Public Mutable Field (ARCH4186)

Key java.quality.public-mutable-field · Severity warning · Category quality

Public mutable fields break encapsulation; any caller can mutate the value with no checks. Make the field private and guard it with accessors.

Incorrect

public class Account {
    public double balance;
}

Correct

public class Account {
    private double balance;

    public double getBalance() { return balance; }

    public void deposit(double amount) {
        if (amount <= 0) throw new IllegalArgumentException();
        balance += amount;
    }
}

Fix

Make the field private and govern changes through validating accessor/mutator methods.