无效的输入 while 循环字符串

Question

I'm writing a program for a museum ticket system where the user enters the exhibit they would like to visit however when there is invalid input the program skips the if statement and continues the rest of the program.

What im trying do here is make the program loop back to the start of the if statement when input data is invalid.

while(invalidinput){
    if (userinput.equalsIgnoreCase("Roman")) {
        System.out.println("There are " +availabletic.getAvailabletickets1()+ " tickets available for the "+exhibit.getExhibit1());
        System.out.println("");
    } else if (userinput.equalsIgnoreCase("Warhol Art")){
        System.out.println("There are " +availabletic.getAvailabletickets2()+ " tickets available for the "+exhibit.getExhibit2());
        System.out.println("");

    } else if (userinput.equalsIgnoreCase("World War 2")) {
        System.out.println("There are " +availabletic.getAvailabletickets3()+ " tickets available for the "+exhibit.getExhibit3());
        System.out.println("");}

    } else if (!userinput.equalsIgnoreCase("Roman")
            && !userinput.equalsIgnoreCase("Warhol Art") 
            && !userinput.equalsIgnoreCase("World War 2"))
               invalidinput = false; // We signal that we may now leave the loop
       {
       System.out.println("Please enter a valid exhibition name");
    }               
}

Answer 1

This condition:

else if (!userinput.equalsIgnoreCase("Roman")
            && !userinput.equalsIgnoreCase("Warhol Art") 
            && !userinput.equalsIgnoreCase("World War 2"))

must be replaced by:

 else if (!userinput.equalsIgnoreCase("Roman")
            || !userinput.equalsIgnoreCase("Warhol Art") 
            || !userinput.equalsIgnoreCase("World War 2"))

Answer 2

You don't need a catch-all else-if.

if (userinput.equalsIgnoreCase("Roman"))
else if (userinput.equalsIgnoreCase("Warhol Art"))
else if (userinput.equalsIgnoreCase("World War 2"))
else // It's none of the others.