Why does A == A evaluates to false?

Question

I'm working on a Java program that takes an input String called input which looks like

'(A A A A B C C D E E E E)

And my output, A String[] called Letters that should look like

[A,B,C,D,A,E]

And another Array, an int[] called count that should look like

[4,1,2,1,2,4]

And I have code that looks like below, but for some reason, every time I run it it won't work. The print statements read that it doesn't ever go to the if statement. Line 2 on the second loop reads:

Check if A == A

Then it goes to the else statement and prints

A != A

What am I doing wrong? Why is A (items[0]) not equal to A (checkagainst)?

 private static boolean func2(String input){ /*input: '(A A A A B C C D E E E E)
    input = input.replace("'","");//replace to null char
    input = input.replace("(","");//replace to null char
    input = input.replace(")","");//replace to null char
    System.out.println(input);
    String[] items = input.split(" |\u0000",0);
    System.out.println("Array items "+Arrays.toString(items));

    int position = 0;
    int countlength = 0; for (String z: items)countlength += 1;//determines the MAX length of the letters array
    String checkagainst = "";
    String[] letters = new String[countlength];
    int[] count = new int[countlength];
    System.out.println("\n Letters: "+Arrays.toString(letters)
            +"\nCount: "+Arrays.toString(count)
            +"\nItems: "+Arrays.toString(items));
    for (int x = 0; x < items.length; x++){
        System.out.println("\n\nCheck if"+checkagainst+"=="+items[x]);
        if (checkagainst == items[x]){
            count[position] += 1;
            System.out.println("Iteration:" + x
                    +"\n Letters: "+Arrays.toString(letters)
                    +"\n Count: "+Arrays.toString(count)
                    +"\nSwitch: if");
        }
        else{
            System.out.println("checkagainst != items[x]");
            letters[position] = items[x];
            count[position] = 1;
            checkagainst = items[x];
            position ++;
            System.out.println("Iteration:" + x
                                +"\n Letters: "+Arrays.toString(letters)
                                +"\n Count Arrays"+Arrays.toString(count)
                                +"\ncheckagainst: "+ checkagainst
                                +"\nSwitch: else");
        }
    }