Java Access Modifiers Tutorial

Java access modifiers help to control or restrict the accessibility of the members of a class. In day to day programming, we need to use access modifiers for a class, constructors, fields, and methods.

The below table summarizes all the java access modifiers and their visibility to other classes.

Access Modifier	Class	Package	Subclasses	Everywhere
private	✔	✘	✘	✘
default	✔	✔	✘	✘
protected	✔	✔	✔	✘
public	✔	✔	✔	✔

Details about Java access modifiers

private access modifier

Java private access modifiers restrict accessing the members of the class from outside the class. All private members in the class can be accessed within the same class only.
```
    public class Bird {
        private String name;                //private fields
        private String color;

        private Bird(String name) {         //private constructor
            this.name = name;
        }

        private String getBirdName() {      //private method
            return name;
        }

        public Bird(String name, String color) {
            this(name);

            this.color = color;
        }
    }
```
- private fields/ private class variables
  
  Java fields with private access modifiers restrict access from outside the class. In other words, private fields are accessible within the same class only.
```
    private String name;    //private field
```
- private constructor
  
  Java constructor with private access modifiers restrict access from outside the class. In other words, a private constructor cannot use to create objects outside the class. However, we can call private constructors from other constructors or other methods which also in the same class.
```
    private Bird(String name) {         //private constructor
        this.name = name;
    }
```
```
    this(name);         //calling private constructor
```
```
    Bird bird = new Bird("Parrot");         //creating objects inside the same class
```
  Note: A famous example of the usage of a private constructor is a singleton design pattern.
- private methods
  
  Java methods with private access modifiers restrict access from outside the class. The private methods cannot access from the outside the class but within the same class only.
```
    private String getBirdName() {      //private method
        return name;
    }
```

default access modifier

A Java class member with default access modifiers only accessible within the same class and the same package. When we write code we dont write any keywords to to declare the member as a default member.

    class Bird {                    //default class

        String name;                //default fields
        String color;

        Bird(String name) {         //default constructor
            this.name = name;
        }

        String getBirdName() {      //default method
            return name;
        }

        public Bird(String name, String color) {
            this(name);

            this.color = color;
        }
    }

default class

Java class with default access modifiers can only accessible within the same class or same package. The class will not visible to the other classes which are in different packages.
```
    class Bird {                    //default class
```

default fields/ default class variables

Java fields with default access modifiers can only accessible within the same class or same package.
```
    String name;    //default field
```

default constructor

Java constructor with default access modifiers can only accessible within the same class or same package.

    Bird(String name) {         //default constructor
        this.name = name;
    }

    this(name);         //calling default constructor

    Bird bird = new Bird("Parrot");         //creating objects inside the same package

default methods

Java methods with default access modifiers can only accessible within the same class or same package.
```
    String getBirdName() {      //default method
        return name;
    }
```

protected access modifier

A Java class member with protected access modifiers can be accessible by all subclasses even though they are from outside of the package. Apart from that, members who are in the same class and the same package also can access the protected members.
```
    public class Bird {

        protected String name;                //protected fields
        protected String color;

        protected Bird(String name) {         //protected constructor
            this.name = name;
        }

        protected String getBirdName() {      //protected method
            return name;
        }

        public Bird(String name, String color) {
            this(name);

            this.color = color;
        }
    }
```
- protected fields/ protected class variables
  
  Java fields with protected access modifiers can only accessible by the members which are in the same class, the same package and all the subclasses.
```
    protected String name;    //protected field
```
- protected constructor
  
  Java constructor with protected access modifiers can only accessible by the members which are in the same class, the same package and all the subclasses.
```
    protected Bird(String name) {         //protected constructor
        this.name = name;
    }
```
```
    this(name);         //calling protected constructor
```
```
    Bird bird = new Bird("Parrot");         //creating objects within all subclass
```
- protected methods
  
  Java methods with protected access modifiers can only accessible by the members which are in the same class, the same package and all the subclasses.
```
    protected String getBirdName() {      //protected method
        return name;
    }
```

public access modifier

A Java class member with public access modifiers can be accessible from the everywhere.

    public class Bird {                    //public class

        public String name;                //public fields
        public String color;

        public Bird(String name) {         //public constructor
            this.name = name;
        }

        public String getBirdName() {      //public method
            return name;
        }

        public public Bird(String name, String color) {
            this(name);

            this.color = color;
        }
    }

public class

Java class with public access modifiers is visible to everywhere.
```
    public class Bird {    //public class
```

public fields/ public class variables

Java fields with default access modifiers can be accessible from the everywhere.
```
    public String name;    //public field
```

public constructor

Java constructor with default access modifiers can be accessible from the everywhere.

    public Bird(String name) {         //public constructor
        this.name = name;
    }

    this(name);         //calling public constructor

    Bird bird = new Bird("Parrot");         //creating objects everywhere

public methods

Java methods with default access modifiers can be accessible from the everywhere.
```
    public String getBirdName() {      //public method
        return name;
    }
```

Summary of where to apply access modifiers

Access Modifier	Class	Constructor	Method	Field
private	✘	✔	✔	✔
default	✔	✔	✔	✔
protected	✘	✔	✔	✔
public	✔	✔	✔	✔

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Java Access Modifiers Tutorial

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Details about Java access modifiers

private access modifier

private fields/ private class variables

private constructor

private methods

default access modifier

default class

default fields/ default class variables

default constructor

default methods

protected access modifier

protected fields/ protected class variables

protected constructor

protected methods

public access modifier

public class

public fields/ public class variables

public constructor

public methods

Summary of where to apply access modifiers

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