Variable Name: lowercase first letter of recommendations to meet the "small hump mode." For example: className age studentName
Data types of research
First, the basic data types (eight kinds of class 4)
1, integer
-byte-byte integer
-short short integer
-int integer (default)
-long long integer
2, float
-float single precision
-double double (default)
3, character
-char character
4, Boolean type
-boolean Boolean
二、引用数据类型：数组、类、接口、、、、、、
We define the development of the direct use of general integer variable int, float variable usually directly double.
long range particularly large
Special Note: With the change to write an integer constant is the default type int
long lg1 = 32223325522332225232; // Error
Although 32223325522332225232 does not exceed the long range but he himself beyond the scope of int, so the error
Important: If you want to just write a default integer type long, need to add L \ l in the back, this time can be large integers (recommended L, like lowercase l 1)
float also have to pay attention
float rate = 0.8 // given
Note: We just write a decimal constant is the default type double
If you want to want to just write a decimal is the default type float, followed by the required F \ f
(Not the same as long and long range can not exceed int, float not to be added)
Class can not be defined with a range of two variables
double score = 99.5；
double score = 100.1 (this mistake, this is the definition again)
score = 100.1 (this is no problem with this is to re-copy)
Range variable, the variable will be limited parentheses, brackets beyond will fail! ! !
When you can not define a variable to the initial value, but when used must have an initial value.
