package SandBox2;

public class Test {
    public static void main(String[] args) {
        System.out.println(new A.Builder<>().foo(1).build());
        System.out.println(new B.Builder<>().foo(1).bar("abc").build());
        System.out.println(new C.Builder<>().foo(1).bar("abc").baz(0.5).build());
    }
}

class A {
    public final int foo;

    public A(int foo) {
        this.foo = foo;
    }

    @Override
    public String toString() {
        return "A{" + "foo=" + foo + '}';
    }

    public static class Builder <T extends Builder<T>> {
        public int foo;

        public T foo(int foo) {
            this.foo = foo;
            return (T)this;
        }

        public A build() {
            return new A(foo);
        }
    }
}

class B extends A {
    public final String bar;

    public B(int foo, String bar) {
        super(foo);
        this.bar = bar;
    }

    @Override
    public String toString() {
        return "B{" + "foo=" + foo + ", bar='" + bar + '\'' + '}';
    }

    public static class Builder <T extends B.Builder<T>> extends A.Builder<T> {
        protected String bar;

        public T bar(String bar) {
            this.bar = bar;
            return (T)this;
        }

        public B build() {
            return new B(foo, bar);
        }
    }
}

class C extends B {
    public final double baz;

    public C(int foo, String bar, double baz) {
        super(foo, bar);
        this.baz = baz;
    }

    @Override
    public String toString() {
        return "C{" + "foo=" + foo + ", bar='" + bar + '\'' + ", baz=" + baz + '}';
    }

    public static class Builder <T extends C.Builder<T>> extends B.Builder<T> {
        protected double baz;

        public T baz(double baz) {
            this.baz = baz;
            return (T)this;
        }

        public C build() {
            return new C(foo, bar, baz);
        }
    }
}