Java all determine elements are same in a list

Question

I am trying to determine to see if all elements in a list are same. such as:

(10,10,10,10,10) --> true (10,10,20,30,30) --> false 

I know hashset might be helpful, but i don't know how to write in java.

this is the one I've tried, but didn't work:

public static boolean allElementsTheSame(List<String> templist)  {      boolean flag = true;     String first = templist.get(0);      for (int i = 1; i< templist.size() && flag; i++)     {         if(templist.get(i) != first) flag = false;     }      return true; } 

Answer 1

Using the Stream API (Java 8+)

boolean allEqual = list.stream().distinct().limit(2).count() <= 1 

or

boolean allEqual = list.isEmpty() || list.stream().allMatch(list.get(0)::equals); 

Using a Set:

boolean allEqual = new HashSet<String>(tempList).size() <= 1; 

Using a loop:

boolean allEqual = true; for (String s : list) {     if(!s.equals(list.get(0)))         allEqual = false; } 

Issues with OP's code

Two issues with your code:

• Since you're comparing Strings you should use !templist.get(i).equals(first) instead of !=.

• You have return true; while it should be return flag;

Apart from that, your algorithm is sound, but you could get away without the flag by doing:

String first = templist.get(0); for (int i = 1; i < templist.size(); i++) {     if(!templist.get(i).equals(first))         return false; } return true; 

Or even

String first = templist.get(0); for (String s : templist) {     if(!s.equals(first))         return false; } return true;