sandwich counter? Determine this and then add code.
public class Sandwich
{
static int numOfSold = 0;
static int slicesUsed = 0;
private String meat;
private int numOfSlicesOfTomato;
private boolean lettuce;
[code]....
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Jul 24, 2014
why I cant access a variable from another class, in particular why in the main class cant i assign " quiz1 = getQuizOne();" ? It constantly giving me error.
Java Code:
import java.util.Scanner;
public class Grade {
private int quiz1, quiz2, midtermExam, finalExam = 0;
public static void main(String[] args)
{
Student John = new Student();
John.StudentData();
[code]....
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Oct 9, 2014
I would like to pass a variable I have in my main to my JFrame. In my main I calculate which pictures I should show in my JFrame. Is it possible to make objects of these pictures in my main class and use them in my JFrame? something like my code below.
public class JFrameTesting {
public static void main(String[] args) {
Image ImageVariable = Toolkit.getDefaultToolkit().getImage("C:1.jpg");
MyJFrame f = new MyJFrame();
f.setTitle("Drawing Graphics in Frames");
[code]....
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Mar 19, 2014
Let's say I have a Junit4 class FooTest.java and variable token. At some point in class the token gets instantiated.
Java Code:
public class Foo {
private String token;
@Before
public void setUp() {
// serious is steps to get the application to a certain state where token can get extracted
....
token = extractToken();
}
} mh_sh_highlight_all('java');
Now I have another class User.java where I need to use this token. Can I inject this token somehow into that class? There is no relation between Foo and User. I can't use Provider method in the configure file because extraction of the token depends on certain system's state and can't be called anywhere anytime.
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Mar 25, 2014
I'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?
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Feb 1, 2015
Why is it that a protected method cannot be accessed polymorphically outside its package. I suspect the reason is that some compile-time checks have to be performed. Is this correct?
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May 2, 2015
I have a class named Base and a private variable named _hopcount i have 10 instances of class base i use _hopcount as creteria to some if but other instances edit _hopcount so i want to prevent _hopcount edit by other instances; I want to have private variable which other instances of same class can't modify it.
public class Base extends TypedAtomicActor {
private int _hopcount = 0;
if(_hopcount <= 3) {
some code;
}
public function() {
_hopCount += 1;
}
}
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