Java Programmer's Way of practicing understanding 1

1, Java is a programming language, is also a platform (platform is to provide runtime environment software).

2. The JVM connects and executes the class file, and the JVM cannot directly interpret the Java source file, it needs to turn the source file into a byte-code class file.

3, the connection between the Java language and the platform is a unified class file format definition.

4. The Java bytecode is first interpreted by the JVM and then JIT-compiled immediately. The JVM bytecode is not a real machine code, it is an intermediate language in the process of compiling. Javac is just a tool for generating class files, and the real compiler in the Java system is JIT (JIT run-time compilation). So it can be said that Java is interpreted and compiled language.

5, Switch, case statement, the constant after the case statement can only be byte,char,short,int corresponding wrapper class (Byte,character,short,integer). Java7 adds a new string.

6. The numeric constant is represented by the binary text: int x=0b11001100 (11001100). Using in-place mode is more convenient. Numbers in Java can be separated by underscores.

7. Final re-throw exception in Java to ensure scope:

try{

...........

}catch (Final Exception e) {

............

}

8. Diamond syntax in Java

Hashmap<string,hash<string,object>> test=new hashmap<> ();

9. Variable parameters in Java

Java Programmer's Way of practicing understanding 1