Java knowledge learned by 16.10.16

1.

Each byte is eight bits, so the range of values for each byte is -128~127, which can hold an English character, including letters, numbers, and punctuation. The number of Chinese characters, a byte can not be expressed in all Chinese characters, so the Chinese characters are two bytes to store. The char in Java is two bytes, so it can be used to save a Chinese character.

2.

Final is used to define constants, what is the difference between constants and variables, constants are impossible to modify, and variables can be changed in the program.

For example: Final int const=10;//Note that every letter of a constant has to be capitalized.

3.

Example: Float num=3. 14159//It's wrong to use this.

Example: Float num=3. 14159f//Add an F to the back.

Float num=3. 14159F//Add an F to the back.

Since 3. 14159 This floating-point type, the system will default to double type, in order to distinguish, can only be added in the following F or F to distinguish.

4.

Final-modified things are not allowed to be modified, and final-decorated classes are not allowed to have subclasses.

5.

Local variables cannot be decorated with modifiers. (Modifiers are: public,private,protected)

Java knowledge learned by 16.10.16