WebElement input = driver.findElement(By.id("username"));
input.clear();
input.sendKeys("alice@example.com");

driver.findElement(By.id("login-btn")).click();

import org.openqa.selenium.support.ui.Select;

Select dropdown = new Select(driver.findElement(By.id("country")));
dropdown.selectByVisibleText("United States");
dropdown.selectByValue("US");
dropdown.selectByIndex(2);

// Get selected option
String selected = dropdown.getFirstSelectedOption().getText();

import org.openqa.selenium.interactions.Actions;

Actions actions = new Actions(driver);

// Hover
actions.moveToElement(driver.findElement(By.id("menu"))).perform();

// Drag and drop
WebElement source = driver.findElement(By.id("drag"));
WebElement target = driver.findElement(By.id("drop"));
actions.dragAndDrop(source, target).perform();

// Click and hold
actions.clickAndHold(source).moveToElement(target).release().perform();

JavascriptExecutor js = (JavascriptExecutor) driver;

// Scroll element into view
js.executeScript("arguments[0].scrollIntoView(true);", element);

// Click via JS (useful when element is covered)
js.executeScript("arguments[0].click();", element);

// Get value
String val = (String) js.executeScript("return document.title;");