The access to classes, constructors, methods, and fields are regulated using access modifiers i.e. a class can control what information or data can be accessible by other classes.

Java provides a number of access modifiers to help you set the level of access you want for classes as well as the fields, methods and constructors in your classes. A member has a package or default accessibility when no accessibility modifier is specified.

Access Modifiers

•  private
•  protected
•  public

public access modifier

public means every classes or every subclass or superclass can access fields.The public access modifier is accessible everywhere. It has the widest scope among all other modifiers.

private access modifier

The private access modifier is accessible only within class.

protected access modifier

The protected access modifier is accessible within package and outside the package but through inheritance only.The protected access modifier can be applied on the data member, method and constructor. It can't be applied on the class.

class BaseClass {
 
      publicintx = 10;
      privateinty = 10;
      protectedintz = 10;
      inta = 10; // Implicit Default Access Modifier
 
      publicint getX() {
            returnx;
      }
 
      publicvoid setX(int x) {
            this.x = x;
      }
 
      privateintgetY() {
            returny;
      }
 
      privatevoidsetY(int y) {
            this.y = y;
      }
 
      protectedint getZ() {
            returnz;
      }
 
      protectedvoid setZ(int z) {
            this.z = z;
      }
 
      int getA() {
            returna;
      }
 
      void setA(int a) {
            this.a = a;
      }
}
 
publicclass Sample extends BaseClass {
 
      publicstaticvoid main(String args[]) {
            BaseClass rr = new BaseClass();
            rr.z = 0;
            Sample subClassObj = new Sample();
            // Access Modifiers - Public
            System.out.println("Value of x is : " + subClassObj.x);
            subClassObj.setX(20);
            System.out.println("Value of x is : " + subClassObj.x);
            // Access Modifiers - Public
            // If we remove the comments it would result in a compilaton
            // error as the fields and methods being accessed are private
 
            // Access Modifiers - Protected
            System.out.println("Value of z is : " + subClassObj.z);
            subClassObj.setZ(30);
            System.out.println("Value of z is : " + subClassObj.z);
            // Access Modifiers - Default
            System.out.println("Value of x is : " + subClassObj.a);
            subClassObj.setA(20);
            System.out.println("Value of x is : " + subClassObj.a);
      }
}

Output-:

Value of x is : 10

Value of x is : 20

Value of z is : 10

Value of z is : 30

Value of x is : 10

Value of x is : 20

Access Modifier | within class | within package | subclass only | outside                                                                                                                                            package

Private                             Y                       N                            N                  N

Default                            Y                       Y                             N                  N

Protected                       Y                      Y                              Y                  N

Public                             Y                       Y                               Y                  Y