Java ArrayList contains method , small problem?

Question

I am trying to prevent the user from entering a duplicate value for an arrayList , I think this is the correct way to do it. I believe its my if statement that does not work, I tried userNums.get(i).contains(userNums), but that will not work.

int i = 0;
       while(i < 5)
       {
           System.out.println("&#92;nEnter a number for the lottery, you may not enter a duplicate: ");         
           userNums.add(kb.nextInt()); 
            
           if(!userNums.contains(userNums)) 
           {
               i++;
           }   
           else{
              System.out.println("You entered a duplicate number try again: ");
           }
       }

Person Of Blah · Accepted Answer

Try something like this instead: 
System.out.println("&#92;nEnter a number for the lottery, you may not enter a duplicate: "); 
int x = kb.nextInt();
if(userNums.contains(x)){
System.out.println("Error");
}
else{
userNums.add(x);
i++;
}
}

The reason your code doesn't work is because the method "contains()" is expecting an integer argument, not another ArrayList. Also, the way you have it set up, you would still need to remove the number after detecting the error. The way I have outlined, the check is done before adding the number to the ArrayList.

Hope that helps!

? · Answer

Java Arraylist Contains

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Java ArrayList contains method , small problem?

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