The access levels in a program can be introduced by the concept of Access Modifiers. Access Modifier in a java program is used to specify the scope of a field, method, constructor, or even a class. We can hence change the access level of fields, constructors, methods, and class by applying the access modifier to it. There are 4 types of access modifiers namely as follows:
| Access Modifier | Description |
|---|---|
| Public | The access level of a public modifier is everywhere. It can be accessed from within the class, outside the class, within the package, and even outside the package. |
| Private | The access level of a private modifier is only within the class, the modifier is mentioned in. It cannot be accessed from outside that class. |
| Protected | The access level of a protected modifier is within the package (it is mentioned in) and outside the package through child class. If you do not make the child class, it cannot be accessed from outside the package. |
| Default | The access level of a default modifier is only within the package. It cannot be accessed from outside the package. If you do not specify any access level, it will be set to default. |
Implementation: Access Modifier usages
Example 1: Using one single class to show the scope of Access modifiers
Java
// java Program to illustrate One Single Class for Scope of// Access modifiers // Importing input output classesimport java.io.*; // Main classclass GFG { // Method 1 public static void method1() { // Print statement for method with public type System.out.println( "This method uses Public access modifier"); } // Method 2 private static void method2() { // Print statement for method with private type System.out.println( "This method uses Private access modifier"); } // Method 3 protected static void method3() { // Print statement for method with protected type System.out.println( "This method uses Protected access modifier"); } // Method 4 static void method4() { // Print statement for static default type method System.out.println( "This method uses Default access modifier"); } // Method 5 // Main driver method public static void main(String[] args) { // Display message only System.out.println( "Various access modifiers being used in the same class"); // Calling all the above methods in main() method // body method1(); method2(); method3(); method4(); }} |
Various access modifiers being used in the same class This method uses Public access modifier This method uses Private access modifier This method uses Protected access modifier This method uses Default access modifier
Example 2: Using two different classes in the same package to show the scope of Access modifiers
Java
// Java Program to illustrate Use of Two Different Classes// in the Same Package to Show the Scope of Access modifiers // Importing input output classesimport java.io.*; // Main class// Helper classclass Helper { // Method 1 public static void method1() { // Print statement whenever this method is called System.out.println( "This method uses Public access modifier"); } // Method 2 // Would not be accessed if set to "private" public static void method2() { // Print statement whenever this method is called System.out.println( "This method uses Private access modifier"); } // Method 3 protected static void method3() { // Print statement whenever this method is called System.out.println( "This method uses Protected access modifier"); } // Method 4 static void method4() { // Print statement whenever this method is called System.out.println( "This method uses Default access modifier"); }} // Class 2// Main classclass GFG { // Main driver method public static void main(String[] args) { // Display message only System.out.println( "Various access modifiers being used in the same class"); // Calling all the above methods in main() method // body Helper.method1(); Helper.method2(); Helper.method3(); Helper.method4(); }} |
Various access modifiers being used in the same class This method uses Public access modifier This method uses Private access modifier This method uses Protected access modifier This method uses Default access modifier
Note:
In method 2 if we set access modifier to “private” we get error as:
prog.java:25: error: method2() has private access in SecondClass
SecondClass.method2();// calling method2
(Reason: private members cannot be accessed outside the class)
Let us discuss the above missing scenario where we are accessing private members of a class we can use getter and setter methods to fetch and set the value of various parameters in Java.
Example 3: Access Private data members of a class
Java
// Java Program to access Private Members of a Class// using Getter and Setter methods // Class 1// Helper class for AccessModifierclass Helper { // Member variables of this class // private fields private int age; private String name; // Method 1 // Setter method used to set age, a private field public void setAge(int age) { this.age = age; } // Method 2 // Setter method used to set name, a private field public void setName(String name) { this.name = name; } // Method 3 // Getter method used to get age, a private field. public int getAge() { return this.age; } // Method 4 // Getter method used to get name, a private field public String getName() { return this.name; }} // Class 2// Main classpublic class GFG { // Main driver method public static void main(String[] args) { Helper ob = new Helper(); // Set value of private fields ob.setAge(888); // Set value of private fields ob.setName("Geeksfor Geeks "); // Print and display the age using // get value of private fields System.out.println("Age: " + ob.getAge()); // Print and display the name using // get value of private fields System.out.println("Name: " + ob.getName()); }} |
Age: 888 Name: Geeksfor Geeks
Conclusion: So there are 4 access modifiers to specify the scope of methods, fields, classes or constructors, illustrated by Java program examples.
