CODEWITHSUNDEEP
java
Sanito Machiavelli
Sanito Machiavelli

Reputation: 133

Java scanner with integer validation

What is the correct syntax to get Integers from scanner if they meet some criteria and assign to arrayList? It should loop and get the inputs until we insert "-1". It stops then I insert "q" but I need it to work with certain integer.

              Scanner sc = new Scanner(System.in);
              while (-99 !== sc.nextLine() && sc.hasNextInt()) 
              {
              //do something Whi
              }

Upvotes: 0

Views: 123

Answers (4)

Lakshmikant Deshpande
Lakshmikant Deshpande

Reputation: 844

This will loop until -1 is encountered, and add the elements to the arraylist. Let me know if you need any help in this.

List<Integer> list = new ArrayList<>();
Scanner scanner = new Scanner(System.in);

// keep looping until -1 is encountered
while (true) {
        int temp = scanner.nextInt();
        if (temp == -1) {
            break;
        }
        list.add(temp);
}

// Printing the array list
System.out.println(list);

// closing the scanner is important
scanner.close();

Upvotes: 1

sepehr hakimi
sepehr hakimi

Reputation: 21

sc if a refrence to a object of Scanner class and not compaire with int object. you must check the value of next int in your while loop

Upvotes: 0

mrinal
mrinal

Reputation: 375

You probably want to do this: 

Scanner sc = new Scanner(System.in);
int num;
do{
    while (!sc.hasNextInt()){
        sc.next();
    }
    num = sc.nextInt();
}while(num!=-1)

Hope this helps!

Upvotes: 1

Scary Wombat
Scary Wombat

Reputation: 44834

I am not sure exactly what your requirements are but how about

Scanner sc = new Scanner(System.in);
while (true) 
{
    int numEntered = sc.nextInt ();
    if (numEntered  == -1) {
        break;
    }
    // do something
}

Upvotes: 1

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