How to find the numbers which are not repeated in array of integers , if others are present twice?

Question

Input- [23,34,56,21,21,56,78,23,34]

Answer 1

yuo can sort it and check if value at i == i+1
or take value and check if it is in this array at some place with higher index
or copy array to arrayList and if you find out duplicities remove it from list

Answer 2

I am not able to implement it, can you please help me with the program?

Answer 3

for first, try to write this:
declare array of int with values
write for() loop
print values from this array, inside this loop

post your code here (or link to your saved sololearn code)