Getters, Setters

10.2.1 Why Use Getters and Setters?

Because fields are private for safety, you still need a controlled way to read and write their values from outside.

This is where getters and setters come in:

• A getter lets you read a field’s value.

• A setter lets you change a field’s value — but only with your validation rules.

Together, they act like gatekeepers.
They give you full control over:

• What is visible,

• What is changeable,

• And how.

10.2.2 Example of Getters and Setters

Let’s see a simple Person class that uses getters and setters.

java
public class Person {
    private String name;
    private int age;

    public String getName() {
        return name; // getter
    }

    public void setName(String name) {
        this.name = name; // setter
    }

    public int getAge() {
        return age; // getter
    }

    public void setAge(int age) {
        if (age > 0) { // validation
            this.age = age;
        }
    }
}

Key points:

• Fields are private.

• getName() and getAge() return the current values.

• setName() and setAge() update values — setAge() checks for valid input.

This pattern keeps the class’s internal data safe and prevents illegal values.

10.2.3 Mini Lab: Putting It Together

Below is a mini program that shows how to use getters and setters in practice.

java
public class Person {
    private String name;
    private int age;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name; 
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        if (age > 0) {
            this.age = age;
        }
    }

    public static void main(String[] args) {
        Person p = new Person();
        p.setName("Alice");
        p.setAge(25);

        System.out.println("Name: " + p.getName());
        System.out.println("Age: " + p.getAge());
    }
}

When you run it:

• The Person object p has private fields.

• You set them safely through setters.

• You read them safely through getters.

• Direct modification is impossible from outside.