Learn Hardcore Malay: Saya janji tidak akan ponteng latihan renang lagi. - I promise I will not skip swim practice again.

So a very literal gloss would be:
Saya (I) janji (promise) tidak akan (will not) ponteng (skip) latihan renang (swimming practice) lagi (again).

Is janji a verb or a noun here? Is Saya janji correct, or should it be Saya berjanji?

In this sentence, janji works like a verb: Saya janji = “I promise”.

Both are grammatically correct:

Saya janji tidak akan ponteng… – natural, everyday speech, a bit more casual.
Saya berjanji tidak akan ponteng… – a bit more formal / careful, sounds like standard written Malay.

So:

Use Saya janji… in casual conversation.
Use Saya berjanji… in speeches, writing, or when you want to sound more formal.

What is the difference between janji and berjanji?

Functionally they often mean the same (“to promise”), but there are nuances:

janji
- Can be a noun:
  - janji saya – my promise
  - menepati janji – to keep a promise
- Can also be used as a verb, especially in spoken Malay:
  - Saya janji esok saya datang. – I promise I’ll come tomorrow.
berjanji
- Clearly a verb:
  - Saya berjanji akan belajar bersungguh-sungguh. – I promise I will study hard.
- Feels more standard / formal, and is preferred in writing or careful speech.

In the given sentence, both Saya janji and Saya berjanji are acceptable; the meaning is the same.

Why do we need both tidak and akan? Could we just say tidak ponteng or takkan ponteng?

tidak akan together means “will not” (future + negation):
- tidak – not
- akan – will

So:

tidak akan ponteng = will not skip
tidak ponteng = do not skip / am not skipping (no clear future meaning)

You can also see:

takkan ponteng – contraction of tidak akan ponteng, very common in speech and informal writing.

So possible versions:

Saya janji tidak akan ponteng latihan renang lagi. – neutral, correct.
Saya janji takkan ponteng latihan renang lagi. – informal, very natural.
Saya janji tidak ponteng latihan renang lagi. – grammatically possible, but weaker as a future promise; sounds more like a general statement “I don’t skip…”.

Why is it tidak and not bukan in this sentence?

Malay uses two common “not” words:

tidak – used with verbs and adjectives
bukan – used with nouns, pronouns, and for correcting identity/classification

In the sentence:

ponteng is a verb (“to skip”)
So you must use tidak: tidak ponteng, tidak akan ponteng.

Examples:

Ini bukan buku saya. – This is not my book. (bukan
- noun)
Saya tidak penat. – I am not tired. (tidak
- adjective)
Saya tidak akan ponteng. – I will not skip. (tidak
- verb)

So Saya janji tidak akan ponteng… is correct; bukan akan ponteng would be wrong here.

Can we change the order to Saya janji akan tidak ponteng latihan renang lagi?

That word order is technically possible but sounds unnatural and almost never said.

In Malay, the usual and most natural pattern is:

tidak akan + verb
- tidak akan ponteng

If you say akan tidak ponteng, it sounds awkward and over‑influenced by English (“will not skip”). Native speakers strongly prefer:

Saya janji tidak akan ponteng latihan renang lagi.
or
Saya janji takkan ponteng latihan renang lagi.

What exactly does ponteng mean? Is it just for school?

Ponteng means to deliberately skip or play truant, usually from something you are supposed to attend, like:

ponteng sekolah – skip school
ponteng kelas – skip class
ponteng kerja – skip work / be absent from work on purpose
ponteng latihan renang – skip swim practice

Notes:

It implies you should be there, but you choose not to go.
It is common in Malaysian and Singaporean Malay; Indonesian might use other verbs (e.g. bolos, mangkir).

Does ponteng always need an object like latihan renang, or can it stand alone?

It can do both, but the object is usually understood from context.

With object:

Saya ponteng sekolah hari ini. – I skipped school today.
Dia ponteng latihan renang. – He/She skipped swim practice.

Without object (context already clear):

Jangan ponteng lagi! – Don’t skip again! (listener knows what activity)
Kenapa kau ponteng semalam? – Why did you skip yesterday?

In your sentence, latihan renang makes the meaning explicit: it’s specifically swim practice you’re promising not to skip.

What does lagi mean here, and why is it at the end of the sentence?

Lagi has several common meanings, depending on context and other words around it:

again / once more
still (when used with masih)
more (as in “additional”)

In tidak akan ponteng latihan renang lagi, it means “again / anymore”. So:

tidak akan … lagi – will not … again / will no longer …

Placing lagi at the end is the normal pattern for this meaning:

Saya takkan buat macam itu lagi. – I won’t do that again.
Dia tidak merokok lagi. – He/She doesn’t smoke anymore.

If you moved lagi earlier (lagi tidak akan ponteng), it would sound odd or change the meaning, so sentence‑final lagi is the natural choice here.

Is there a difference between lagi meaning “again” and lagi meaning “still”?

Yes, the “still” meaning normally appears with masih:

masih lagi – still

Examples:

Saya masih lagi di pejabat. – I’m still at the office.
Dia masih lagi tidur. – He/She is still sleeping.

In your sentence there is no masih, and we have tidak akan … lagi, so lagi is read as:

again / anymore / no longer

So:

Saya janji tidak akan ponteng latihan renang lagi.
= I promise I will not skip swim practice again / I will no longer skip swim practice.

What is the nuance of latihan renang? Is it like “swim class”, “swim training”, or just “swimming”?

latihan renang literally is:

latihan – training / practice
renang – swimming

So it corresponds best to “swim training / swim practice”, especially in a more athletic or scheduled sense.

Compare:

kelas renang – swimming class / swim lessons (taught by an instructor)
berlatih renang – to practice swimming
berenang – to swim (the activity itself)

In your sentence, latihan renang suggests an organised practice session (e.g. team training, regular coaching), not just casually going for a swim.

Is this sentence formal, informal, or neutral? Could I say Aku janji… instead of Saya janji…?

The sentence is neutral, leaning slightly informal because of Saya janji instead of Saya berjanji.

Pronoun choices:

Saya – polite/neutral, used with most people, appropriate in almost any situation.
Aku – more informal / intimate, used with close friends, family, or people your age (depending on region and relationship).

So:

Saya janji tidak akan ponteng latihan renang lagi. – safe and polite with anyone.
Aku janji takkan ponteng latihan renang lagi. – natural with friends or siblings, more casual.

In writing (essays, formal letters, speeches), you’d normally choose:

Saya berjanji tidak akan ponteng latihan renang lagi.

Can we drop Saya and just say Janji tidak akan ponteng latihan renang lagi?

Yes, you can, depending on context.

Malay often drops pronouns when the subject is obvious from the situation. Janji tidak akan ponteng latihan renang lagi would be understood as:

“(I) promise I won’t skip swim practice again.”
or
“(We) promise we won’t skip swim practice again.”

This version:

Sounds a bit more casual / spoken.
Could also sound like a note or heading (e.g. written on a piece of paper as a pledge).

If you want it to be crystal clear and complete, especially in isolation, Saya janji… is safer.