Law of Demeter

Reports Law of Demeter violations.

The Law of Demeter is not really a law, but specifies a style guideline: never call a method on an object received from another call. The code that follows this guideline is easier to maintain, adapt, and refactor, has less coupling between methods, less duplication, and better information hiding. On the other hand, you may need to write many wrapper methods to meet this guideline.

Example:

  boolean pay(Customer c, Invoice invoice) {
    int dollars = c.getWallet().contents; // violation
    if (dollars >= invoice.getAmount()) {
      Wallet w = c.getWallet();
      w.subtract(invoice.getAmount()); // violation
      return true;
    }
    return false;
  }

The above example might be better implemented as a method payInvoice(Invoice invoice) in Customer.

Locating this inspection

By ID

Can be used to locate inspection in e.g. Qodana configuration files, where you can quickly enable or disable it, or adjust its settings.

LawOfDemeter

Via Settings dialog

Path to the inspection settings via IntelliJ Platform IDE Settings dialog, when you need to adjust inspection settings directly from your IDE.

Settings or Preferences | Editor | Inspections | Java | Data flow

Use the Ignore calls to library methods and access to library fields option to ignore Law of Demeter violations that can't be fixed without changing a library.

Inspection options

Here you can find the description of settings available for the Law of Demeter inspection, and the reference of their default values.

Ignore calls to library methods and access to library fields: Default: Selected

Availability

By default bundled with: IntelliJ IDEA 2024.1, Qodana for JVM 2024.1,
Can be installed with plugin: Java, 241.18072

Last modified: 18 June 2024