Java for Testers Interview Questions for 1 Year Experience (2026)

Short answer: == checks whether two references point to the same object; equals() checks whether the text is the same. In tests, always compare expected and actual text with equals() (or an assertion library, which calls it for you).

String a = "Login";
String b = new String("Login");
System.out.println(a == b);       // false - two different objects
System.out.println(a.equals(b));  // true  - same characters

Common failure: driver.getTitle() == "Dashboard" fails even when the title looks right, because the browser returns a new String object.

Short answer: checked exceptions (such as IOException) must be caught or declared with throws; unchecked exceptions extend RuntimeException and are not forced by the compiler. Selenium's NoSuchElementException and TimeoutException are unchecked.

When you read a test-data file, use try-with-resources so the file is always closed:

try (BufferedReader reader = Files.newBufferedReader(Path.of("users.csv"))) {
    String header = reader.readLine();
    System.out.println(header);
} // reader.close() runs automatically, even if readLine throws

Common failure: wrapping a whole test in catch (Exception e) {}. The test then passes when it should fail.

Short answer: a static field belongs to the class, so every object (and every thread) shares one copy. A static WebDriver works when tests run one at a time, but once tests run in parallel, two tests drive the same browser and fail randomly.

public class BaseTest {
    protected WebDriver driver;          // one per test instance

    @BeforeMethod
    public void setUp() { driver = new ChromeDriver(); }

    @AfterMethod
    public void tearDown() { driver.quit(); }
}

Static is fine for constants (static final String BASE_URL) and small helper methods that keep no state.

Short answer: keep locators private and expose public actions. Tests then say what the user does, and a locator change touches one class only.

public class LoginPage {
    private final WebDriver driver;
    private final By email = By.id("email");
    private final By password = By.id("password");
    private final By submit = By.cssSelector("button[type='submit']");

    public LoginPage(WebDriver driver) { this.driver = driver; }

    public void loginAs(String user, String pass) {
        driver.findElement(email).sendKeys(user);
        driver.findElement(password).sendKeys(pass);
        driver.findElement(submit).click();
    }
}

The four levels are private (class only), package-private (no keyword), protected (package and subclasses) and public.

Short answer: use a List when order matters or duplicates are allowed (rows in a table), a Set when you need unique values (checking a dropdown has no duplicate options), and a Map for key-value data (column name to cell value).

List<String> options = List.of("India", "Japan", "India");
Set<String> unique = new HashSet<>(options);
System.out.println(options.size() == unique.size()); // false - a duplicate exists

Note that HashSet and HashMap do not keep insertion order. Use LinkedHashSet/LinkedHashMap when the order must match what the page shows.

Short answer: the for-each loop uses an iterator, and changing the list directly while iterating makes the iterator fail fast. Use removeIf or the iterator's own remove().

List<String> names = new ArrayList<>(List.of("a", "", "b", ""));

// for (String n : names) if (n.isEmpty()) names.remove(n);  // throws ConcurrentModificationException

names.removeIf(String::isEmpty);
System.out.println(names); // [a, b]

This is a common screening question for junior automation roles. Explain the idea first: walk through the characters and keep a count in a map.

import java.util.LinkedHashMap;
import java.util.Map;

public class CharCount {
    public static void main(String[] args) {
        String input = "testing";
        Map<Character, Integer> counts = new LinkedHashMap<>();
        for (char ch : input.toCharArray()) {
            counts.merge(ch, 1, Integer::sum);
        }
        System.out.println(counts); // {t=2, e=1, s=1, i=1, n=1, g=1}
    }
}

Mention the edge cases you would test: empty string, upper vs lower case, and spaces.

Short answer: a String cannot change after it is created; every + makes a new object. Inside a loop that builds a long text (for example a CSV report), use StringBuilder.

StringBuilder report = new StringBuilder("test,status\n");
for (String test : List.of("login", "search")) {
    report.append(test).append(",PASS\n");
}
System.out.print(report);

Expected output: three lines - the header, then login,PASS and search,PASS.