Data hiding in Java - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a private variable in a class.

Java

class Person {
    [1] String name;
}

Drag options to blanks, or click blank then click option'

Apublic

Bprivate

Cprotected

Dstatic

Attempts:

3 left

💡 Hint

Common Mistakes

Using public instead of private, which does not hide the data.

Using static which is unrelated to access control.

The keyword private hides the variable from outside the class, enabling data hiding.

2fill in blank

medium

Complete the code to provide a public method to access the private variable.

Java

class Person {
    private String name;
    public String [1]() {
        return name;
    }
}

Drag options to blanks, or click blank then click option'

AgetName

Bname

CsetName

DprintName

Attempts:

3 left

💡 Hint

Common Mistakes

Using setName which is a setter, not a getter.

Using the variable name directly as method name.

The method to access a private variable is called a getter, usually named starting with 'get'.

3fill in blank

hard

Fix the error in the setter method to correctly set the private variable.

Java

class Person {
    private String name;
    public void setName(String [1]) {
        name = [1];
    }
}

Drag options to blanks, or click blank then click option'

Athis.name

Bname

CnewName

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same name for parameter and field without 'this' keyword.

Not assigning the parameter value to the field.

The parameter name should be different from the field name to avoid confusion. Using newName allows setting name = newName;.

4fill in blank

hard

Fill both blanks to correctly implement a setter method using 'this' keyword.

Java

class Person {
    private int age;
    public void setAge([1] age) {
        [2].age = age;
    }
}

Drag options to blanks, or click blank then click option'

Aint

Bthis

CPerson

Dprivate

Attempts:

3 left

💡 Hint

Common Mistakes

Using class name instead of 'this' to refer to the field.

Omitting the parameter type.

The setter method takes an int parameter and uses this to refer to the current object's field.

5fill in blank

hard

Fill all three blanks to create a class with a private variable and a getter.

Java

class Car {
    private String [1];
    public String [2]() {
        return [3];
    }
}

Drag options to blanks, or click blank then click option'

Amodel

BgetModel

DsetModel

Attempts:

3 left

💡 Hint

Common Mistakes

Using setter name instead of getter.

Returning a wrong variable name.

The private variable is model. The getter method is getModel and it returns the variable model.