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What are differences between user defined packages and predefined packages in java?
As we know, default package of java.lang.*; is implicitly called if it is not explicitly called Ok, So. Package is Collection Classes ( abstract or interfaces).
Package Creation :-
1 ) First line of the program, in which you want create a package must be a your desired package name starting with package keyword and followed by semicolon.
2 ) While creating package, it is not necessary to write public before each class name.
3 ) But, each and ever method must be public.
Creating or Compiling Package :-
Syntax :-
D:\Practice\Javac -d < Path of program >
Complete Example :-
package TYBCS;
class Mathematics
{
public int addNumbers(int num1,int num2)
{
return(num1+num2);
}
public static double addFloatNum(double num1,double num2,double num3)
{
return(num1+num2+num3);
}
}
class Maximum
{
public int getMaxOutofThree(int n1,int n2,int n3)
{
int num=0;
if(n1>n2 && n1>n3) { num=n1; }
if(n2>n1 && n2>n3) { num=n2; }
if(n3>n1 && n3>n2) { num=n3; }
return num;
}
}
class Practice
{
public static void main(String args[])
{
Mathematics m=new Mathematics();
Maximum mx=new Maximum();
System.out.println("Addition 5+5 : "+m.addNumbers(5,5));
System.out.println("Addition f 2.5+2.5 : "+m.addFloatNum(2.5,2.5,2.5));
System.out.println("Max Number 7, 8 , 1 : "+mx.getMaxOutofThree(7,8,1));
}
}
/*
Output:-
D:\Data>javac -d D:\Data\ Practice.java
D:\Data>java TYBCS.Practice
Addition 5+5 : 10
Addition 2.5+2.5 : 7.5
Max Number 7, 8 , 1 : 8
D:\Data>
*/
Predefinedpackages and classes are those that come installed as part of the standard Java library; it is expected that each conforming Java implementation will have these libraries available to them without having to package those classes as part of the project. User defined packages, in contrast, are those classes not defined by the Java interface and must be packaged as part of an application (e.g. placed in the JAR file) in order to provide the implementation class files needed to have the program run.
Predefined packages
Java provides various predefined classes and interfaces (API’s) organized under packages. These are known as predefined packages, following is the list of predefined packages in java −
java.lang − This package provides the language basics.
java.util − This packages provides classes and interfaces (API’s) related to collection frame work, events, data structure and other utility classes such as date.
java.io − This packages provides classes and interfaces for file operations, and other input and output operations.
USER Defined pakages
To create a package, we choose a package name and to include the classes, interfaces, enumerations, etc, inside the package, we write the package with its name at the top of every source file.
There can be only one package statement in each type of file. If we do not write class, interfaces, inside any package, then they will be placed in the current default package.
Predefined packages are a part of the Java API and are accessible to all. One can create their own packages and distribute them.
Rashmi
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What are the different types of package in java?
1.user defined packages 2.predefined packages
What is the difference between predifined data structure and user define data structure?
A predefined structure or, more generally, a predefined type, is a type that is defined internally by the compiler implementation. For instance Microsoft's implementation includes predefined runtime information and GUID structures, amongst other predefined types such as size_t. These types are built in to the compiler itself, so you won't find them in a header file. By contrast, user-defined structures (types) are those you define yourself, or are provided for you by a third party.
What are predefined codes?
Predefined codes or the predefined functions are the codes small or large codes which are predefined by the maker of the language. In C++ the predefined codes can be included in the program by the header files. These codes are placed in files and functions could be used to access them. Like a simple console Code to output "Hello World" uses a predefined code cout
Can a class extend exception?
Yes You can. The features of such a class would be similar to what an Exception would have but not exactly as a predefined Java Exception. When you create a user defined exception you extend the java.lang.Exception class which in turn extends the java.lang.Throwable so indirectly you are extending the Throwable class while creating a user defined exception...
Name the following-A key word to use the classes defined in a package?
To access the classes which are present in other packages, we have to import the package to our program using the keyword 'import'. Eg: import packagename.subpackage.Class; OR import packagename.subpackage.*; /*Adds all the class which are present in package*/ 'extends' is the keyword used to inherit the classes defined in other packages.
What are the different types of package in java?
1.user defined packages 2.predefined packages
What is the difference between pre defined functions and user defined functions?
Predefined functions are functions that have been written and we can use them in our C++ statements. But we must know how to use each of these predefined functions.
What does predefined mean?
Already defined, previously defined.
In c programming is main predefined or user defined?
main is predeclared and user defined.
What is the difference between predefined functions and user defined functions?
Predefined functions are built-in functions provided by a programming language or software application for common tasks, such as mathematical calculations or string manipulation. User-defined functions are functions created by the programmer to perform specific tasks tailored to the program's requirements. Predefined functions are readily available and can be used without additional coding, while user-defined functions require the programmer to define the function's behavior and implementation.
What is the difference between predifined data structure and user define data structure?
A predefined structure or, more generally, a predefined type, is a type that is defined internally by the compiler implementation. For instance Microsoft's implementation includes predefined runtime information and GUID structures, amongst other predefined types such as size_t. These types are built in to the compiler itself, so you won't find them in a header file. By contrast, user-defined structures (types) are those you define yourself, or are provided for you by a third party.
Does the word predefined have a hyphen pre-defined?
Yes, always. -Kierra Pace
What does the word predefined mean?
"Predefined" refers to something that has been determined, established, or specified in advance. It often refers to settings, values, or options that are already established before they are used or implemented.
Is word macro is predefined?
Macros are not pre-defined. You can create them yourself at any time.
What is defined as the gap between the home market and a foreign market resulting from the perception and understanding of cultural and business differences?
defined as the gap between the home market and a foreign market resulting from the perception and understanding of cultural and business differences.
What is the term used to describe the predefined settings that are used when an application is first installed?
Software-defined
List out the predefined classes in PHP?
Classes are not like predefined functions-there are quite a lot of functions, a class is similar to creating your own function - on a very basic level please do not swamp me with lists of the differences between a class and a function I already know! - anyway, anything predefined within php will be available to view in the PHP manual - downloadable from the php website and is part of the php package. but to save you a bit of time here are a list of pre-defined classes (or rather resevered words that are classes): http://php.net/manual/en/reserved.classes.php
