How to create a class method with conditional return type

Question

Please excuse terminology issues in this post. This appears to be a basic Java question, I just am not finding results in my searching.

I would like to create a method that could potentially return multiple types in a Selenium pageObject framework. See example below:

public class ProductPage extends BasePage {
    public ProductPage(WebDriver driver) {
         super(driver);
    }

    public ProductPage enterValue(String inputText) {
         driver.findElement(By.id("someId")).sendKeys(inputText);
         return this;
    }

The method enterValue occasionally lands to a different page than ProductPage. If I know it could navigate elsewhere, I tend to create a different method. However, this is making the tests harder for others to understand and maintain.

Is there a way to obfuscate the return type and add a conditional inside the method that allows the method to return a different type? Here is my best attempt:

public NotSureWhatToPutHere enterValue(String inputText) {
     driver.findElement(By.id("someId")).sendKeys(inputText);
     if(isAlertPresent){
          return new ProductAlertPage(driver);
     } else if (isErrorDisplayed) {
          return new ErrorPage(driver);
     } else {
          return this;
     }
}

Answer 1

You need to use polymorphism or inheritance.

so ProductAlertPage and ErrorPage both inherit from an interface or class like eg Page . Then you can have a return type of Page .

---

In your case ErrorPage and ProductAlertPage should also extend BasePage and then you can return BasePage as return type.

public BasePage enterValue(String inputText) {
  driver.findElement(By.id("someId")).sendKeys(inputText);
    if(isAlertPresent){
      return new ProductAlertPage(driver);
    } else if (isErrorDisplayed) {
      return new ErrorPage(driver);
    } else {
      return this;
   }
}

Answer 2

You can try :

public Page enterValue(String inputText) {

}

Where is Page is extended by both ProductAlertPage and ErrorPage .

public ProductAlertPage extends Page {
    // code for ProductAlertPage
}

public ErrorPage extends Page {
   // code for ErrorPage
}

Alternatively, you can also make Page an interface and have both ProductAlertPage and ErrorPage implements the interface as shown below:

public ProductAlertPage implements Page {
    // code for ProductAlertPage
}

public ErrorPage implements Page {
   // code for ErrorPage
}

This is a better solution as it is less tightly coupled.