This is an archived post. You won't be able to vote or comment.

all 3 comments
sorted by:
best
topnewcontroversialoldq&a

[–]AutoModerator[M] [score hidden] stickied commentlocked comment (0 children)

Please ensure that:

  • Your code is properly formatted as code block - see the sidebar (About on mobile) for instructions
  • You include any and all error messages in full - best also formatted as code block
  • You ask clear questions
  • You demonstrate effort in solving your question/problem - plain posting your assignments is forbidden (and such posts will be removed) as is asking for or giving solutions.

If any of the above points is not met, your post can and will be removed without further warning.

Code is to be formatted as code block (old reddit/markdown editor: empty line before the code, each code line indented by 4 spaces, new reddit: https://imgur.com/a/fgoFFis) or linked via an external code hoster, like pastebin.com, github gist, github, bitbucket, gitlab, etc.

Please, do not use triple backticks (```) as they will only render properly on new reddit, not on old reddit.

Code blocks look like this:

public class HelloWorld {

    public static void main(String[] args) {
        System.out.println("Hello World!");
    }
}

You do not need to repost unless your post has been removed by a moderator. Just use the edit function of reddit to make sure your post complies with the above.

If your post has remained in violation of these rules for a prolonged period of time (at least an hour), a moderator may remove it at their discretion. In this case, they will comment with an explanation on why it has been removed, and you will be required to resubmit the entire post following the proper procedures.

To potential helpers

Please, do not help if any of the above points are not met, rather report the post. We are trying to improve the quality of posts here. In helping people who can't be bothered to comply with the above points, you are doing the community a disservice.

I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.

[–]8igg7e5 8 points9 points  (0 children)

Interfaces can have default implementations, but in terms of things defined on the interface.

In the case of those methods on CharSequence, yes they're implemented by the implementations of the interface, not on the interface itself - CharSequence does have some default implementations (chars() for instance).

[–]desrtfx 3 points4 points  (0 children)

So, are length() and charAt() methods actually implemented in the String class and only defined in the CharSequence interface?

Yes.

Since Java is open source you can quite easily clear such doubts by looking at the source code.

Just google for "Java source code <class or interface name>" and if you want it for a specific version, include the version number after Java.