Java Access Modifiers: Controlling Your Code's Visibility

Java is an object-oriented programming language that provides various access modifiers to control the visibility of classes, interfaces, methods, and instance variables. Access modifiers specify the level of access that a class or its members have from other parts of the program.

Definitions

Public

Public members are accessible from anywhere in the program. It has the highest level of visibility. For example, a public method in a class can be called from any other class.

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public class MyClass {
    public void myPublicMethod() {
        // method code
    }
}

Private

Private members are accessible only within the same class. It has the lowest level of visibility. For example, a private method in a class can only be called from that class.

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public class MyClass {
    private int myPrivateVariable;
    private void myPrivateMethod() {
        // method code
    }
}

Protected

Protected members are accessible within the same class, subclasses, and the same package. For example, a protected method in a class can be called from that class, any subclass of that class, and any class within the same package.

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public class MyClass {
    protected void myProtectedMethod() {
        // method code
    }
}

Default (No Keyword)

Default members are accessible within the same package only. It is also known as package-private. For example, a default method in a class can be called from any class within the same package.

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class MyClass {
    void myDefaultMethod() {
        // method code
    }
}

Best Practices

It is important to use access modifiers appropriately to ensure proper encapsulation and security in your code. Here are some best practices for using access modifiers:

• Encapsulate data by making instance variables private and providing public methods to access and modify them. This helps to prevent unwanted access and modification of data from other parts of the program.

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public class MyClass {
    private int myPrivateVariable;
    
    public void setMyPrivateVariable(int value) {
        this.myPrivateVariable = value;
    }
    
    public int getMyPrivateVariable() {
        return this.myPrivateVariable;
    }
}

• Use the final keyword with public or protected access modifiers to create constants. This helps to ensure that the value of the variable is not modified elsewhere in the program.

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public class MyClass {
    public static final int MY_CONSTANT = 100;
}

• Avoid overuse of public access modifier for security reasons. Public members can be accessed from anywhere in the program, which can be a security risk. Use the appropriate access modifier based on the level of visibility required.

Final Thoughts

In summary, access modifiers in Java provide a way to control the visibility of classes, interfaces, methods, and instance variables. Proper use of access modifiers can help ensure proper encapsulation, security, and maintainability in your code. For further reading, you can refer to the Java documentation.