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Getters and Setters Should Access the Expected Fields

Medium
maintainabilityencapsulation

What is it?​

This practice ensures that getters and setters properly access and modify the fields they are intended to encapsulate within a class.

Why apply it?​

Getters and setters are crucial for encapsulating data and maintaining a clear contract with class users. Incorrectly accessing the wrong fields disrupts this contract and can cause unexpected behavior in applications.

How to fix it?​

Always verify that your getters return and your setters modify the correct fields that correspond to the method name.

Examples​

Example 1:​

Negative​

In this noncompliant example, the Person class incorrectly accesses the wrong fields in its getters and setters.

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

    public String getName() {  /* Noncompliant: returns incorrect field */
        return String.valueOf(this.age);
    }

    public void setName(String name) {  /* Noncompliant: updates incorrect field */
        this.age = Integer.parseInt(name);
    }

    public int getAge() {  /* Noncompliant: returns incorrect field */
        return this.name.length();
    }

    public void setAge(int age) {  /* Noncompliant: updates incorrect field */
        this.name = String.valueOf(age);
    }
}

Example 2:​

Positive​

In this compliant example, the Person class correctly uses getters and setters to access and modify its private fields.

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

    public String getName() {  /* Compliant */
        return this.name;
    }

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

    public int getAge() {  /* Compliant */
        return this.age;
    }

    public void setAge(int age) {  /* Compliant */
        this.age = age;
    }
}

Negative​

In this noncompliant example, the Rectangle class incorrectly links the setters to the wrong fields.

public class Rectangle {
    private double width;
    private double height;

    public double getWidth() {  /* Noncompliant: returns incorrect field */
        return this.height;
    }

    public void setWidth(double width) {  /* Noncompliant: updates incorrect field */
        this.height = width;
    }

    public double getHeight() {  /* Noncompliant: returns incorrect field */
        return this.width;
    }

    public void setHeight(double height) {  /* Noncompliant: updates incorrect field */
        this.width = height;
    }
}

Example 3:​

Positive​

This compliant example ensures the Rectangle class manages its fields accurately with corresponding getters and setters.

public class Rectangle {
    private double width;
    private double height;

    public double getWidth() {  /* Compliant */
        return this.width;
    }

    public void setWidth(double width) {  /* Compliant */
        this.width = width;
    }

    public double getHeight() {  /* Compliant */
        return this.height;
    }

    public void setHeight(double height) {  /* Compliant */
        this.height = height;
    }
}