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Usage Examples

The record-wither library makes it simple to create modified copies of immutable Java records.

Below are practical examples derived directly from the test suite:

import io.github.mrtimeey.records.Withable;

public enum Status {
    ACTIVE,
    INACTIVE
}

public record TestRecord(String name, String description, int count, boolean active, double score, Status status)
        implements Withable<TestRecord> {}

Example: Updating an int field​

TestRecord base = new TestRecord("Test", "RecordWither", 3, true, 1.5, Status.ACTIVE);

TestRecord updated = base.with(TestRecord::count, 42);

// base remains unchanged
System.out.println(base.count()); // 3

// updated contains the new value
System.out.println(updated.count()); // 42

Example: Updating a String field​

TestRecord updated = base.with(TestRecord::name, "Neu");

System.out.println(base.name());   // Test
System.out.println(updated.name()); // Neu

Example: Updating another String field​

TestRecord updated = base.with(TestRecord::description, "NeuDesc");

System.out.println(base.description());   // RecordWither
System.out.println(updated.description()); // NeuDesc

Example: Updating a boolean field​

TestRecord updated = base.with(TestRecord::active, false);

System.out.println(base.active());   // true
System.out.println(updated.active()); // false

Example: Updating a double field​

TestRecord updated = base.with(TestRecord::score, 9.99);

System.out.println(base.score());   // 1.5
System.out.println(updated.score()); // 9.99

Example: Updating an enum field​

TestRecord updated = base.with(TestRecord::status, Status.INACTIVE);

System.out.println(base.status());   // ACTIVE
System.out.println(updated.status()); // INACTIVE