Why StringBuilder's delete shifts string to the left and does not delete the last character?

I'm new here.
I'm trying to figure out how to delete the last character in the string but I'm not succeeding.
I use my code - in StringBuilder.

For example I have a string of 'abcde'
i want to get after delete the first character - the String bcde
but i got the string bcdee.
All the time I keep deleting - the last character is not deleted
I want to delete the first character in the string and leave nothing at the end.

		StringBuilder test = new StringBuilder();
		test.append("abcde");
		test.deleteCharAt(0);
		test.deleteCharAt(0);
		test.deleteCharAt(0);
		test.deleteCharAt(0);

After running this code
I get: I want to get:

bcdee    bcde
cdeee    cde
deeee    de
eeeee    e

> I'm trying to figure out how to delete the last character in the string.

To delete the last character in a String:

String s = someString.substring(0, someString.length() - 1)

Note that a String is ummutable, so the above is actually creating a new String.

To remove the last character in a StringBuilder:

someStringBuilder.setLength(someStringBuilder.length() - 1);

You can also remove the last character using

someStringBuilder.deleteCharAt(someStringBuilder.length() - 1);

The above code fragments all assume that there is a last character to be removed.

Your code calls deleteCharAt(0). That deletes the first character not the last one.

But your example seems to require you to remove duplicate characters at the end of a string. To do that, you need a loop:

pseudocode

while last character equals second to last character:
    remove last character

See if you can code that for yourself ...

First of all, your code:

    StringBuilder test = new StringBuilder();
    test.append("abcde");
    System.out.println(test);
    test.deleteCharAt(0);
    System.out.println(test);
    test.deleteCharAt(0);
    System.out.println(test);
    test.deleteCharAt(0);
    System.out.println(test);
    test.deleteCharAt(0);
    System.out.println(test);

outputs:

abcde
bcde
cde
de

which is correct, as expected, without any additional es, as you mention it in the original question. So, try to figure out what you have additionally in your code that causes this.

>Why delete in StringBuilder shift string to left and doesn't delete the last character?

It shifts, because, by test.deleteCharAt(0);, you explicitly tell Java to delete Char at specific (0, in this case) index, hence the new String will not be starting with an empty character; however, it should nt and it does not remove the last character, and the last extra character is simply never appended (there is no extra e).

Apart from the .setLength() and .subString(), you can simply use the same .deleteCharAt(int) API and do as follows:

    StringBuilder test = new StringBuilder();
    test.append("abcde");
    System.out.println(test);
    test.deleteCharAt(test.length()-1);
    System.out.println(test);
    test.deleteCharAt(test.length()-1);
    System.out.println(test);
    test.deleteCharAt(test.length()-1);
    System.out.println(test);
    test.deleteCharAt(test.length()-1);
    System.out.println(test);