How to handle Pop-up in Selenium WebDriver using Java

I want to handle sign-in part in rediff.com, but the below code doesn't work for that:

driver.get("http://www.rediff.com/");
WebElement sign = driver.findElement(By.xpath("//html/body/div[3]/div[3]/span[4]/span/a"));
sign.click();
String myWindowHandle = driver.getWindowHandle();
driver.switchTo().window(myWindowHandle);
WebElement email_id= driver.findElement(By.xpath("//*[@id='signin_info']/a[1]"));
email_id.sendKeys("hi");

If myWindowHandle is not the correct string, then let me know how to get the pop-up Window name, because I can't find the name of the pop-up window.

To switch to a popup window, you need to use getWindowHandles() and iterate through them.

In your code you are using getWindowHandle() which will give you the parent window itself.

String parentWindowHandler = driver.getWindowHandle(); // Store your parent window
String subWindowHandler = null;

Set<String> handles = driver.getWindowHandles(); // get all window handles
Iterator<String> iterator = handles.iterator();
while (iterator.hasNext()){
    subWindowHandler = iterator.next();
}
driver.switchTo().window(subWindowHandler); // switch to popup window

// Now you are in the popup window, perform necessary actions here

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