Introduction to public in Java
Public is a keyword in Java which is used for functions as well as variables in a program. Whenever we use the keyword public in front of variables then the variables are available in methods in which it has not been declared as well. Also when we declare a method in Java as well we can use the function in classes where it has not been declared as well. Public is an access modifier in Java. There are also other access modifiers in Java like private, protected and default. Private keyword in Java is such that once a function is declared as private then the respective function cannot be accessed in other classes where it has not been defined. An access modifier is basically a restriction of methods, functions and classes in a program which cannot be accessed in other classes or methods.
Syntax:
The syntax of public is shown below. In the below example, the variable word is declared as public inside the class Example. The variable word is available in the functions. The functions are Sum() and average(). So, the variable word is readily available in other functions although it has not been specifically called in the respective function. In case of a variable which has been declared as private cannot be accessed in other functions or classes. Therefore, in case where the variable is not allowed to get accessed in other functions, the access modifier private is used.
Code:
Class Example
{
Public int hello;
Public void sum(int a)
{
}
Public void average(int a)
{
}
}
Examples of public in Java
Given below are the examples mentioned:
Example #1
Now we see a coding example in which the public access modifier is used and then it is used to add two numbers. There are two classes. One is the main() in which we create an object of Addition() and then we call the other class through two numbers. The name of the object created is obj and it is very useful in calculating the sum. There can also be other functions and classes such as Multiply as well as Divide. The coding example is a simple program where there are two classes.
Code:
class Addition {
public int add(int a, int b){
return a+b;
}
}
public class Main{
public static void main(String args[]){
Addition obj = new Addition();
System.out.println(obj.add(50, 50));
}
}
Output:
The two numbers which are included are 50 both. When we add the two numbers, we get the final output as 100 as shown. The function used to add the two numbers are add() and there is an object that is created. We can also create other classes where we can have other functionalities and we can create that object in the main() of the program.
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Example #2
In this coding example, we create an object in the main(). The below program is used to multiply two numbers and produce the multiplication output. There is a single object obj which is created and is used to call two numbers. One is the number which has double as its type which is used in the same class. In the Hello class, there is a main() which is created and is used to call the square() as well as the number which has its type as double.
Code:
class XYZ{
public double num = 100;
public int square(int a){
return a*a;
}
}
public class Hello{
public static void main(String args[]){
XYZ obj = new XYZ();
System.out.println(obj.num);
System.out.println(obj.square(10));
}
}
Output:
The sample output is a clear depiction of the two variables which are called inside the main(). First, the number 100 which has double as its type is shown as well as the square of a number which is there in a function. There is a function square() which shows the square of a number and is created inside another class and then inside another class there is a main() which calls the Square() and the number is shown as input. The number which is shown as input in this case is 10 and the square of the respective number is 100 which is shown in the output panel.
Advantages of public in Java
- Unlike the private access modifier which is the most restricted modifier, public is used when functions are used to call in classes.
- It is available in classes, package, subclass(within the same package) and subclass(within other packages).
- Also, the functions are also available in other classes.
- Public functionality is used for running programs which has a single main() and there are multiple other functions which has different functionality which are called inside the main().
Conclusion
In this article, we see a number of coding examples as well as the various advantages of Public Access Modifier in Java. We also see the other access modifiers such as private, protected and default. The disadvantages of private are also there which has enormous restriction. The accessibility of other access modifiers are also shown in this article in a diagram
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