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).
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.
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 .
This 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);
Im writing a simple program to understand classes and objects. Basically what I have is a file called Program.java where I have my main method.I have another file called Person.java which I want to use to create Person objects. That person can have a name, email adress, phone number, etc.I put both these files in the same folder.in Program.java my first statement is:
My problem is that when I compile Program.java i get an error message saying that the package Person.java does not exist.So my question is, when you create a class that you want to use for objects, how do you import that class into your class with the main method so that you can use instances of your other class?
- 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.)
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(){
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};
I was wondering if I could write this code in one line.
import java.util.Scanner; public class Test { public static void main(String[] args) { Scanner sc = new Scanner(System.in); char ch = sc.next().charAt(0); } }
Can I combine "import java.util.Scanner","Scanner sc = new Scanner(System.in);" and "char ch = sc.next().charAt(0);" in one statement? The object created from the class Scanner may be anonymous but it doesn't concern me!
How to create object for "class B" and call the "function_B" from other different class D where class D has no connection with class A? Here is my program.
public class A(){ void print(){} } class B{ void function_B(){} } class C{ void function_C(){} }
Here, A, B, C are in the same package. But class D is in different package.
I will give an example below of what I am talking about. in C++ I know I would need a copy constructor because I would be pointing blindly in the heap if I deleted a object in the struct.
We have a Class/struct animal and three animals in that class/struct, a dog, a cat and a cow. Each animal has a baby and then I will give the animal a name in main. But if I delete one of the dogs puppies because I sold him wouldn't I being pointing off in the heap and have a leak?
Also since Java doesn't have structs can I put a class inside a class?
I am working on some enhancement on application. I have a requirement. The flow is as below
In a jsp file one selection dropdown exists and a body. Selection dropdown is written as custom tag library and is included in jsp file eg tag.tld whose code exists in tag.java code for other parts of jsp are written in that *.jsp file itself. eg test.jsp
i.e test.jsp calls tag.tld to include selection dropdown
I now want a hashmap created in tag.java to be available in jsp file and I want to use it in one of the javascript function available in same jsp file for validation
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?
What this interface inside that abstract class does. Looking for some examples to how can i use it ....
public abstract class Expression { public abstract String toString(); public abstract SimpleExpression evaluate(); public void show() { System.out.println(this + " = " + evaluate());
I saw an example where an (inner)class is declared inside the main method, this is correct or not and why/when it's reasonable to use?so smth like this
public class myClass() { public static void myMethod(myInnerClass obj) { if (obj.method())
