Beyond Java 8

Angie Jones

https://angiejones.tech

https://TestAutomationU.com

@techgirl1908

Java Champion
Senior Director, Developer Relations
Applitools & Test Automation University

image source: Hendrik Ebbers

@techgirl1908

@techgirl1908

@techgirl1908

@techgirl1908

@Test
public void accountsListed() {

    AccountsOverviewPage accountsOverviewPage =
            page.login(username, password);

    List<String> actualAccounts =
            accountsOverviewPage.getAccounts();

    List<Account> accounts = APIUtil.getAccounts(
    			Customers.getCustomerId(username));

    List<String> expectedAccounts = new ArrayList();
    for(Account account : accounts){
        expectedAccounts
                .add(String.valueOf(account.id()));
    }

    assertEquals(expectedAccounts, actualAccounts);
}

@techgirl1908

@Test
public void accountsListed() {

    AccountsOverviewPage accountsOverviewPage =
            page.login(username, password);

    List<String> actualAccounts =
            accountsOverviewPage.getAccounts();

    List<Account> accounts = APIUtil.getAccounts(
    			Customers.getCustomerId(username));

    List<String> expectedAccounts = new ArrayList();
    for(Account account : accounts){
        expectedAccounts
                .add(String.valueOf(account.id()));
    }

    assertEquals(expectedAccounts, actualAccounts);
}

@techgirl1908

@Test
public void accountsListed() {

    var accountsOverviewPage =
            page.login(username, password);

    List<String> actualAccounts =
            accountsOverviewPage.getAccounts();

    List<Account> accounts = APIUtil.getAccounts(
    			Customers.getCustomerId(username));

    List<String> expectedAccounts = new ArrayList();
    for(Account account : accounts){
        expectedAccounts
                .add(String.valueOf(account.id()));
    }

    assertEquals(expectedAccounts, actualAccounts);
}

TYPE INFERENCE FOR LOCAL VARIABLES

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Java is still a statically typed language

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Initialization is required

var accountsOverviewPage;

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Only works for local variables

public class MyTests {
    var accountsOverviewPage = 
        page. login(username, password);
    
    @Test
    public void accountsListed() {}
}

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Not allowed in headers

public class MyTests {
    
    public MyTests(var data){}
}

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Naming is even more important now

var x = getX();

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Everything doesn't need to be a var!

var numberOfAccounts = 5;

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@Test
public void accountsListed() {

    var accountsOverviewPage =
            page.login(username, password);

    var actualAccountIdsList =
            accountsOverviewPage.getAccounts();

    var accountsList =
            APIUtil.getAccounts(
               Customers.getCustomerId(username));

    var expectedAccountIdsList = new ArrayList<String>();
    for(var account : accountsList){
        expectedAccountIdsList
                .add(String.valueOf(account.id()));
    }

    assertEquals(expectedAccountIdsList, actualAccountIdsList);
}

TYPE INFERENCE FOR LOCAL VARIABLES

@techgirl1908

@Test
public void accountsListed() {

    var accountsOverviewPage =
            page.login(username, password);

    var actualAccountIdsList =
            accountsOverviewPage.getAccounts();

    var accountsList =
            APIUtil.getAccounts(
               Customers.getCustomerId(username));

    var expectedAccountIdsList = new ArrayList<String>();
    for(var account : accountsList){
        expectedAccountIdsList
                .add(String.valueOf(account.id()));
    }

    assertEquals(expectedAccountIdsList, actualAccountIdsList);
}

@techgirl1908

@techgirl1908

public List<String> getAccounts(){

    List<WebElement> accountCells = 
         driver.findElements(accountColumn);
         
    List<String> accounts = new ArrayList();
    for(WebElement element : accountCells){
        accounts.add(element.getText());
    }
    return accounts;   
}

@techgirl1908

public List<String> getAccounts(){

    return driver.findElements(accountColumn)
            .stream()
            .map(WebElement::getText)
            .collect(Collectors.toList());
}

@techgirl1908

public List<String> getAccounts(){

    return driver.findElements(accountColumn)
            .stream()
            .map(WebElement::getText)
            .collect(Collectors.toList());
}
return driver.findElements(accountColumn)
            .stream()
            .map(e -> e.getText())
            .collect(Collectors.toList());

@techgirl1908

@Test
public void accountsListed() {

    var accountsOverviewPage =
            page.login(username, password);

    var actualAccountIdsList =
            accountsOverviewPage.getAccounts();
            
    String customerId = Customers.getCustomerId(username);

    var expectedAccountIdsList =
        APIUtil.getAccounts(customerId)
          .stream()
          .map(Account::getId)
          .map(String::valueOf)
          .collect(Collectors.toList());

    assertEquals(expectedAccountIdsList, actualAccountIdsList);
}

@techgirl1908

New line for

each method call

driver.findElements(accountColumn).stream().map(WebElement::getText).collect(Collectors.toList());
driver.findElements(accountColumn)
        .stream()
        .map(WebElement::getText)
        .collect(Collectors.toList());

@techgirl1908

var accountsList = APIUtil.getAccounts(customerId);
var checkingAccountsList = accountsList
        .stream()
        .takeWhile(account -> account.type().equals("CHECKING"))
        .collect(Collectors.toList());

takeWhile()

var accountsList = APIUtil.getAccounts(customerId);
var checkingAccountsList = accountsList
        .stream()
        .takeWhile(account -> account.type().equals("CHECKING"))
        .collect(Collectors.toList());

takeWhile()

var accountsList = APIUtil.getAccounts(customerId);
var checkingAccountsList = accountsList
        .stream()
        .dropWhile(account -> account.type().equals("CHECKING"))
        .collect(Collectors.toList());

dropWhile()

var accountsList = APIUtil.getAccounts(customerId);
var checkingAccountsList = accountsList
        .stream()
        .dropWhile(account -> account.type().equals("CHECKING"))
        .collect(Collectors.toList());

dropWhile()

dropWhile()

Sort for deterministic results

var accountsList = APIUtil.getAccounts(customerId);

var checkingAccountsList = accountsList
        .stream()
        .sorted(Comparator.comparing(Account::type))
        .takeWhile(account -> account.type().equals("CHECKING"))
        .collect(Collectors.toList());

@techgirl1908

takeWhile() on sorted collection

dropWhile() on sorted collection

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How does this differ from filter?

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@Test
public void accountsListed() {

    var accountsOverviewPage =
            page.login(username, password);

    var actualAccountIdsList =
            accountsOverviewPage.getAccounts();
            
    String customerId = Customers.getCustomerId(username);

	var expectedAccountIdsList =
           APIUtil.getAccounts(customerId)
            .stream()
            .map(Account::getId)
            .map(String::valueOf)
            .collect(Collectors.toList());

    assertEquals(expectedAccountIdsList, actualAccountIdsList);
}

@techgirl1908

public static String getCustomerId(String name){

    String id;
    
    switch(name){
        case "john":
            id = "12212";
            break;
        case "mary":
            id = "4847474";
            break;
        case "tom":
            id =  "293743";
            break;
        default:
            id = "";
            break;
    }
    
    return id;
}

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SWITCH EXPRESSIONS

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public static String getCustomerId(String name) {

    String id = switch(name){
        case "john" -> "12212";
        case "mary" -> "4847474";
        case "tom" -> "293743";
        default    -> "";
    };
    
    return id;
}
public static String getCustomerId(String name){

    return switch(name){
        case "john" -> "12212";
        case "mary" -> "4847474";
        case "tom" -> "293743";
        default -> "";
    };
}

SWITCH EXPRESSIONS

@techgirl1908

public static String getCustomerId(String name) {
  return switch (name) {
    case "john": yield "12212";
    case "mary": yield "4847474";
    case "tom" : yield "293743";
    default    : yield "";
  };
}

SWITCH EXPRESSIONS

@techgirl1908

public static String getCustomerId(String name){

    return switch(name){
        case "john", "demo" -> "12212";
        case "mary" -> "4847474";
        case "tom" -> "293743";
        default -> "";
    };
}

SWITCH EXPRESSIONS

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public static String getCustomerId(String name){

    return switch(name){
        case "john" -> {
            System.out.println("Hi John");
            yield "12212";
        }
        case "mary" -> "4847474";
        case "tom" -> "293743";
        default -> "";
    };
}

SWITCH EXPRESSIONS

@techgirl1908

Cannot mix and match -> and :yield

return switch(name){
    case "john" -> "12212";
    case "mary": yield "4847474";
    case "tom" -> "293743";
    default -> "";
};

@techgirl1908

Can throw Exceptions

return switch(name){
    case "john" -> "12212";
    case "mary" -> "4847474";
    case "tom" -> "293743";
    default -> throw new InvalidNameException();
};

@techgirl1908

When to use expressions vs statements?

@techgirl1908

@Test
public void accountsListed() {

    var accountsOverviewPage =
            page.login(username, password);

    var actualAccountIdsList =
            accountsOverviewPage.getAccounts();
            
    String customerId = Customers.getCustomerId(username);

    var expectedAccountIdsList =
        APIUtil.getAccounts(customerId)
          .stream()
          .map(Account::getId)
          .map(String::valueOf)
          .collect(Collectors.toList());

    assertEquals(expectedAccountIdsList, actualAccountIdsList);
}

@techgirl1908

public class APIUtil {

  public static List<Account> getAccounts(String customerId){
      return Arrays.asList(given()
          .header(new Header("Accept", "application/json"))
          .get(format(GET_ACCOUNTS, customerId))
          .as(Account[].class));
  }
}

@techgirl1908

[
  {
    "id": 13344,
    "customerId": 12212,
    "type": "CHECKING",
    "balance": 4022.93
  },
  {
    "id": 13455,
    "customerId": 12212,
    "type": "CHECKING",
    "balance": 1000
  }
]

@techgirl1908

public class Account {

    private int id;
    private int customerId;
    private String type;
    private double balance;

    public int getId() { return id; }
    public void setId(int id) { this.id = id; }

    public int getCustomerId() { return customerId; }
    public void setCustomerId(int customerId) { 
    	this.customerId = customerId; 
    }

    public String getType() { return type; }
    public void setType(String type) { this.type = type; }
    
    public double getBalance() { return balance; }
    public void setBalance(double balance) { 
    	this.balance = balance; 
    }
}

@techgirl1908

public record Account(
       int id,
       int customerId,
       String type,
       double balance){}

RECORDS

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public record Account(
       int id,
       int customerId,
       String type,
       double balance
){
    @Override
    public String toString(){
        return "I've overriden this!";
    }
}

RECORDS

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Records can be instantiated

Account account = new Account(
    13344, 12212, "CHECKING", 4033.93);

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Records are immutable

Account account = new Account(
    13344, 12212, "CHECKING", 4033.93);
    
account.setType("SAVINGS");

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Accessors don't start with get

Account account = new Account(
    13344, 12212, "CHECKING", 4033.93);
    
double balance = account.balance();

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Inheritance is not supported.

record CheckingAccount() extends Accounts 
{
    
}

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Records can implement interfaces

@techgirl1908

public interface AccountInterface {
    
    void someMethod();
}

public record Account(
        int id,
        int customerId,
        String type,
        double balance) implements AccountInterface
{
    public void someMethod(){
        
    }
}

@techgirl1908

@Test
public void accountsListed() {

    var accountsOverviewPage =
            page.login(username, password);

    var actualAccountIdsList =
            accountsOverviewPage.getAccounts();
            
    String customerId = Customers.getCustomerId(username);

    var expectedAccountIdsList =
        APIUtil.getAccounts(customerId)
          .stream()
          .map(Account::getId)
          .map(String::valueOf)
          .collect(Collectors.toList());

    assertEquals(expectedAccountIdsList, actualAccountIdsList);
}

@techgirl1908

[
  {
    "id": 13344,
    "customerId": 12212,
    "type": "CHECKING",
    "balance": 4022.93
  },
  {
    "id": 13455,
    "customerId": 12212,
    "type": "CHECKING",
    "balance": 1000
  }
]

@techgirl1908

String response = 
"[\n" +
"  {\n" +
    "    \"id\": 13344,\n" +
    "    \"customerId\": 12212,\n" +
    "    \"type\": \"CHECKING\",\n" +
    "    \"balance\": 4022.93\n" +
    "  },\n" +
    "  {\n" +
    "    \"id\": 13455,\n" +
    "    \"customerId\": 12212,\n" +
    "    \"type\": \"CHECKING\",\n" +
    "    \"balance\": 1000\n" +
    "  }\n" +
    "]";

@techgirl1908

public String getAccounts_mocked(){
    return """
            [
              {
                "id": 13344,
                "customerId": 12212,
                "type": "CHECKING",
                "balance": 3821.93
              },
              {
                "id": 13455,
                "customerId": 12212,
                "type": "LOAN",
                "balance": 989
              }
            ]
            """;
}

TEXT BLOCKS

@techgirl1908

Text cannot begin on

same line as """



System.out.println(""" Hey y'all! """);


System.out.println(""" 
                   Hey y'all!""");
                   

System.out.println(""" 
                   Hey y'all!
                   """);                   
@Test
public void accountsListed() {

    var accountsOverviewPage =
            page.login(username, password);

    var actualAccountIdsList =
            accountsOverviewPage.getAccounts();
            
    String customerId = Customers.getCustomerId(username);

    var expectedAccountIdsList =
        APIUtil.getAccounts(customerId)
          .stream()
          .map(Account::getId)
          .map(String::valueOf)
          .collect(Collectors.toList());

    assertEquals(expectedAccountIdsList, actualAccountIdsList);
}

@techgirl1908

public static List<String> getAccountIds_mocked(){
    return Arrays.asList("13344", "13455", "13566", "14010");
}
public static List<String> getAccountIds_mocked(){
    return List.of("13344", "13455", "13566", "14010");
}

COLLECTION CONVENIENCE METHOD

@techgirl1908

image source: Hendrik Ebbers

Map users = new HashMap();
users.put("john", 123);
users.put("alice", 456);
users.put("sue", 789);
Map users = Map.of("john", 123, "alice", 456, "sue", 789);

COLLECTION CONVENIENCE METHOD

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The of() method creates immutable collections

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Map users = Map.of(
   "john", 123, 
   "alice", 456, 
   "sue", 789);
users.put("bob", 000);
users.remove("alice");

COLLECTION CONVENIENCE METHOD

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Thank you!

@techgirl1908

Beyond Java 8

Angie Jones

https://angiejones.tech

https://TestAutomationU.com

@techgirl1908

Java Champion

Senior Director, Developer Relations

Applitools & Test Automation University

Modern Java: Beyond Version 8

By Angie Jones

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