Programmer: Lifelong Learning: 2019

AutoValue runs inside javac as a standard annotation processor.
Use Builder when there too many parameters or same type.

@AutoValue
public abstract class Foo {
  public static Foo create(String text, int number) {
    // defensive copies, preconditions
    return new AutoValue_Foo(text, number);
  }
  public abstract String text(); // or getText(), if you like
  public abstract int number();
}

Set a default value for a property

static Builder builder() {
  return new AutoValue_Foo.Builder()
      .setSomeIntegerField(1).setSomeImmutableSetFeild(ImmutableSet.of());
}

@Nullable properties

@Nullable abstract Foo foo();

toBuilder

public abstract Builder toBuilder();

AutoValue.Builder

@AutoValue
public abstract class Foo {
  static Builder builder() {
    return new AutoValue_Foo.Builder();
  }

  public abstract String text(); // or getText(), if you like
  public abstract int number();

  @AutoValue.Builder
  abstract static class Builder {
    abstract Builder text(String value);
    abstract Builder number(int value);
    abstract Foo build();
  }  
}

Optional properties

public abstract Optional<String> optionalProperty();


@AutoValue.Builder
public abstract static class Builder {
  public abstract Builder SetOptionalProperty(String optionalProperty);
}

autoBuild

@AutoValue.Builder
public abstract static class Builder {
  abstract Animal autoBuild(); 

  public Animal build() {
    // we can do validation, or normalization, or any other logic here.
    return autoBuild();
  }
}

Misc

Use immutable properties.
We can perform validations at create factory or build method.
We can write our own equals or hashcode methods.

Set a default value for a property

@Nullable properties

toBuilder

AutoValue.Builder

Optional properties

autoBuild

Misc

Resource

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