corejava | Experiment with performance , concurrency , database and some useless things | Database library

The Consumer passed to forEach must be non-interfering. The reasoning is explained below.

Non-interference

Streams enable you to execute possibly-parallel aggregate operations over a variety of data sources, including even non-thread-safe collections such as ArrayList. This is possible only if we can prevent interference with the data source during the execution of a stream pipeline. Except for the escape-hatch operations iterator() and spliterator(), execution begins when the terminal operation is invoked, and ends when the terminal operation completes. For most data sources, preventing interference means ensuring that the data source is not modified at all during the execution of the stream pipeline. The notable exception to this are streams whose sources are concurrent collections, which are specifically designed to handle concurrent modification. Concurrent stream sources are those whose Spliterator reports the CONCURRENT characteristic.

(Source)

BTW, your stringStream.count() would have failed even if the previous stringStream.forEach() statement did not, since forEach (as any terminal operation) consumes the Stream, and a Stream cannot be consumed twice.

The correct way to achieve what you were trying to do is to filter the original List and create a new List:

The problem is probably here: class PreferencesFrame extends Frame. It should be class PreferencesFrame extends JFrame. Frame class is fromjava.awt package and JFrame class (the one with setDefaultCloseOperation method) is from javax.swing package.

Your total imports should be:

Treating binary content like Zip files as if they were strings is usually a big mistake in most languages. On the Javascript side, CryptoJS expects arbitrary bytes sequences to be supplied as CryptoJS.lib.WordArray arguments.

So, instead of

Your request body is missing so you are getting BAD REQUEST Error. in request header u have set "Content-type" as application/json. There is a tab named body next to it. click on that and provide the json input body for Topic.

hasNext() function tells: You have a token (in your case, you have a string).

When you invoke the first time hasNext() it returns true (because you have the string s linked in your scanner object).

When you use nextLine, you represent your string s in the output so the scanner object have no more other tokens (string) so at the second invoke hasNext() returns false.

Simple:

bad class file: .\Employee.class

class file contains wrong class: com.wenhu.corejava.Employee

Your setup is somehow messed up. It seems that you have a class file for Employee in your current directory.

The package name within the class file must match the file system location!

The difference between GET and POST is that with a GET request the data you wish to pass to the endpoint is done by modifying the url itself by adding parameters to it.

With a POST any data you wish to send to the endpoint must be in the body of the request.

The body of a request is arbitrary data that comes after a blank line in the header The reqiest has the request line, following by any number of header attributes, then a blank line.

The server would need to know what the format of the body of the request was and parse it as appropriate.

Of course 'modern' frameworks like jax-rs allow you to automatically convert request data to objects, so that it is much simpler.