How Can I get input from user until user enter the right input in java?

Question

i try to make a menu in java and get user input Until user enter the right input, so i used while() in my code. but when i run my code , the only things is run is while loop for whole time that i enter input , even the right input.

//Show Menu Of Languages
    System.out.print("Welcome To iHome Application \n \n Pleas Choose You're Wanted Language" +
            "(Enter Number Of Language Or Type You're Wanted Language) : \n 1)English \n or \n 2)Persian " + "\n \n");
    //Get Input From User
    Scanner input = new Scanner(System.in);
    String MenuLanguage = input.next();
    //Get User Language Until User Enter The Right Format
    while (!MenuLanguage.equalsIgnoreCase("1") || (!MenuLanguage.equalsIgnoreCase("English")) ||
            (!MenuLanguage.equalsIgnoreCase("2")) || (!MenuLanguage.equalsIgnoreCase("Persian")) )  {
        System.out.print("\n Pleas Enter An Option From Above Menu. Try Again. \n");
        MenuLanguage = input.next();
    }
        if ((MenuLanguage.equalsIgnoreCase("1")) || (MenuLanguage.equalsIgnoreCase("English"))) {

        } else if ((MenuLanguage.equalsIgnoreCase("2")) || (MenuLanguage.equalsIgnoreCase("Persian"))) {
            System.out.print("Sorry. Persian Language Will Be Available Soon.");
        }

but always my output is : "Pleas Enter An Option From Above Menu. Try Again."

whats is my problem?

but why i should use "And" instead of "Or"? when i'm tried to say if one condition was true. — Ali Akhtari
– Ali Akhtari, Commented Mar 1, 2018 at 14:11
You tried the opposite: If one condition is false, which is always true. — Chris311
– Chris311, Commented Mar 1, 2018 at 14:14

Chuk Ultima · Accepted Answer · 2018-03-01 14:13:12Z

2

In your while loop, you check for OR (||). Replace it by AND (&&)

while (!MenuLanguage.equalsIgnoreCase("1") && (!MenuLanguage.equalsIgnoreCase("English")) &&
            (!MenuLanguage.equalsIgnoreCase("2")) && (!MenuLanguage.equalsIgnoreCase("Persian")) )

A condition cannot meet OR with different input. If it's one thing, it will not be the 3 other things. With and, you can check it's neither of the 4 conditions.

edited Mar 1, 2018 at 14:13

answered Mar 1, 2018 at 14:09

Chuk Ultima

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5 Comments

Ali Akhtari Over a year ago

Thanks.but why i should use "And" instead of "Or"? when i'm tried to say if one condition was true?

Chuk Ultima Over a year ago

A condition cannot meet OR with different input. If it's one thing, it will not be the 3 other things. With and, you can check it's neither of the 4 conditions. With the OR, only one condition needs to be True for the condition to consider the True path.

Ali Akhtari Over a year ago

i cant understand , I'm trying to say of one of four condition was true , do something, not if all of my conditions was true. When i use " || " i say just one of my condition and when i use "&&" i say that is all of my conditions was true , and its cant be happen , because it isn't possible that one String is equal to four string together in one time.

Chuk Ultima Over a year ago

I'll make an analogy : Imagine you have an apple you checked : if it's not a pear or not a kiwi or not a banana do something. But no matter what fruit you pass to that condition, it will never be 2 different fruits at once. So at least 2 out of those 3 conditions will say True. And if any of the conditions in an OR check says True, it passes.

Ali Akhtari Over a year ago

i got it. Thanks

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