TinyRefactorings.java

// CHALLENGE (work in pairs):
// Improve code snippets listed below –
//


// 1 - implement Xml class instead of XmlMarshaller
class XmlMarshaller {
    byte[] marshallToXml(Invoice invoice) {
        ByteArrayOutputStream outStream = new ByteArrayOutputStream();
        JaxbMarshaller jaxbMarshaller = new JaxbMarshaller(Invoice.class);
        jaxbMarshaller.marshallObject(invoice, outStream);
        byte[] resultXml = outStream.toByteArray();
        IOUtils.closeQuietly(outStream);
        return resultXml;
    }
}
byte[] t = new XmlMarchaller().marshallToXml(invoce);
//----
class Xml {
    ByteArrayOutputStream os = new ByteArrayOutputStream();
    Xml(Invoice invoice) {
        new JaxbMarshaller(Invoice.class).marchallObject(invoice, this.os);
    }
    byte[] toByteArray() {
        return this.os.toByteArray();
    }
}
byte[] t = new Xml(invoice).toByteArray();


// 2 - refactor to eliminate all null checks and branching
class AmazonS3File {

    private final String path;
    private Optional<Metadata> metadata;

    void attach(Metadata metadata) {
        this.metadata = Optional.of(metadata);
    }

    //@Nullable
    Optional<Metadata> getMetadata() {
        return metadata;
    }
}

class AmazonS3Bucket {
    void upload(AmazonS3File file) {
        //… upload ...
        file
            .flatMap(File::getMetadata)
            .map(it -> uploadMetadata(it));
        //if (file.getMetadata() != null) {
        //    uploadMetadata(file.getMetadata());
        //}
    }

    private void uploadMetadata(Metadata metadata) {
        ....
    }
}



// 4 - fix conflicting method names. No getters & setters allowed!
user.ban() // returns user's ban and the corresponding information (if any)
user.ban() // bans a user

//----

user.banDetails() // returns user's ban and the corresponding information (if any)
user.ban() // bans a user
// user.activeBan() // word-play
// user.putABan()

// 5 – get rid of procedural design
interface MoneyFormatter {
  String format(Money money);
}

//----

class Money {
  String asString();
}

// ---

class ISO111MFOrmattedMoney implements FormattedMoney { ... }
interface FormattedMoney {
    FormattedMoney(Money money) {
    }
    string toString() {
    }
}
//
class PrettyMoney {
    PrettyMoney(Money money) {
    }
    string toString() {
    }
}

// 6 - implement "fullName" method, so that it returned "firstName lastName" if nickname is missing
// or "firstName <nickname> lastName" if nickname is present.
// for example – "Robert Martin" or "Robert <Uncle Bob> Martin"
// don't optimize prematurely (e.g. prefer simple String concatenation over StringBuilder).
class User {
    private final Optional<String> nickName;
    private final String firstName;
    private final String lastName;

    String fullName() {
        return nickname
                .map(it -> firstName + " <" + it + "> " + lastName)
                .orElseGet(() -> firstName + " " + lastName);
                //.orElse(firstName + " " + lastName) - will be executed regardless
        // 9+ jvm hotspot automatically converts string concatenation into string builder
    }
}

// 7
// no setters please
class User {

    private final Permissions permissions;

    void setPermissions(Permissions permissions) {
        this.permissions = permissions
    }
}

class BankAccount {

    enum Status {
        CLOSED, OPEN
    }

    private final Status status;

    void setStatus(Status status) {
        this.status = status;
    }
}

// ----

class User {

    private final Permissions permissions;

    void allowAccess() {
        this.permissions =
    }

    void denyAccess() {
        this.permissions =
    }
}

class BankAccount {

    enum Status {
        CLOSED, OPEN
    }

    private Status status;

    void open() {this.status = Status.OPEN}
    void close() {this.status = Status.CLOSED}
}

// 8
// calling a logic (such as remote system call) in a constructor is a bad idea. Do you know how to fix that?
class SecurePassword  {

    private final String rawPassword;

    private SecurePassword(Vault vault) {
        this.rawPassword = vault.verySecurePassword();
    }

    public String raw() {
        return rawPassword;
    }

}

//-----

class SecurePassword  {

    private final Optional<String> rawPassword;
    private final Vault vault;

    private SecurePassword(Vault vault) {
        this.vault = vault;
    }

    public String raw() {
        if (!rawPassword.ifPresent()) {
            this.rawPassword = vault.verySecurePassword();
        }
        return rawPassword;
    }

}

//
class SecurePassword {
    /*
    @FunctionalInterface
    interface Supplier<T> {
        T get() {}
    }*/
    private final Supplier<String> rawPassword;
    public SecurePassword(Vault vault) {
        // .memoize() - requires GUAVA
        this.rawPassword = memoize(vault::verySecurePassword);
    }
    public String raw(){
        return rawPassword.get();
    }
}