How to handle null point exception while using switch strings

package newpackage;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.openqa.selenium.ie.InternetExplorerDriver;


public class Launchbrowsers {

      public static void main(String[] args)throws Exception {
            
            Browser("Chrome");
            Browser("IE");
            Browser("Firefox");
            
            }
            
      public static void Browser(String Launcher) {
            
            switch(Launcher){
            case "Chrome":
                  String file1 = System.getProperty("user.dir")+"/lib/chromedriver.exe";
                  System.setProperty("webdriver.chrome.driver",file1);
                  WebDriver driver1 = new ChromeDriver();
                  driver1.get("https://apple.com/");
                  driver1.close();
                  System.out.println("Chrome is successfully launched and closed");
                  break;
                  
            case "IE":
                  
                  String file2 = System.getProperty("C:/Users/newproject/lib/IEDriverServer.exe");
                  System.setProperty("webdriver.ie.driver", file2);
                  WebDriver driver2 = new InternetExplorerDriver();
                  driver2.get("https://apple.com/");
                  driver2.close();
                  System.out.println("InternetExplorer is successfully launched and closed");
                  break;
                  
            case "Firefox":
                  String file3 = System.getProperty("user.dir")+"/lib/geckodriver.exe";
                  System.setProperty("webdriver.gecko.driver",file3);
                  WebDriver driver3 = new FirefoxDriver();
                  driver3.get("https://apple.com/");
                  driver3.close();
                  System.out.println("Firefox is successfully launched and closed");
                  break;
                  
            default:
                  System.out.println("Errors in browser + driver configuration");
                  break;
            }
            }
}
            
I thought I had attached the .java file here. Sorry, here's the program I'm trying to execute.