Java | Write once , work

You add each line to the variable list_Siswa. So for instance the first element of list_Siswa will be ["Nama"," John"], and so data_Siswa[0] equals "Nama" and data_Siswa[1] equals " John". Then data_Siswa[2] throws an error, because there is no such element in the array.

The code isn't smart enough to see Nama: John and assume the following lines are grades that should be associated with John. If you want that, you'll have to do it yourself.

You can use simply intent.putExtra instead of worrying about which variant like put_____Extra to use.

When extracting the value, you can use intent.extras to get the Bundle and then you can use get() on the Bundle and cast to the appropriate type. This is easier than trying to figure out which intent.get____Extra function to use to extract it, since you will have to cast it anyway.

The below code works whether your data class is Serializeable or Parcelable. You don't need to use arrays, because ArrayLists themselves are Serializeable, but you do need to convert from MutableList to ArrayList.

For your original code:

I think fundamentally the problem is that it gets stuck going down the wrong path. It sees a field of length 2, which we know is the minutes but it believes is the hours. Once it believes the optional section is present, when we know it's not, the whole thing is destined to fail.

This is provable by changing the minimum hour length to 3.

There is a // in the pattern that is not in the example string. Besides that, you can omit the word boundaries in between a character a-f0-9 and a - because it is implicit.

Note to escape the dot to match it literally, and you can add the word boundaries at the start and at the end to prevent partial matches.

You could update the pattern to

Use the date-time API.
(The code should be self-explanatory.)

TCP/IP connections are designed to be long-lived streaming connections (built on top of the out-of-order, no-guarantee, packet-based IP protocol).

That means that is.read(bytes) does exactly what the spec says it will: It will wait until at least 1 byte is available, OR the 'end of stream' signal comes in. As long as neither occurs (no bytes arrive, but the stream isn't closed), it will dutifully block. Forever if it has to.

The solution is to either [A] pre-send the size of the file, and then adjust the loop to just exit once you've received that amount of bytes, or [B] to close the stream.

To close the stream, close the socket. It kinda sounds like you don't wanna do that (that you are multiplexing multiple things over the stream, i.e. that after transfering a file, you may then send other commands).

So, option A, that sounds better. However, option A has as a prerequisite that you know how many bytes are going to come out of inputStream. If it's a file, that's easy, just ask for its size. If it's streamed data, that would require that, on the 'upload code side', you first stream the whole thing into a file and only then stream it over the network which is unwieldy and potentially inefficient.

If you DO know the size, it would look something like (and I'm going to use newer APIs here, you're using some obsolete, 20 year old outdated stuff):

It is because you are starting another server by ApplicationContext.run(EmbeddedServer.class).

You don't need it. It is enough to inject HttpClient into your class by constructor: