Recently, I have learned it, I have benefited a lot, so I wrote my own feelings here for everyone to learn in the future. We have to clarify that Java is a compilation language. We compile Java's source program into one by section code file, not compiled into a machine language. When we run this byte code file under different operating systems, different operating systems
Java's virtual machine interprets this bytecode file. This is why Java is the cause of cross-platform language.
Let me explain the Java's operating environment. In the figure we see the bottom layer of "Java Hotspot Runtime" is the core layer of Java, this part is written in C and assembly language, why is Java cross?
This is because this part can be derived from different platforms. Remove this layer is written in C and compiled, the remaining layers (such as JRE, JDK part) are written in Java. We also saw a layer of JRE, this is a public runner of Java, with this thing, our Java program can run. Up to we see JDK, this Java development package
, Including compilation tools, development tools, Debug tools. Those rounded rectangles we have seen are, for example, "Text", "Util", which is the basic library of Java.
Then say the Java basic data type data type length Boolean 1CHAR 16BYTE 8 (-127 ___ 128) SHORT 16 (-32767 ___ 32768) INT 32 long 64float 32double 32 All digital types in Java are symbolic, no unint, unlong this No symbolic digital type. The data type in Java is a unified data type under any operational platform, for example, all INT types in Java, whether he is constant in any operating system, and the type encoding in Java. Unicode encoding, and the length is 16, this
This means that if I use Java's chat tool and a chat with a BIG code operating system, mutual chat language does not need our own conversion, Java can convert itself.
Ok, I will write here today, wait for the next time to meet you again.
