I have a scenario in which clicking on "Save" button can give three different alerts based on the data entered. It can give "Saved successfully", "User already registered" and "Username already exist" alerts. I have tried:
driver.findElement(By.id("dnn_ctr5995_View_btnsavesession")).click();
    Thread.sleep(10000);
Alert alert = driver.switchTo().alert();
    String A = alert.getText();
    if (A == "Username already exist"){
        System.out.println("Admission number already exist.");
        alert.accept();
    } else if (A == "User already registered"){
        System.out.println("User already registered");
        alert.accept();
    } else if (A == "Saved Successfully."){
        System.out.println("Saved Successfully.");
        alert.accept();
    }
But it is showing No Alert present exception. I have tried increasing the sleep time but still it shows the same exception.