Practice›Java Fundamentals›Module 11. Modern Java›11.3 Records

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11.3 Records — adding your own methods

Lesson

Запись — всё ещё класс

An empty body is the common case, but a record can hold methods like any class. What it cannot hold is mutable state: the components are fixed, so methods only compute from them.

Worked example

record Student(String name, int score) {
    String label() {
        return name + " (" + score + ")";
    }

    boolean passed() {
        return score >= 60;
    }
}

Inside the record the components are used by their plain names — name, score — without this. and without brackets.

Records fit naturally with streams: a list of records filtered and mapped reads almost like a sentence, which is what the next lessons build on.

▶ Try it: run this, then change something and run it again.

record Student(String name, int score) {

    String label() {
        return name + " (" + score + ")";
    }

    boolean passed() {
        return score >= 60;
    }
}

public class Main {
    public static void main(String[] args) {
        Student a = new Student("Ada", 90);
        Student b = new Student("Sam", 55);
        System.out.println(a.label());
        System.out.println(a.passed());
        System.out.println(b.passed());
    }
}

Inside a record, a component is used as...

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What can a record method NOT do?

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Type exactly what this program prints.

record Item(String name, int price) {

    int withTax() {
        return price * 2;
    }
}

public class Main { public static void main(String[] a){
    Item i = new Item("pen", 5);
    System.out.println(i.withTax());
    System.out.println(i.name());
}}

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A record with methods is useful when...

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True or false?

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