java - Lookup of a number in an array

Question

I wanted to ask what am I doing wrong that is causing the if statement to be false every time I run the program. I've also tried to use .equals(num) instead of the Array.asList(num) to check if the value is in there, but that caused the for loop to repeat the "Not in database" multiple times.

Answer 1

Arrays.asList(Data) creates a list whose only element is an array of int (i.e. List<int[]>). That's why Arrays.asList(Data).contains(num)) always returns false.

Try changing your array to :

Integer Data[] = new Integer[n];

This will make Arrays.asList(Data) create a list of Integer (List<Integer>) containing all the integers of the original array, which is what you need.

The reason for this behavior is the Arrays.asList expects one or more Objects as its input. If you pass an array of Objects (such as Integer[]), it is equivalent to passing multiple Objects. If, however, you pass an array of primitives (such as int[]), the only Object in your input is the array itself, so Arrays.asList() creates a list whose only element is that array.