Kanji meaning the same as chinese?

Kanji means Chinese character, but these Chinese characters may have different meanings in Chinese and Japanese, for example:

手紙，it's Chinese characters, in Japanese it means letter, but in Chinese, it's "toliet paper"

泥棒：Japanese: hooligan, Chinese: bud stick.

but yes, most Kanji have same meannings in Japanese and Chinese

I don't speak Chinese though...
For example,
羅大佑自彈自唱, 但我忘了歌名(Chinese)
I can guess that means
羅大佑(name?) is playing （the guitar）, and singing at the same time, but I forget the song's name.(?)
In Japanese
羅大佑は(ギターの)弾き語りをしているが、歌の名前を忘れてしまった。
Can you see the difference?
Some of the characters meaning the same, some don't.

Btw when I visited to China some years ago, since I don't speak Chinese I communicated with local people by writing Kanji,
I'd say that we could understand each other around 30-40 %.

The meaning of kanji is approximately the same as it was when kanji was imported to Japan from the 5th century to around the 9th century at the latest. Since then, the Chinese language has changed, including the meaning of some kanji. So also, some compounds have developed separately in Japanese, while some kanji that was invented in Japan actually went back into the Chinese language in the 19th and 20th century.

For example, the kanji for run now means walk in Mandarin. The Japanese compound for letter is toilet paper in Mandarin.

But a good part of pre-modern kanji remain reliable cognates between Japanese and Chinese, so tree is tree, mountain is mountain, and water is water. Knowing written Mandarin (traditional would be much better than mainland simplified) is a great advantage in learning written Japanese. However, Chinese students learning Japanese who refuse to learn the Japanese reading of kanji or realize some kanji mean different in Japanese are at a disadvantage.

I would emphasize pre-modern, because modern vocabulary shows a remarkable divergence. These is no Japanese kanji for computer. The kanji for airplane and airport are different in Japanese and Chinese.

But tofu is tofu.

Japanese use 3 character sets.
Hiragana (ひらがな), Katakana (カタカナ), and then Kanji (漢字)

Kanji means Chinese character, however, Kanji was imported long time ago (about 1,600 years ago), so that it's not same as modern Chinese character any more. But if you understand Chinese characters, you would be able to guess the meaning of Kanji. But you still need to learn Hiragana and Katakana.

My Chinese friends often understand Japanese sentence though.

Yes, Kanji is very close to Chinese, afterall, "KanjI" means "Han (Chinese) characters".

If you can read Chinese, then you can guess most Japanese sentences that contain Kanji.

Like the examples listed in the previous answers,
黒人 = kokujin = Black Person, which is the same in Chinese
私 = private, which is the same in Chinese
木 = tree, which is the same in Chinese

There are some that will be a bit off, like 姑 and 愛人, but you can easily guess that one means an elder female relative and the other "lover".

Though, pronunciation will be different.

Kanji Meaning

"Kanji" literally means "Chinese word" in Japanese Marley, saying it is not Chinese in origin is probably one of the silliest thing I've ever heard. @Alesha Knowing the meaning of a Chinese character may sometimes help, but not always. You also need to know what kind of Chinese characters you're learning from your friends. Hong Kong and Taiwan Chinese use traditional Chinese characters, while the mainland Chinese use simplified variants. Both versions can be found in written Japanese, while some are unique to the language. But for the most part many characters are quite similar in meaning and appearance. Imagine the word 三星 Anyone with some knowledge of Japanese or Chinese can see that it says "three star", even if they are read differently. In fact, this is the name of the popular Korean electronics company "Samsung". Similarly, a 菩提樹 is also mutually understood, even if read differently between the two languages. It's the name for a Bodhi tree. Imagine the phrase 一時間後, which is Japanese for "One hour later". Though the Chinese do not use 時間 as a form of measurement for time, just by looking at the whole phrase, it is still easy enough to interpret it "one hour later". The hour measurement in Chinese is 小時. The measurement for minutes is 分, which is the same in either language. Then there are certain words that are written the same, but mean totally different things. Take 大丈夫 for instance. In Japanese it can mean "everything is okay". In Chinese it can mean "man of honor". There are some easily mistaken ones such as 手紙 which means a "letter" in Japanese, but to a Chinese it reads as "hand paper", easily mistaken as 手紙巾 "toilet paper / tissue paper". In short, you can definitely make connections with Kanji, but due to the inconsistencies it's not the most reliable way to learn them. I would still suggest learning Kanji the way they are supposed to learned in Japanese (without interference from other languages). Worst case scenario, you're going to confused yourself when you come across those easily mistaken words.

My aunt says that the kanji writing in Japanese and Chinese are the same, but the pronunciation is different. For example, my aunt says that her friend who works in a Chinese shop sometimes gets Japanese customers, and when they try to talk, they can't understand each other. So sometimes, they pull out a piece of paper, and talk through writing.
But I don't think that Chinese had kana like Japanese. I'm going to learn Japanese, but I don't know anyone who speaks it. I know several people who speak Chinese, so I'm going to learn kanji from them, and the rest somewhere else.

Nope!

Because Japan did change a lot of meanings to kanji, they are called Kokkun kanji.

Like 沖 means shore in Japanese but rinse in Chinese.
森 means forest in Japanese and can mean dark/gloomy in Chinese

Also, Chinese has a lot of Chracters that don't exist in Japanese. Like the radical 讠

It's pretty ignorant to assume because you know Chinese you could know Japanese. Japanese is full of kana, you'll rarely if ever find a line of Japanese without any kana, because most sentences contain は、が, か, の, に, で,を, から, or まで.

I believe there are some difference.
For example, doesn't "公" mean "I" (or the first person) in Chinese?
But it means "public" and antonymous to "I" (the first person) in Japanese which is "私" (also means "private" in Japanese).

However all in all, I guess most of the kanji means pretty much still the same because Japanese people and Chinese people can communicate with each other at some degree by writing kanjis/Chinese characters (we often do so when verbal communication failed..:D)

BTW, tree in Japanese kanji is 木.
Is it the same in Chinese?