How to handle WebPopups/tabs/new Windows in Selenium Webdriver?

click on something to get the another window/popup
//fetch all the window ids
Set<String>handles=driver.getWindowHandles();

//using Iterator interface
Iterator it=handles.iterator();
//fetchign main window id
String pid=(String)it.next();
//fetching the child window id
String chwinid=(String)it.next();
//switch to the child window id
driver.switchTo().window(windowref);
driver.switchTo().window(chwinid);
//perform the actions on the child window;
//close the child window
driver.close();
//switch back the cursor to parent window from childwindow
driver.switchTo().window(pid);
-----------------------------------------------------------------
2nd Way:based on the window title
//fetch the parent window id
String pid=driver.getWindowHandle();
click on something to get the another window/popup

//fetch all the window ids
Set<String>handles=driver.getWindowHandles();

for(String h:handles){
//if(!pid.equal(h){
if(driver.switchTo().window(h).getTitle().equals("windowtitle")){
//switch to that window
driver.switchTo().window(h);
//perform the actions on the window
} //end the if
 }//for loop end

 //close the child browser
 driver.close();

 //switch to parent window from child window
 driver.switchTo().window(pid);
 ============================================
 //using iterator while loop
 String pid=driver.getWindowhandle();
 //fetch all window ids
 Set<String>handles=driver.getWindowHandles();
 Iterator it=handles.iterator();
 while(it.hasNext()){

 if(!pid.equals(it.next())){
 //switch to child window
 driver.switchTo().window(it.next());
 close the child window
 driver.close();
 }
 }
 //switch to the parent window
 driver.switchTo().window(pid);

(OR)
for(String h:handles) {
if(!pid.equals(h)) {
driver.switchTo().window(h);
driver.close();
}
}

//switch back to parent window
driver.switchTo().window(pid);

============================================

There are 5 windows and I need to switch to 3rd window 

and verify the checkout button in the 3rd window and close the 3rd window

 and then come back to parent window 

 and type something in the parent window?

step1: fetch all the window ids

String pid=driver.getWindowHandle();

Set<String>handles=driver.getWindowHandles();

//convert the Set collection into List

List<String>windowsList=new ArrayList(handles);

step2-switch to 3rd window

driver.switchTo().window(windowsList.get(2));

WebElement checkoutBtn=driver.findElement(By.id("checkout"));

Assert.assertTrue(checkoutBtn.isDisplayed));

//close the child window

driver.close();

//swithc back to parent window.

driver.switchTo().window(windowsList.get(0));

driver.switchTo().defaultContent();

//now do action on prent page searcheditbox /log0 

driver.findElement(By.id("searchEditboix")).sendKeys("selenium");

================================================================

i have a login page clicked terms and condiitons link window click close button and 

licence agreement window accept it then come back to main window then type credentials

step1:fetch the parent window

String pid=driver.getWindowHandle();

click on terms & conditions link

driver.findElement(By.linkText("terms & conditions")).click();

click on license agreement link

driver.findElement(By.linkText("license agreement")).click();

Step4:fetch all window ids

Set<String>handles=driver.getWindowHandles();

for(String h:handles){

if(!pid.equals(h)){

if(driver.switchTo.window(h).getTitle().equals("terms & conditions")){

//switch to Terms & Conditions window 

driver.switchTo.window(h);

//click on close button

driver.findElement(By.xpath("//*[text()='close']")).click();

}else if(driver.switchTo.window(h).getTitle().equals("LicenseAgreement")){

//switch to LicenseAgreement window 

driver.switchTo.window(h);

//Accept the licence agreement radio button

driver.findElement(By.xpath("//*[text()='close']")).click();

}

//close the child window

driver.close();

}

}

//switch back to parent window.

driver.switchTo().window(pid);

//type the username.

driver.findElement(By.id("username")).sendkeys("rameshn3");

//type the password in password editbox

driver.findElement(By.name("password")).sendkeys(""test123);

//click on login button.

driver.findElement(By.xpath("//*[@type='submit']")).click();

================================================================

SELENIUM4 FEATURE OPENING NEW TAB AND NEW WINDOW  PROGRAM

package junitprograms;

import static org.junit.jupiter.api.Assertions.*;

import java.time.Duration;

import java.util.Iterator;

import java.util.List;

import java.util.Set;

import org.junit.jupiter.api.AfterAll;

import org.junit.jupiter.api.AfterEach;

import org.junit.jupiter.api.Assertions;

import org.junit.jupiter.api.BeforeAll;

import org.junit.jupiter.api.BeforeEach;

import org.junit.jupiter.api.Test;

import org.openqa.selenium.Alert;

import org.openqa.selenium.By;

import org.openqa.selenium.NoSuchFrameException;

import org.openqa.selenium.WebDriver;

import org.openqa.selenium.WebElement;

import org.openqa.selenium.WindowType;

import org.openqa.selenium.chrome.ChromeDriver;

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

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

class Selenium4OpeninginNewTabAndNewWindow {

private static WebDriver driver = null;

private static WebDriverWait wait = null;

String pid=null;

@BeforeAll

static void setUpBeforeClass() throws Exception {

System.setProperty("webdriver.chrome.driver",

"D:\\webdriverjars\\executables\\chrome99\\chromedriver_win32\\chromedriver.exe");

// interface variablename=new classname();

driver = new ChromeDriver();

// maximize the window

driver.manage().window().maximize();

// add implicit wait

driver.manage().timeouts().implicitlyWait(Duration.ofSeconds(10));

// create WebDriverWaitobject

wait = new WebDriverWait(driver, Duration.ofMillis(30000));

// launch the application url

driver.get("http://the-internet.herokuapp.com/");

// wait for the page title

wait.until(ExpectedConditions.titleContains("The Internet"));

Assertions.assertEquals("The Internet", driver.getTitle());

Assertions.assertTrue(driver.getTitle().contains("The Internet"));

// verify the page heading

wait.until(ExpectedConditions.presenceOfElementLocated(By.cssSelector("h1.heading")));

String headingTxt = driver.findElement(By.cssSelector("h1.heading")).getText();

Assertions.assertEquals("Welcome to the-internet", headingTxt);

// Click on Multiple Windows link

driver.findElement(By.partialLinkText("Multiple Windows")).click();

}

@AfterAll

static void tearDownAfterClass() throws Exception {

if (driver != null) {

driver.quit();

}

}

@Test

void testOpenNewTab() throws InterruptedException {

System.out.println(" testOpenNewTab()::::");

// Verify the login page Addressbar url and page heading

wait.until(ExpectedConditions.urlContains("/windows"));

wait.until(ExpectedConditions.presenceOfElementLocated(By.cssSelector("div[class='example']>h3")));

String windowheadertxt = driver.findElement(By.cssSelector("div[class='example']>h3")).getText();

Assertions.assertEquals("Opening a new window", windowheadertxt);

   pid=driver.getWindowHandle();

driver.switchTo().newWindow(WindowType.TAB);

Thread.sleep(3000);

driver.navigate().to("https://linkedin.com");

Thread.sleep(3000);

//close the tab

driver.close();

//switch back to parentwindow

driver.switchTo().window(pid);

driver.switchTo().defaultContent();

String windowheadertxt1 = driver.findElement(By.cssSelector("div[class='example']>h3")).getText();

Assertions.assertEquals("Opening a new window", windowheadertxt1);

Thread.sleep(3000);

}

@Test

void testOpenNewWindow() throws InterruptedException {

System.out.println(" testOpenNewWindow()::::");

// Verify the login page Addressbar url and page heading

wait.until(ExpectedConditions.urlContains("/windows"));

wait.until(ExpectedConditions.presenceOfElementLocated(By.cssSelector("div[class='example']>h3")));

String windowheadertxt = driver.findElement(By.cssSelector("div[class='example']>h3")).getText();

Assertions.assertEquals("Opening a new window", windowheadertxt);

pid=driver.getWindowHandle();

driver.switchTo().newWindow(WindowType.WINDOW);

Thread.sleep(3000);

driver.navigate().to("https://facebook.com");

Thread.sleep(3000);

//close the tab

driver.close();

//switch back to parentwindow

driver.switchTo().window(pid);

driver.switchTo().defaultContent();

String windowheadertxt1 = driver.findElement(By.cssSelector("div[class='example']>h3")).getText();

Assertions.assertEquals("Opening a new window", windowheadertxt1);

Thread.sleep(3000);

}

}