Question

In my Java application i need to compare two list’s element whether it is similar or not.

In short suppose i have two list declared like shown below

List<String> a = new ArrayList<String>();
    a.add("one");
    a.add("three");
    a.add("two");
Collections.sort(a);


List<String> a1 = new ArrayList<String>();
    a1.add("ONE");
    a1.add("two");
    a1.add("THREE");
Collections.sort(a);

If i write a condition for equality it fails as some of list’s element is in different case like

if(a.equals(a1)){
    System.out.println("equal");
} else{
    System.out.println("not equal");
}

It will display result “Not equal”

So please tell me how i can make the list element case-insensitive in Java language only.

Thank and regard

Answer 1

Why not using instead a SortedSet with a case insensitive comparator ?
With the String.CASE_INSENSITIVE_ORDER comparator

Your code is reduced to

Set<String> a = new TreeSet<String>(String.CASE_INSENSITIVE_ORDER);
    a.add("one");
    a.add("three");
    a.add("two");


Set<String> a1 = new TreeSet<String>(String.CASE_INSENSITIVE_ORDER);
    a1.add("ONE");
    a1.add("two");
    a1.add("THREE");

And your equals conditions should work without any issue

EDIT modified according to comments. Thanks to all of you to correct me.